Why is it conventional to set line width > nozzle diameter?

There are several things at play that can make a wider line nice to have:
First layer adhesion
Due to some filaments having serious struggle to get the first line or layer stuck to the bed, it can be an easy fix to just increase the line width, generating a bigger Adhesive Force $F_a\propto A(l,w)$, where A is the area covered by the line, and thus simply $A=l*w$ with length l and width w of the line. So, a wider line means better initial adhesion and can lead to less failed prints in layer 1.
Plastic Goo
Plastics under heat behave in certain ways: they turn into a gooey substance that expands. This is also the reason why prints shrink a little as they cool. Now, if we press the plastic onto the bed with more force (as we force more plastic through than before to go from 0.4 mm to 0.5 mm) for the first time, we have a roughly flat area. The extra filament will make a wider line. The slicher can account for that, and does.
Now, next layer up: Where does the extra material go now? Plastic goo has one property that is very interesting: it tries to shrink its surface as much as possible. Heat a short piece with an airgun and it gets a little beady. But on the other hand, it comes hot enough from the nozzle to melt a tiny surface area of the already built layers, which is how layer bonding works in the first place. But our goopy plastic finds the layer below not exactly flat like the first layer found its lower surface, it finds a shape of ridges and valley. Taking into account that it wants to have the least surface to non-plastic (=air) and slightly cross bonds with the print, it will fill these nooks and crevices inside the print a tiny little better, as the increased force we use to push it out also increased the speed at which it expands to them: we reduce the time a tiny bit to reach there. How does it matter?

Well, heat transfer bases, roughly speaking, on a formula like this: $Q = mc\Delta T$ Q is the thermal energy of the object, m the mass of the object, c its specific heat capacity and T the temperature, ΔT the temperature change. But we don't have a homogenous object, we got pretty much a heat distribution with touching zones of different heat. The actual formula for the heat transfer inside the object is a long mess containing stuff like the gradient $\text{grad}T$, thermal conductivities, and integrals, but what matters is the result: The faster-expanding line of filament loses a little less thermal energy to its surroundings than the less forceful extruded line, which can increase the bonding between the two as the temperature on several fronts:

it enters the crevices further before reverting from goo to solid, leading to better adhesion for more surface.
it contains more thermal energy that can and will get transmitted to the layer below and has a bigger surface area, so it can increase the zone thickness that gets remelted a tiny bit, increasing the layer bonding strength a little.

This can result in a problem though: if you don't give the printed lines enough time to cool, it can lead to the material to accumulate heat more and more, leading to the whole thing to melt and turn into goop. An easy fix to this side problem is minimum layer time. But that would be only tangential to the original question, so look for example at the question here or the video the thermal picture above is taken from here.


My nozzle on my Ender3 V2 is higher when it is printing than it is when I auto home it

From my experience Auto Home procedure rearly leaves Z position at 0. By default Marlin raises it to 4 mm above the bed as far as I remember. The same might be with Z offset.
Also, could you please check "Initial Layer Height" in Cura?
Could you check the machine's "Start G-Code" for presence of G91 code (this would be bed sign) and confirm it contains line G90?
There are valuable basic tips in this discussion about printing too low, so you may want to go through these hints.
Did you already manage to solve your problem?


With a belt system, the belt engages roughly half the pulley. This, and the tension in the belt, ensures the belt always engages the pulley tightly. A belt and pulley system is thus relatively forgiving.

With a rack and pinion system, only a few teeth engage at any given time. To avoid backlash and get the same kind of "tight" engagement, both the gear and the rack need to be made with very high precision. The carriage also needs to be very well constrained, because any wobble of the rack relative to the gear introduces backlash (or binding). Moreover, you also need to keep the rack and pinion well lubricated lest they wear out prematurely.

Given that belt and pulley work well enough, I don't see why you'd need to move to rack and pinion. The main advantage of rack and pinion is that the rack isn't elastic. The maximum length of a belt system is limited by its elasticity, but given we aren't building meter-long 3D printers anyway, that advantage of rack and pinion does not apply.


For these kind of tests you could rely on the ASTM standards. They define test procedures and test specimen sizes for different types of tests. Or you can derive a specimen yourself based on these standards (e.g. for my bachelor's degree I used an alternative notch impact specimen as I was bound to the amount of available material of the turbine rotor blade the specimens were taken from). Considering the material, you could device up a contraption made from extrusion profiles or something.

Please do note that to get reasonable results, you would have to do a lot of tests as the spread in results is probably even more than in metals.

The company I work for does this, these material qualification programmes run for long times (years, as we also do fatigue and creep testing), and a lot of samples are tested to qualify for use in Aerospace applications.


Ultimaker Layer Resolution vs Nozzle Size

You need a certain minimum flow rate to achieve consistent extrusion. Flow rate is the product of print speed, extrusion width (proportional to nozzle size) and print speed. If you use a very small nozzle and very low layer height, you'd need a very high printing speed to achieve a reasonable flow rate. Therefore, it's quite possible this is not a mistake and intentional.

Keep in mind that Ultimaker uses 2.85mm filament. With a 0.3mm extrusion width, 0.02mm layer height and 60mm/s print speed, you would need a feedrate of 0.06mm/s into your extruder. The extruder might not be able to develop enough force on the filament at such a low speed (which, owing to the small nozzle size, requires a relatively large amount of force).

The ultimaker can not print 6 micron layers since the smallest increment the Z-axis can move in is 5 microns. 6 microns is not a multiple of that.


Problems with stock gear with no screw on Ender 3 pro

This is an older Ender 3 Pro, they at one point came with these press-fit gears, these are not intended to be removed which is a poor design decision. I would recommend buying a new motor than going through the hassle of removing it.


When leveling hotend always slams into bed?

I realised the simplest fix for this shortly after posting the question. In either your slicer or your printer controller (I use octoprint, so I added this there) add to the starting G-code something to lift the head so that it is above the point it is scraping across.

For example, change your starting G-code from something like:

G28 ;Home all axis
G29 ;probe bed

To

G91 ;Set to relative positioning
G0 Z10 ;move head up by 10mm

G28 ;Home all axis
G29 ;probe bed

(obviously remove G29 if you do not have a probe)

10mm should be more than enough to lift by unless you have something seriously wrong, but you can adjust the figure as needed.


Easy way to refine a 3D-model for 3D printing by removing internal geometry

About 10 minutes after writing the question, it suddenly dawned on me, that I was not using Meshmixer to its full potential, and especially not a simple property of Cura:

Cura can discard all parts of a model, that are intersecting a closed volume and thus are inside another volume - fixing intersecting shells this way. This option is called "Union Overlapping Volumes"
Meshmixer can, using the meshmix tool, add simple and somewhat complex geometries to specific places in given size and orientation.

Now, these two parts can be used to get rid or complex internal geometry by intentionally setting it up an intersecting shell. Usually intersecting shells are a no-no for good 3D design, but by having something - for example a cylinder - intersect just the internal geometry and enclosing it, these parts vanish in the slicing, if the slicer is set to fix intersecting shells by ignoring internal geometry. Cura does so with a simple setting, one that seems to be on by default in the 3.3.1 distribution.

So the odd solution to how to reduce a model's internal geometry without impacting the outer look can be this at times:

Manually add geometry, that (fully) encloses the internal geometry and turns it into an intersecting shell, allowing (some) slicer softwares to ignore this part.

To illustrate, almost the same area of the object before and after the added cylinder:

As one can see, the structure became much simpler, as the cylinder cuts away all the internal structure (the 'spokes' and 'axle' one might want to identify from the left picture, but that would be a misidentification) is gone. Much less internal geometry is retained and instead it is now filled with a cylindrical space of nice and fast(er) to print infill, here "Quarter Cubic".

While this is just a partly automated solution - demanding the manual addition of the intentional intersecting shell - I am yet to be taught about a fully automated way.


That is correct! Take your raw ABS plastic and try to bend and break it. Do it again with a few lengths. Pretty easy to break it right?

You issue is the material is not up to par with your goal. Your heavy duty lock takes too much force to turn.

Your solutions are to

Find a stronger material. These are considered stronger than PLA / ABS

PVA
PET
Polycarbonate
PETT (SHATTERS!)
POM, Acetal

Use the PLA to make a lossless cast of the key and use metal
Find a easier lock and or invest in oil for the lock.


The spindle screws on the gear are shipped not tight enough. Try taking the fan off and make sure the gear is seated properly and tighten the screws down. Here's a video that might help. https://youtu.be/zkZKzF3J3NA


OpenSCAD "not valid 2-manifold" useful information

Occasionally, a model created in OpenSCAD will have, as you suggest, overlapping segments. Often enough, this will generate the message you receive. OpenSCAD has an implied union function when it comes to independent objects, but if you wish to clear those errors, experiment with explicit union statements where you have joining objects. It may be necessary to join only one pair at a time to clear the error.


The CoreXY kinematics can be seen as an evolution of the H-bot kinematics. In Marlin, you both need to configure the printer as a CoreXY machine. Note that your steps are determined by the pulleys in the steppers and need to be the same for the steppers. With testing you will find out if you have the correct value.
There are many popular designs out there; e.g. the Hypercube and the Hypercube Evolution (I have built the latter myself).
I would not recommend building an H-bot, these have an inherent design flaw in that the load is asymmetrical causing the carriage to be stressed by a torque causing racking. To minimize this racking, you would require more expensive tight tolerance hardware like proper linear rails (usually not the kind that you find on typical auction or Asian vending sites, but actual pricy Japanese or German hardware). The CoreXY kinematics stress the carriage symmetrically. Note that the difference between an H-bot and a CoreXY printer is only the length of the belts, nowadays good quality belts can be bought for any length you need.
Note that a square or rectangular bed is a non-issue, just specify the dimensions in the configuration. The only thing you need to find out is how to wire the steppers. I connect one stepper to one driver and the other stepper to the other driver. I then did some tests and found out I had to flip one stepper motors connector to get the correct movement. I could have reversed this in firmware as well.


Ready to use objects instead of 3D-printing them

If your printer is reliable enough I would suggest printing multiple parts in one go. Since the cylinders are only 12 mm in diameter you can easily fit over a hundred of them on a standard 20 x 20 cm built plate with a couple of millimeters spacing in between.


Which digipot is this with the markings "AAJU"

The picture shows, that the marked chip is next to the letters U8 to U12. U is commonly used for Ineparable Assembies, but there are several meanings possible according to the ANSI/IEEE Std 315 (1975). So, let's assume for the moment that this is Assembly 8 to 12.
Note that the X-pot is marked to be down on the right side of each section, right under the sockets, and next to R103 to R107.
The Marking AAJU might belong, according to this reference, to two chips. Both are Voltage uP Supervisory Circuit
AAJU  MAX6339AUT    MAX6339  SOT23-6  Quad Voltage uP Supervisory Circuit
AAJU  MAX6726KASYD3 MAX6726  SOT23-8  Triple Ultra-Low-Voltage uP Supervisory Circuit

The pinout and look of the first chip is very much in line with what I see from the photo:

Sadly, neither a user manual for the board nor the pinout of it seems to be available at the time. My best guess based on these facts is, that it is the Quad Voltage supervisory chip, as the MAX6726 has 8 legs, as the -8 in the entry SOT23-8 indicates.


How do you calibrate a delta robot 3D printer?

This answer below is (partially) taken from my answer to Delta printer nozzle not moving square with a perfectly level bed (as if the bed is bent... but it isn't).

Whilst the answer below is for a Kossel, assuming that you are using Marlin, then the process should be more or less the same.

Calibration on any printer is difficult, but especially so on deltas, as there construction is more complex than a cartesian printer.

Have you manually calibrated the printer (at both the center and the edges), such that you can just about get a sheet of paper between the print bed and the hotend nozzle, at z = 0? This last check ensures that the first printed layer of extruded filament is actually touching and "presses on" to the print bed.

I seriously recommend that you watch this video #18:Calibration for a great explanation on the use of the paper. This video is for a Delta printer, a Kossel XL (although the Kossel Mini is also covered) and it clearly demonstrates the height that the zeroed print head should be at, and how to check using a sheet paper.

It is an hour long tutorial video, by Tom of BuildA3DPrinter.eu, and it shows you step-by-step how to calibrate the printer, and also how to deal with deformed beds (concave/convex). It uses:

Arduino IDE, and;
Pronterface

and performs the calibration by adjusting, in the firmware:
MANUAL_HOME_Z_POS, and;
DELTA_SMOOTH_ROD_OFFSET

Here is a run down of the video's contents:

0:00 Intro: The perfect first layer can be obtained, either with/without a probe (the printer is, arguably, better without probe) This tutorial is without the probe.
0:55 Arduino software loaded with Marlin firmware source, looking at the file configuration.h and in particular, the line #define MANUAL_HOME_Z_POS
2:30 - Ensure that the Pronterface USB port is disconnected as otherwise this will inhibit the Arduino IDE from connecting to the printer.
3:20 - Initial test - Gap at the center of the bed

Connect with Pronterface and use the following G-code commands
G28 Home the printer head
G1 Z10 Bring the head down...
G1 Z5 a bit more...
G1 Z4 a bit more...
G1 Z3 a bit more...
G1 Z2 a bit more...
G1 Z1 and if the head hits bed then this is too close
G1 Z2 raise the head again
Paper thickness is 100 microns, place under the head
G1 Z1.5 lower the head again, but no by so much as before
Slide the paper between head and bed. The paper should move freely, but with some friction felt (you should be able to hear the head lightly rubbing against the paper)

7:11 - Deduction of actual distance from print bed is 1.5 mm
7:30 Return to firmware, and finely tune MANUAL_HOME_Z_POS in the Arduino IDE, disconnecting Pronterface again and upload.
8:10 - Return to printer

Connect with Pronterface, again, and use the following G-code commands
G28 Home
G1 Z5 F5000 Move head down rapidly
G1 Z2
G1 Z1
G1 Z0 and the head comes to a rest at the correct distance from the bed
Retest with the paper

9:30 Final test

G28 Home
G1 Z0 Go from home straight down to the bottom

10:02 - Further calibration

G1 Z0.2 Raise head ever so slightly to give us some room
In Pronterface - Move the head horizontally
G1 X50 - Moves head 50 mm to the right
In this case, if there is a larger gap between the head and the bed. This means that the bed is curved, and convex. If the gap was smaller, or the head hits the bed, then the bed is concave

11:40 - Diagram of convex and concave print beds
12:10 - Endstops

G1 X-40 Moves the head to the left (of center) and the head is now further away from the bed than in the middle.

13:20 - This means that the endstops are not correctly positioned. So, before tackling the concave/convex issue, it is first necessary to adjust the endstops, for each tower.
13:37 - Tackling the tower positions individually

G1 Z10 For safety reasons, leave a margin of 1 cm.

14:08 - Calibrating the X tower (left tower). Note: The commands will depend on whether you have the Kossel or the Mini.

Printer moves in three axes:

X: parallel (to the front);
Y: perpendicular (to the front);
Z: height (not of interest at this point).

X tower is not in either of these axes exactly
G1 X-100 Moves the head to the side but 6 cm away from the X tower
G1 X-100 Y-60 Positions the head next to the tower correctly
G1 Z5 - Lower the head bit by bit
G1 Z2
G1 Z1
G1 Z0 and the head is still 1 mm too high

16:50 Endstop needs to be adjusted by 1 mm lower. There are two ways of doing this:

Lower the endstop itself - good for large changes
Adjust the screw - good for smaller adjustments. Turn it anti-clockwise, and raise the screw by 1 mm.
-G28 Home
G1 Z10 Bring head down 1 cm above bed
Move to the tower:

XL: G1 X-100 Y-60
Mini G1 X-60 Y-35

G1 Z2
G1 Z1
G1 Z0 Head hits the bed
G1 Z0.2
So the end stop needs to be raised by 0.2 mm, by re-adjusting the screw (turning it clockwise).
Now home it the head, G28
And bring it down G1 X-100 Y-60 Z0 and it should not hit the glass and the paper should slide underneath

21:00 Minor re-adjustment and fine tuning so that the paper slides without the need a too much force.
21:50 Repeat for each tower
22:15 Y Tower (right tower)
-G28 Home

G1 Z10 Bring head down 1 cm above bed
Move to the tower:

XL: G1 X100 Y-60
Mini G1 X60 Y-35

Repeat the above process - remember to test with G28 and G1 X100 Y-60 Z1 for safety, and then adjust the Z command
This is an iterative process

28:04 - Z Tower (rear tower)
-G28 Home

G1 Z10 Bring head down 1 cm above bed
Move to the tower:

XL: G1 X0 Y120
Mini G1 X0 Y70

Repeat above process

30:14 Re-check! each position (center, X, Y and Z towers)

G28 Home
G1 X0 Y120 Z0 Check Z tower & drop head (head should not touch the bed)
G1 Z10 Raise head (see below)
G1 X-100 Y-60 Move to X tower
G1 Z0 Drop head (head should not touch the bed)
G1 Z10 Raise head (see below)
G1 X100 Y-60  Move to Y tower
G1 Z0 Drop head (head should not touch the bed)
Calibration of the endstops is now complete

31:30 Why the Z10?

G1 Z10
G1 X0 Y0
The first calibration was the center point, but now the endstops have changed and as the bed is either convex or concave, we therefore raised the head by 1 cm, using the Z10, to avoid hitting the bed in the center. Now test it
G1 Z2 Lower head slightly
G1 Z1
G1 Z0 If the bed is concave then the head is still too high! Conversely, if the bed is convex the the head will hit the bed.

32:40 Adjusting the DELTA_SMOOTH_ROD_OFFSET in configuration.h - alter the physical parameter of the printer:

Convex: Increasing DELTA_SMOOTH_ROD_OFFSET lowers the hotend in the center
Concave: Decreasing DELTA_SMOOTH_ROD_OFFSET raises the hotend in the center
Adjust the setting in the Arduino IDE and recompile and upload (ensure that Pronterface is disconnected)

35:07 Testing the new DELTA_SMOOTH_ROD_OFFSET setting - again in Pronterface:

G28 - As the firmware has changed, we must re-home.
G1 X0 Y0 Z0
You will notice the the center point has not changed! It is the same. However if you go to the tower positions you will see that the (previously) perfect gap has changed. This is because by changing the DELTA_SMOOTH_ROD_OFFSET the center stays in the same place but the edges change instead. So, for the convex bed, we have virtually bent the surface, without moving the center point down, and moved the rim up (or, for a concave bed, down - depending upon the direction of the adjustment), thereby flattening the bed.

37:10 Demonstration of adjustment
37:51 Adjusting the height

Return to the firmware and change, again, the #define MANUAL_HOME_Z_POS line that we changed at the beginning, adjusting it by the amount that the head is from the center point.
Disconnect Pronterface and upload the new adjusted firmware.
Then reconnect Pronterface, and Home (G28) and drop to zero (G1 Z0).
The head may still a little too high.
Then move to the tower, and the head may be too close to the bed, without any gap. This means that the bed is still convex and further adjustment is required of the DELTA_SMOOTH_ROD_OFFSET and then, obviously, the MANUAL_HOME_Z_POS.
Again, this is a bit of an iterative process. Don't forget to home after any firmware updates.
Finally once the bed is flat (i.e. it has been virtually flattened in the software) and the gap between the head and the bed is the same at the center and the towers, then adjust MANUAL_HOME_Z_POS (an adjustment of 0.05 or less may be required) to get the paper test just perfect.

44:35 Check each tower (screw adjustment, of the endstops, may be required). As the bed has been flattened, mechanical sub 0.1 mm adjustments may be required. Note that the firmware does not need to be re-uploaded, when making mechanical changes - although the head will always need to be re-homed (G28) after each change.
The head should now be at the correct height.
47:14 - Extruder Calibration


MK8 extruder showing 500+ °C on temperature sensor?

A brand new thermistor shows about 95-105k ohm (depends on the multimeter quality), so it looks like that one is out of the range.
To be sure that it is a thermistor, you could connect a 100k potentiometer, play with it and see readings on the lcd. If the readings are OK, then mainboard is good so replace the thermistor.

A 100k thermistor curve


Issue with Z homing on Ender 3 Pro with Marlin

I've actually found what the issue was. It turns out that my Z steps were way out of whack (i.e. 4000 steps/mm instead of 400). Apparently, that's the default value in GitHub for version 2.0 of Marlin. Not sure if that's a typo or a valid value, anyhow setting it to 400 fixed it.


How to interpret various thermal-related filament properties?

This depends on application.
Definitions:
Vicat softening point. Vicat softening temperature or Vicat hardness is the determination of the softening point for materials that have no definite melting point, such as plastics. It is taken as the temperature at which the specimen is penetrated to a depth of 1 mm by a flat-ended needle with a 1 mm² circular or square cross-section. [However, it seems force on needle should be included.]
The heat deflection temperature (HDT) or heat distortion temperature (HDT, HDTUL, or DTUL) is the temperature at which a polymer or plastic sample deforms under a specified load. This property of a given plastic material is applied in many aspects of product design, engineering and manufacture of products using thermoplastic components. [Again, to be meaningful, the forces need to be specified.]
Basically, Vicat softening temperature involves ability to be cut, while heat deflection temperature involves distortion from an evenly distributed force. Thus, use the parameters based on whether sharp uneven forces or a distributed force is most important to your application. This can also be worded Vicat is for maintaining shape, HDT is for maintaining load bearing properties. In other words, Vicat is for uneven loading on the print, which can change the shape. The most extreme is a sharp load. HDT is for the print to support an evenly distributed load.  Many applications may be in between the two.  What complicates the issue is 3D prints are ususally printed with a fill rather than being printed solid.
Appendix
Standards to determine Vicat softening point include ASTM D 1525 and ISO 306, which are largely equivalent.
The heat distortion temperature is determined by the following test procedure outlined in ASTM D648. The test specimen is loaded in three-point bending in the edgewise direction. The outer fiber stress used for testing is either 0.455 MPa or 1.82 MPa, and the temperature is increased at 2 °C/min until the specimen deflects 0.25 mm. This is similar to the test procedure defined in the ISO 75 standard.
Limitations that are associated with the determination of the HDT is that the sample is not thermally isotropic and, in thick samples in particular, will contain a temperature gradient. The HDT of a particular material can also be very sensitive to stress experienced by the component which is dependent on the component’s dimensions. The selected deflection of 0.25 mm (which is 0.2 % additional strain) is selected arbitrarily and has no particular physical significance.


Why can my printer display remaining time but OctoPrint can't?

Octoprint is a generic application that has to work with a rather wide variety of printers and printer firmwares. The time estimation that is shipped with Octoprint by default is a very basic method that doesn't rely on any specific printer features. This also makes it kind of useless in some cases, and not very accurate.

The estimate that the Prusa i3 Mk3 shows is not actually done by the printer, it is embedded in the GCode generated by Slic3r PE. There are M73 commands added that tell the printer how far along the print job is.

As for why Octoprint doesn't do this by default, the major reason is likely that this method only works for specific printers and slicers, and only works well if the slicer can actually do good estimates for a particular printer. This is the case for the Prusa because it supports this feature and the slicer is maintained by them and has enough information to make good estimates. But this is not the case for all printers.

The feature is also not entirely standardized as far as I understand, e.g. Prusa uses slightly different M73 commands to give estimates for normal and silent mode.

There are plugins that can read the M73 estimates, you could try that. I never tried them myself, this plugin seems to do what you want from a quick glance.


In FreeCAD, how do you copy a sketch from one plane to another?

I’m assuming you are working in the Part Design workbench. Select the sketch and click Edit->duplicate selected object. Make sure that only the sketch is copied (depending on the version, either deselect the plane or click don’t include dependent objects). This will produce a duplicate sketch in the active body (if you want the duplicate in a different body, make sure it’s active first by double-clicking it if necessary). You can then click Part Design->reorient sketch to move it to a different plane.
By the way, FreeCAD has a very active and helpful forum at https://freecadweb.org. I highly recommend asking FreeCAD questions there.


The position matters a lot if you use the default STL file without doing anything in the slicer.  I've used 123D extensively and when I've inadvertently left a gap between the part and bed (and not snapped it to the bed in the slicer), the printer tries to print in mid air.  Use "d" to "drop" the object to the grid.  Different slicers have similar commands that will attach a face to the bed.  I use Simplify3D.


Weird temperature reading using thermistor on MKS GEN L v1.0 AUX-2 analog pins

Thermistors, commonly used as temperature sensors on 3D printers and other DIY things, work by changing their internal resistance depending on the temperature.

On the analog ports, the microcontroller can determine the voltage of the connected signal.

To actually measure the resistance - and thus temperature - of the thermistor, you need to build a voltage divider:

Most, if not all, 3D printer control boards use a resistor of 4.7 kOhms and a capacitor to build this voltage divider:

You'll need at least this 4.7 kOhm resistor to get your thermistors working on any analog pin, if the three thermistor ports on the MKS Gen L don't suffice for you needs.
You could also use other temperature sensors, especially for the case, like the DHT11 or DHT22, however I couldn't find whether they're supported by Marlin yet.


Bowden setup keeps jamming between PTFE tube and heatsink

Filament sometimes get stuck on the rim of the PTFE tubes inside the heat sink. Josef Prusa from Prusa Research has published a document on how you should chamfer the PTFE tubes for his printers:

Maybe chamfering your tubes works for you too.


Is it practical to build a separate hotend temperature controller to assemble hotends without taking up printer time?

You can get a suitable board for $20 or so, print a case for a few cents, and either repurpose an old PC power supply or buy a new one just powerful enough for the hotend (not bed) heater very cheap, so I think it's a lot less costly than a cheap printer, and cobsumes less space. But I'm not clear what you need it for.


Can commodity 3D printer extrusion hardware and filament be used for injection molding?

Injection molding requires two major components: pressure and heat. So your question can be broken down into those two halves: can your average extruder handle injection molding temperatures, and can it handle injection molding pressures?
Let's start with pressure.
Per this page on the University of Minnesota's site, plastic injection molding tends to require pressures of around 2 to 8 tons per square inch. Assuming you're using a 0.4 mm nozzle, which has a cross-section of 0.126 mm², that works out to be 0.000195 (1.95E-4) square inches, which translates to about 3 lb of pressure total at the nozzle assuming you're going for the high end of 8 tons (16,000 lb). However because of the way that you're treating the molten filament in the extruder as a hydraulic fluid, you've got to deal with the fact that the "piston" on one end is actually quite a lot larger area, which means you have to multiply the force by that difference in size. The cross-section of 1.75 mm filament is approx. 9.62 mm², or 0.149 in². That's 76.4 times larger, which means you need to be pushing on the end of that filament with roundabout 230 pounds, or 105 kg, of force.
For reference, the Nema 17 that's on my extruder is spec'd at 76 oz-in of torque, geared down 4:1 through a Wade's extruder, and then acting on a hobbed gear with a 6 mm effective diameter (3 mm radius). Much to my own surprise, as I write this, that means that my little plastic extruder is actually capable of just north of 160 lb of pressure force! All these numbers would need to be recalculated for 3 mm filament, and I have no experience with 3 mm, so we're going to skip that one for now.
Now, that being said, my extruder is also capable of shredding filament if conditions aren't just right. The main two problems you'll have to overcome is 1) gripping the filament hard enough without destroying it, and 2) keeping the filament from buckling. I think if you got clever with some gears keeping multiple hobbed gears synced up, and a polished aluminum or steel feed tube, you could absolutely make your own extruder that's capable of consistently putting 300+ pounds of force on your plastic filament without it buckling or stripping. The downside is that your feed rates are going to be fairly slow, so each injection molding is likely going to take you quite a bit of time. A larger motor such as a beefy NEMA23 might help offset that by giving you much higher torque at higher speeds, so long as you can melt the filament fast enough. However we'll need to revisit these pressure numbers in a few moments, after I explain a few things about temperature.
Next, let's look at temperatures. Obviously we know that we can melt the filament itself as it's moving through the extruder. Using a Volcano nozzle or something, you can even guarantee molten filament at a fairly high extrusion rate. However most printers are designed such that the filament cools to solid (60-80 °C normally) almost immediately. Injection molding designs require that the entire mass of plastic be kept molten. Fortunately, ABS and PLA melting temps are easily reached by literally any toaster oven, so stick your setup in there and you're golden, right?
But wait, there's more!
One of the problems you'll run into immediately is that extruders are carefully designed so that the plastic is molten for as little time as possible, because molten plastic against a metal tube introduces a bunch of friction, hence the need for super high pressures during injection molding. If the plastic melts too soon, then you'll clog up your heatsink (the "cold" side of the extruder), and won't be able to extrude at all. This is a fairly common source of jams in 3D printing, where you're extruding too slowly and there's not enough cooling on the heatsink. Fortunately, E3D sells a water-cooled Titan extruder that would keep the heatsink cool. However the rest of your gearing assembly, and the motor, will also need active cooling, as heat damages the permanent magnets in the rotors, and the printed geared assembly obviously will melt if put inside an oven. Your best bet might be a water-cooled Bowden setup, assuming you can find tube fittings that can withstand several hundred pounds of force. You might look into using solid tubes like brake line rather than your normal PTFE shenanigans.
TL;DR:
Get you a water-cooled extruder, make a super-strong Bowden setup, and gear down a huge motor with a bunch of synchronized hobbed gears, and you might actually pull it off! There's plenty of Thingiverse extruder files you can use as a starting point.
As far as commercially available extruders go, however, I don't think you're going to find anything that's immediately available that can handle what you need it to without some level of modification depending on your selected injection pressures.


I need assistance replacing the PTFE tube in the nozzle on our Flashforge dreamer

I got the same issue before. When you tried to push out the material from the tube, one end of the tube was being pressed. The tube was so soft that the diameter at that end was slightly increased. Hence it was difficult to put the tube back. When you tried to tighten the screw, more force applied and the tube end was pinched more. I got some spare tubes from the supplier. I simply replaced the tube. The PTFE tube could be pulled off from the nozzle.


If you want to print flat, you could easily print all parts at 90 %: the bounding box dimensions now are 81.16 x 88 mm - and as a result, you can print some other parts flat next to it but not more than one tile at the same time. Remember to print all cities and roads at 90 % too.


How to use a 3.8V stepper with Marlin / RAMPS?

The 3.8 V rating does not mean what you think it does. "Rated voltage" has a very specific technical meaning. For a 3D stepper motor to work properly, the rated voltage of the stepper motors actually needs to be significantly lower than the supply voltage of the stepper drivers.

These steppers are perfectly compatible with a standard 12V RAMPS setup with A4988 system. You do not need to and should not mess around with buck converters. All you need to do is adjust the potentiometer on your stepper drivers to limit the current to at most 0.8 A.

The rated voltage in some sense refers to the average voltage the stepper motor should see, but to actually run them at reasonable speeds you need to supply short bursts of higher voltage. A stepper driver and motor actually form a sort of buck converter themselves, and in some sense do the conversion from 12V to the rated voltage for you.


can the intel sense "xyzprinters 3dscanner" work on amd prossessors anyway?

Here are some ways a program might indicate incompatibility:

There is something in the code that is actually incompatible -- such
as some Intel-only DSP instructions.
They are using an Intel library or source code that is licensed only for
use on Intel processors.
They added a check to their code to be sure the processor was
powerful enough to handle the load, and they forgot to consider AMD
or other processors.


Based on your description of the print failures, it appears that the problem is not specific to the model. If printing supports is causing parts of the model to "fly off," there may be a temperature problem or a speed problem or a combination of the two. If you have a new filament type, it may be necessary to perform test model prints to ensure you are using good settings for the filament. If you are using old filament, it may be necessary to print test models with no complex shapes to ensure that your filament will still function properly.

You say that "PLA got all over your build plate." This is another indication of a problem not related to the model position or model design or orientation.


I'm not sure I am reading your post correctly, but if you are doing a batch of small prints, I would recommend to space them enough so as each of them has its own mini-raft, rather than all of them sharing the same large one.

If you are using cura, you can tweak how much the raft goes past the footprint of the part.  Unless you are printing very small parts, you don't need that to be a lot.

In general, you should think to a raft as a print in and by itself: the larger it is, the more prone to warping, although the way filament is layered with gaps makes the raft bend and warp a lot less than a regular print of the same size.


Why does my part-cooling fan cause stringing?

Prior to a move the print cooling fan causes the filament to cool on the outside while the nozzle is still hot, when it then moves it causes a strings to form that will be cooled instantly. This means that the cooling you have is too much and should be reduced.

This printer has a single fan to cool the cold-end and the print through a slot with the same fan. As this fan can be scheduled, it would be recommended to create a dual fan on the carriage where you have a dedicated fan cooling the cold end at a fixed voltage, while the print is cooled by a separate fan that can be scheduled through slicer settings.


This depends on your material, your nozzle diameter, and your layer height. In general, shorter layer thicknesses with wider path widths will give better overhangs. And note that the last bit of each of the larger arcs are nearly horizontal, and I do not expect them to work well without support material.

See the excellent answers at How can I improve the overhang angles my printer can successfully print?


The G-code to delay is G4.

G4 P60000 will wait for one minute. The P is in milliseconds. Some firmware also accept a S Parameter that has the seconds. So, if supported, G4 S60 would do the same thing.

The details for this and all other G-codes are documented
here.


Let's look at the general design.... it is a case... so a box of to halves. And we need some kind of connector...

How about splitting the connector into a separate C-shaped piece? That way the connector clip can be printed with the C to the plane, getting maximum durability out of either pice. You just need to print some short overhangs, the clip going around the central box, possibly in dedicated notches. Also, this is easily removable from the outside with a screwdriver. And easily replaceable. Also, both sides could be identical, if designed in the right way.

Or we use a slot in the lower body, and a Y shaped slot in the top, and make the connectors have a flat hook that matches into the lower body (push in from below) then the split top pushes through the top and latches in... This isn't removable from outside easily.

Third alternative: bolts. If the item inside the box - a PCB? - is going to be bolted to the lower case anyway, why not add extra long screws and have the top case be bolted to the lower case with the same screw that holds the PCB in place? Or, just use a pair of additional bolts and nuts on the corners.

Edit: Recently, Angus aka MakersMuse uploaded a video discussing snap-fit connections and how to make them 3D printable with the example of a backpack buckle.


Unable to export all objects to a STL in AutoCAD

Based on your error messages, it's likely you have created a non-manifold 3D object. As a simple example, let's start with a cube as suggested in your question. To keep things simple, you want to add a cylinder to the cube.

In other programs, one would create a sketch on the surface of that cube and extrude the circle into a cylinder. Because the circle is constructed on the surface, it become an integrated part of the model.

If you had created the cylinder independently, which can be done in AutoCAD and placed it on the surface of the cube, the resulting model would appear to be the same as the one created above.

The placement method may have resulted in the end of the cylinder "penetrating" the surface of the cube. Such a model may generate the face-face error you've received.

The quantity reference you've provided in your question indicates that the problem is contained in more than one intersection.

If you have patience, you can return to the original model and attempt to locate piercings or penetrations and adjust the locations to be joined properly. Selecting a wireframe view may assist you in those efforts.

Another option would be to import your .STL file into a program such as Meshmixer to attempt an automatic repair. Under Analysis/Inspector, errors will appear with flags which can be clicked to perform a repair.

Severe errors in construction, such as the one you describe, are more likely to destroy the model when using this method, however.


Shell doesn't cover the entire inner wall at some areas

You should increase the top layer thickness according to Ultimaker Cura support:

Top/bottom thickness
With the top/bottom thickness you can set the thickness of the solidly printed top and bottom layers of the print. A higher value ensures all gaps on the top and bottom layers are closed completely. However, this can also increase the print time and amount of filament used.
It is advised to always use a multiple of the layer height for the thickness of the top and bottom. This means, for example, that with a layer height of 0.15 mm, it’s better to set the top/bottom thickness to 0.6 mm rather than 0.7 mm.


Monoprice Select Mini v2 clogged Boden tube connection

If you are heating your hotend to 60/80, that is WAY too low. PLA should be at 180+ hotend, and if you are using a heated bed, 60-80.

I would try increasing the heat of your hotend, starting at 180 and increasing if it looks like it is underextruding or if you get more clogs.


Reading your question it's not clear to me if you are referring to filament retraction (which is a configurable setting) or surface recesses which seems what you are referring to when writing:

  the nature of the print surface, with lots of retracts

If it is the latter, then the answer is "no".  The amount of complexity of the surface of the model does not correlate directly to the possibility of the printer head clogging.

If it is the former, then the answer is "possibly".  It is in fact not so much the amount of retracts that affects the likelihood of a clog but rather their speed and lenght.  If you retract too quickly and too much filament, you risk to have molten plastic being "sucked" into the cold end, solidify, and act as a glue, blocking the filament in place.

This is especially true for all-metal print heads like titan aero, as plastic sticks a lot better to metal than to PTFE.

However, with a properly calibrated retraction, you shouldn't experience problems regardless of how many times / how often you retract the filament.

In general, it is a common misconception that retraction should work as a plunger, actively sucking in plastic that would otherwise ooze out of the nozzle.  However all you need is to just release the pressure within the melting chamber, and in a direct drive (i.e.: non-bowden) extruder, this requires a very minimal retraction.

Finally: what material are you printing in?  The picture shows a lot of oozing for being PLA. If you are using a flexible material like nylon or ninjaflex, you should probably just let retraction alone: the hysteresis in such materials is very high, and retraction often does not work predictably.  If it is PLA, I would try to increase the movement and retraction speed, and probably lower the temperature 10 or 15 degrees.  As for the retraction lenght, I don't own a titan, but I would expect the correct amount to be somewhere between 0.5mm and 2mm.


Z axis at print is lower than when I home

I found the issue. When the hotend and bed are at temps for PLA everything works fine but at temps for ABS the Z offset would get all messed up. After a bunch of testing I was able to track it down to a single gcode statment G1 Z15.0 F6000
At the higher temps my Z stepper skips steps at that feed rate.

The "Custom FDM printer" machine settings I used for my printer in Cura had that statement in it and so did the cat gcode that was on the card from the factory. I changed the feed rate to 200 and was able to print in ABS.

I was surprised Marlin didn't have a 'limit the feedrate for Z to this number' setting.


How to optimally make a 3D model of an object using photos?

Usually, the largest variability in 3D imaging is lighting, closely followed by the color scheme. You'll probably want to heed some of the following points:

No colors in the background/stand, keep to shades (unless otherwise specified for scanner)
No gradients. This applies to poor lighting causing a "gradient" light effect
Set the backdrop beyond the range of the scanner if possible (like with Skanect w/ Microsoft Kinect)
Ideally set the backdrop and especially the stand in contrast with the color of the object.

You're right, a typical 3D scanner will have a difficult time with darker colors due to physics. However, there are no rules that say you can't change the color of the object.

In this application, I would suggest just going ahead and spray painting the object and scanning it. Scanning the insole is going to require super tight tolerances in scanning as I'm assuming the insole is naturally worn due to use.

Completely alternatively from 3D scanning, you could try using a 3D touch probe like on a CMM (Coordinate Measuring Machine). It will take longer, but a touch probe doesn't care what color the object is.

Update

The touch probe comment seems to be a hit, so I'll elaborate. My experience with touch probes comes only from manufacturing technology and can be found and in a variety of different machine tools:

Mills
Lathes
CMMs
Vision Systems
"Romer" Arms (aka portable CMM)

You could probably get away with searching for a local machine shop (or job shop) and asking if they have a machine for reverse engineering. The quickest and easiest machine for reverse engineering (in my experience) is a portable CMM, I recommend Googling it.

Alternatively, I've heard of people adding touch probes to their 3D Printers, but I haven't seen it before. In theory, a basic touch probe can easily be achieved by using a momentary switch. If you're good with programming and maybe a bit of Arduino, you could do the following:

Add momentary (normally off) switch to Arduino
Find a way of attaching the switch (below nozzles)
Connect to your 3d printer in your preferred method and preferred programming language. I've used the provided libraries in Python that come with installing MakerWare in order to connect to my MakerBot.
Write your routine to sequentially move the new probe in a grid pattern and then incrementally move the Z up until you get a signal from your Arduino that the momentary has been switched on.
For each trigger, append a simple text file with a new line containing the coordinates.
once complete, you should have a "point cloud" of your insole which, if formatted correctly, will be able to import into CAD software

There are a few file types off the top of my head that can be used including:

.pts
.XYZ
.CSV


Which 3D printer controller should I use?

Controller boards
Please note (this is not to bash) that RAMPS shields are not the top of the line printer controller boards, investing in a more modern printer board platform (preferably not a clone of a known board), e.g. a 32-bit board might be a better solution.
Any board with at least four stepper drivers should be sufficient (you can use the two Z steppers in parallel or in series), some boards even offer two Z stepper output connectors controlled by a single stepper, e.g.:

No worries if the board doesn't have two Z stepper connectors, you can buy dual stepper breakout boards, e.g. a parallel solution:

Alternatively, an extra stepper driver can drive the extra Z stepper; this requires a board with at least 5 stepper drivers then, the Z2 stepper would then be connected to the E1 extruder driver. The firmware needs to be aware of using 2 stepper drivers, so in Marlin (depending on the version) set Z_DUAL_STEPPER_DRIVERS or assign a value to NUM_Z_STEPPER_DRIVERS .
Anet heatbed
The Anet heatbed is notoriously known for fire accidents/burning caused by the underrated connectors (the connector itself is not rated for 10 A!), also the connector should require proper strain relief. The best solution is to solder the heat bed wires directly to the backside of the connector (which is what I did on my old Anet A8 printer, I used multiple pins soldered together, both the outer 2 pins on either side), an example from the web (downside is that they only used a single pin) shows this principle (with solution for cable/soldering stress relief using a tie-wrap):

A final notice for connecting heatbeds is to use proper cables; silicone cables of proper gauge (silicone wires are very flexible, e.g. AWG 14) should be used. Also, never solder the ends and put them under screw connectors on the printer board, instead, use ferrules or proper sized fork terminal connectors.
MOSFET Band Aid
In case the MOSFETs on your boards are underrated, you can use external MOSFET boards to relieve the shield/printer board from the high currents. Note that the bed requires the most current (about 10 A), for the hotend this will not be required, the current draw is much lower, the onboard MOSFETs are rated for those loads.


Tips for not burning out my Arduino Mega or catching something on fire when wiring a Prusa i3?

Polarity matters, sometimes. Be especially mindful of the wires from your power supply to the board, as getting those the wrong way around will definitely cause damage. Heated beds and extruders are not polarity sensitive, and can go in either way. Fans are polarized, but will probably survive if you get them backwards - they just won't run. Stepper motors don't care about polarity, flipping the connector around just makes them run backwards.
Take special care with endstops. The endstop connectors have 3 pins (VCC, 5V and signal), endstops with 2 pins are usually connect to GND and signal. Putting a 2-pin endstop across 5V and GND will destroy the 5V regulator.
A common cause of damage is wires not being clamped in their respective terminals properly. The offending wire will arc, melting and destroying the connector. Tighten down screw terminals properly, use proper crimps if you have them. Soldering the ends of wires going into screw terminals is not encouraged, but if you do solder the ends then make sure to check after a while and tighten the screws again.
Put the stepper drivers in the right way around.
For things like the heated bed and wires going to your power supply, use sufficiently thick wires. Especially with the heated bed, a lot of current flows through the wires and flimsy wires will heat up and melt.


let's go step by step - and rule out the unlikely sources. Since you get at least some results, UV source and screen seem unlikely. Then you might want to make sure that the resin is ok. Let's try to put a droplet onto a sheet of paper/foil, which you tape down outside in the sun or under a UV light source - if it cures, the resin is ok.

The first real step is to check your bed leveling. Go exactly by the handbook - you might be a tad far from the bed, which leads to sticking to the film.

Then make sure your film is intact. You might need to swap resin vats to do that. in case the film is damaged, you have to swap it.


The biggest issue with RAMPS 1.4 (and 1.5) is the power connector is prone to melting/burning, this appears to be fixed on 1.6 with the use of screw terminal blocks. I've used RAMPS 1.4 with both 12v and 24v power supplies and never have had any issues with the fuses or the power connector but mine have only come from Ultimachine or RepRapDiscount.  A RAMPS 1.4 with power connectors and fuses replaced with those from a reputable dealer (Digikey, Newark, Allied) will likely be fine, you can even remove the power connector and solder the wires directly to the board if you don't need the ability to unplug them.

Whichever you go with, make sure the screws are tight and never tin the wires going into the power connectors.


Movement of the steppers is controlled by the jerk and acceleration settings. Both are controlled/set in the Marlin configuration file.

/**
 * Default Max Acceleration (change/s) change = mm/s
 * (Maximum start speed for accelerated moves)
 * Override with M201
 *                                      X, Y, Z, E0 [, E1[, E2[, E3[, E4]]]]
 */
#define DEFAULT_MAX_ACCELERATION      { 3000, 3000, 100, 10000 }

/**
 * Default Acceleration (change/s) change = mm/s
 * Override with M204
 *
 *   M204 P    Acceleration
 *   M204 R    Retract Acceleration
 *   M204 T    Travel Acceleration
 */
#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration for printing moves
#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration for retracts
#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration for travel (non printing) moves

/**
 * Default Jerk (mm/s)
 * Override with M205 X Y Z E
 *
 * "Jerk" specifies the minimum speed change that requires acceleration.
 * When changing speed and direction, if the difference is less than the
 * value set here, it may happen instantaneously.
 */
#define DEFAULT_XJERK                 10.0
#define DEFAULT_YJERK                 10.0
#define DEFAULT_ZJERK                  0.3
#define DEFAULT_EJERK                  5.0

/**


It looks like either the mechanical travel is constrained or, possibly you have the origin of the X-Y plane in the wrong place in Cura.  Usually Cura won't even slice if it thinks the object extends past the printable area, so check the display in Cura "Layer View."

If that's OK, then try using the control panel on your printer to manually drive the print head all the way in both X and Y axes.  If it doesn't then the commenters are correct thatyou have a mechanical interference somewhere.   If it does, then somewhere between Cura and your printer the "soft limit" of maximum excursion is set wrong. I'm not familiar with your printer model, but there should be a control panel command to "zero all axes," and typically the origin is the front left corner of the build plate (facing the printer, so "Stage Right" in theatre coordinates)  .


After some more testing I checked that the problem shows up only on Z tower and is not related with current. Examining the tower I found very dumb mistake. Pulley on the motor didn't have a setscrew! Don't know how could I missed that. The fact that it could somehow run is even more amazing. Thanks @tom-van-der-zanden and @darthpixel for help. It is for sure that such synchronization failure could have been caused by current shortage as well.

UPDATE:

Oh! Y tower pulley doesn't have setscrew as well! But it was running smoothly and in sync with X (which has that screw). Amazing. - UPDATE2. Not really. After closer look only Z tower misses the screw, which explains all.

UPDATE3:

After setting a srew into pulley the problem is completely gone!)


X-axis is right-to-left (Carriage motor)

Y-axis is front-to-back (Base/Bed motor)

Z-axis is up-and-down (lead screws)

There are several videos on YouTube.
This playlist seems good.


Line width changes depending on the direction the print head moves

As pointed at by @Horitsu, the Nozzle was the problem. Its outflowing hole was not perfectly round anymore, leading to a higher extrusion rate in one direction than others.

I exchanged it, and now everything works great again!


Models are printing with a scratch on the side

The vertical lines you are referring too are the result of ringing or vibration. This is commonly encountered with high print speeds, high acceleration values or if a sudden change in direction takes place.

This can be solved by printing slower, decreasing acceleration values and checking for mechanical issues. E.g. the belts may be too flexible (or contain a tension spring) or there may be a loose part somewhere.


How to calculate the proper layer height multiples?

that the NEMA17 motor would be using 400 Steps per mm in Z. configuration_adv.h tells that the microsteps on the Z-axis motor are 16.

Easy. There are 400 microsteps in a millimeter, and 16 microsteps in a full step. So, there are 400/16=25 full steps in a millimeter. So a full step is 1/25th of a millimeter, or 0.04 mm. Your layer height should be a multiple of this.

As your leadscrew has a lead of 8 mm (i.e., a full rotation will move the Z-axis by 8 mm), a full step is either 8/200=0.04 mm (for a 1.8 degree stepper) or 8/400=0.02 mm (for a 0.9 degree stepper). So, apparently, you have a 1.8 degree stepper (and this is the most common type of stepper).


The line you added:

G1 E1749.14148

asks the printer to extrude 1.7 meters of filament. The firmware likely has a feature to ignore such excessive requests as bogus. Then, subsequent extrusion amounts are also huge (1.7m+) relative  to the current extruder position (0) and also get ignored. What you meant to do was:

G92 E1749.14148

which means "set the logical extruder position for its current physical position to 1749.14148 mm" so that subsequent extruder positioning commands are interpreted relative to that initial position.


Usually when there's an overlap in two objects during a difference action, F6 render will resolve the problem. There's something more than that involved here, as reducing the height of the cube creates a non-manifold object from the difference. user R..'s answer has merit but is not going to solve the problem.
Isolating the cube from the code and exporting the result as an STL allows me to determine that the faces are generated in a manner preventing a proper difference action:

This image from meshmixer shows the faces have inverted normals. The order of the points are critical when describing a polyhedron. From the wiki page for OpenSCAD:

It is arbitrary which point you start with, but all faces must have
points ordered in the same direction . OpenSCAD prefers clockwise when
looking at each face from outside inward. The back is viewed from the
back, the bottom from the bottom, etc. Another way to remember this
ordering requirement is to use the right-hand rule. Using your
right-hand, stick your thumb up and curl your fingers as if giving the
thumbs-up sign, point your thumb into the face, and order the points
in the direction your fingers curl.

EDIT: I reversed some of the points, haphazardly and luckily picked the correct ones:
        faces = [
            [0, 1, 2], [2, 3, 0],     // bottom

            [4, 1, 0], [1, 4, 5],     // side A
            [5, 2, 1], [2, 5, 6],     // side B
            [6, 3, 2], [3, 6, 7],     // side C
            [7, 0, 3], [0, 7, 4],     // side D

            [8, 5, 4], [5,   8,  9], // slope A
            [9, 6, 5], [6,   9, 10], // slope B
            [10, 7, 6], [7,  10, 11], // slope C
            [11, 4, 7], [4,  11,  8], // slope D

            [10, 9, 8], [8, 11, 10]  // top


How to obtain high resolution prints in a shorter period of time?

You could experiment with slicing. For example, you might not need high resolution all over the object, but you can speed up some straight parts by using greater layer high there. See a part of Slic3r manual about such thing.

It is also possible to print thicker infill every Nth layer, see Infill optimization in Slic3r.

Other slicers might have those features as well.


Can I design or remix a model in SketchUp Make and legally share it via Thingiverse, MyMiniFactory or similar?

Again, I'm not a specialist in intellectual property law (or any other sort of lawyer), but I have a different interpretation.

There is a potential difference between the use of the product, and the use of the derivatives of the product. For example, GCC has a restrictive (open) license, but its OK (in some contexts) to use the compiled code in a commercial product.

Generally, you (as creator of a work) will own all of the rights to a work. The supplier of the tools you use does not usually gain any rights to the resulting work.

So long as you don't gain from your use of the tool, it is probably OK for other people to profit from the use. Sharing with non-commercial should be your safest option if you're worried - but be aware that this doesn't prevent people from taking your design to a print service indirectly.

Their license says:

  Non-commercial use means that you may not sell, rent, or lease the
  output of the Software

This implies that they are not making any claims to restrict how other non-connected persons might use your works. Its specifically talking about use as part of employment, or you making a gain.

I would also note that to me the language in the license does not look to have been drafted with a clear understanding of intent on this issue.


How to enable EMERGENCY_PARSER in Marlin firmware?

The constant EMERGENCY_PARSER is located in the advanced printer configuration file Marlin/Configuration_adv.h:

// Enable an emergency-command parser to intercept certain commands as they
// enter the serial receive buffer, so they cannot be blocked.
// Currently handles M108, M112, M410
// Does not work on boards using AT90USB (USBCON) processors!
//#define EMERGENCY_PARSER

To enable the EMERGENCY_PARSER, you need to remove the // before #define EMERGENCY_PARSER and recompile the sources.

Normally your printer will execute a command until it is ready to accept a next instruction. Without the EMERGENCY_PARSER set, the printer finishes the instruction that it is executing at the moment, if set, the execution is interrupted and immediately sent and thus not waiting for a clear space in the buffer.


The bar where the level is attached is the support cross-bar for the X-axis travel.

It's important this bar be level, but it's even more important the bar be true to the rest of the machine. We call this "leveling" the printer, but really the more accurate term is "tramming". If the bar is level, but the machine sits on an unlevel surface, things are out of sync. This may be the case here.

  I did this by unplugging the wire to one motor and modified the z-position so that the other connected side would go up. (Is this the proper way of adjusting the horizontal bar?)

No. The first image in your question shows two threaded vertical rods: one on the left that is exposed, and one on the right that is more hidden (only a small portion is visible between the two "A" labels). These rods control travel in the vertical "z" direction. Each rod has an inline coupler connecting it to the Z-stepper motors. The coupler for the right side is visible just below the square label "A". You adjust the level of the X cross-bar by turning the couplers while the printer is turned off or the motors are otherwise disengaged. This allows you to make finer adjustments for the bar, often without needing to re-home the Z axis.

You can also use this method to correct your immediate problem.

I own a Select Plus, which uses similar construction to your Select V2. When I first got the printer one of my couplers was not adequately secured to the rod. This made for all kinds of difficulty leveling the bed at first, including at one point an issue similar to what you are experiencing.

Re-leveling the X cross-bar is easiest if you are first certain the printer itself is on a level surface. If this is the case, you should be able to use the level in the images to check the cross-bar in the same way you did previously, making adjustments via couplers. But check that surface first. If the surface is not level, you need to adjust the X cross-bar to be parallel to something in the machine other than the bed. While we want the bed to match the rest of the machine, the very fact you can adjust this means it's not guaranteed at any point in time, and so you should use something more structural to compare against.

In this case, you can place the same level across the two steel Y-axis travel bars below the bed, and check where the bubble sits. Then make sure the bubble ends up in exactly the same position for the X cross-bar, regardless of whether or not that's level to the ground. The greater precision you can get here, the better things will be.

I'm gonna add some notes about leveling the beds on these specific printer models.

There are three basic types of leveling:

Manual. You do everything yourself.
Assisted. You still do most things yourself, but the machine will help by moving the head quickly to certain positions for you to check. This is what many machines refer to as "automatic", even though it really isn't.
Automatic. This is where the machine does everything, using lasers to map the bed or some other contact sensor to detect when the head approaches the bed and make it's own adjustments. Often this only uses software to compensate for the bed, and so you still want to get the bed as level as possible first without this option.

The Select V2 and Select Plus only do #2: assisted.

When I was starting out, my research indicated you should generally level your print beds "hot", because heating a print bed will expand it and potentially change the results. This makes sense to me.

However, the instructions included with my Select Plus said nothing about heating the bed, and if followed precisely meant I leveled a cold bed. Additionally, the so-called "automatic" (really: "assisted") leveling tool in the firmware also does not keep the bed heated, meaning if you want to level it hot you must do it entirely manually.

This caused me great difficulty when first starting out getting a good level, because I was trying to do it manually on a hot bed. I finally gave up on that, and started using the assisted tool on a cold bed. To my surprise and relief — and counter to what I've read elsewhere — I've had much better results when doing it cold this way. But this may be some peculiar to these printers, perhaps involving the special mat it uses on the surface of the bed.

I'm also considering this upgrade (Update: I recently installed it, but it's too soon to know if it's helping), to help improve things even further, since there is some curvature in my plate:

  https://www.amazon.com/dp/B07B251KBS/

Finally, there's an interesting seesaw effect when working on a square print bed with four adjustment knobs. I have a post about it here:

  Leveling a square 3d printer bed with four mounting posts


There are several possible causes for this. From least to worst:

The part itself is good, but the faceing cover plate is misaligned. No action needed.
The part is mounted in a way that makes it wobble, re-mounting helps.
The part is bad and needs to be replaced.

So, let's see the anatomy of a Timing Belt pulley. They exist in basically 3 general types in the McMaster Carr catalog: One flange, two flanges, no flanges. I am not affiliated with them, but they are pretty much one of the parts vendors in the industry that has almost everything, making them the convenience option. In the mantra, they are the "fast-good" option with the "everything" bonus and that the catalog of parts with 3D is integrated into fusion360. A similar supplier would be RS.

The part OP ordered is the "With One Flange" design, it is 6mm wide, 5mm axle and 16 teeth. The McMaster Carr catalog has two very close matches to OP's part: 3684N11 & 3684N12, about 6$ for a part machined from a solid piece. Why is that relevant?! well, the part OP ordered is not made from a solid piece but at least two parts: the body and one flange plate, as you can see on the product picture - the plate separation I marked with yellow here:

This is where the first error appears: if the flange isn't mounted centered (in poor quality it is rarely) then it appears to wobble but actually doesn't. But the video shows that the axis seems to be straight, while both the front and backside of the pulley wobble in the XY position. This means it is not just the flange that is mis-mounted on the part.
Now, error number 2 is misaligned mounting. In case the bore is good, you can often fix a misalignment by removing the part and mounting it again, more carefully, possibly using some thin shim metal around the axis. In some cases there is a pair of screws already to do this, if not it can help to modify the part with one or two extra alignment screws, allowing to sift the gear's center a slight bit by tensioning the additional screws.
In the case of OP's linked part, the screw that is not radial but protrudes next to the axis is designed to come over the flat of the axis and the other one is to tighten it down.
If the bore for the axis however is really skewed, and even after repeated re-mounting or shimming nothing can be done, a new part is needed. With the measurements of the part, you can order at a lot of online catalogs, the price and quality differ greatly. However, the engineering mantra strikes:
Cheap, Fast, Good. Choose two.


What is "HDPLA", and why is it so hard to find out more about it?

So, low-teck, old-style investigative work from my side.... I contacted a company selling HDPLA and they got back to me with the following reply.

  We created HDPLA as an industrial PLA with special additives. As a result, our so called HDPLA has the advantages of ABS, but prints as easy as regular PLA.  HDPLA has high impact, high strength and high heat deflection temperature (hdt). You can also print at high speed (max 140mm/s inhouse tests).  HDPLA has is own high strength, but is even more strong after annealing.  A heated bed is not necessary (50-60˚C recommended), and you can print with HDPLA with a 3D printer with open structure.

This is strikingly similar to the description of what 3Dprima calls "Prima SELECT PRO":

  PrimaSelect™ PLA PRO ist the next generation of high performance PLA for demanding industrial applications. Designed to be able to print fast >120mm/s so you can save on production time. Very high heat resistance (95°C+) after annealing. Excellent mechanical properties combined with a matte surface finish that helps concealing the printed layers for optimum appearance.

While writing this answer I also found a page that escaped my googling until now, sating an additional property of "their" HDPLA: food safety.

  With our HD PLA you have many more options. You can use this material in two ways. Choose the one you like best. You can use it as a normal PLA and get prints characterized by a very good adhesion between the layers and high precision. You can also make your prints acquire similar properties to that of ABS – better impact resistance and high temperature resistance. All you need is an oven. Yes, an oven! By annealing our HD PLA in an oven, in accordance with the manual, you will avoid all the inconveniences of printing with ABS, such as unpleasant odour or hazardous fumes. But these are not all the advantages of HD PLA. For the production of this material we have chosen raw materials that are approved for food contact in compliance with the EU directive and FDA regulations. HD PLA is also certified by RoHS.

So, it looks like HDPLA is not the shorthand of a polymer molecule, but rather a trade word indicating that the base PLA has been mixed with additives.  Furthermore, the answer I got via mail seems to indicate that "HD" refers to the high Heat Deflection temperature of the filament (the heat deflection temperature is the temperature at which a polymer or plastic sample deforms under a specified load).


3D Print D&D Miniatures delicate supports

Buckle up, this is going to be rough:
FDM printers are not the best choice for printing figurines in the 25 to 40 mm scale that is typical for wargaming and D&D games. Resolution-wise, that's the area of resin printers.
But there are ways to get some partially decent prints made:

you might want a small nozzle. 0.2 is about the smallest you can do without specialty extruders, so there is our lower limit.
You need to make sure to have a minimum layer time set, especially as the crosssections of figures are often rather slim.
Overhangs can be a pain

You might be better-served printing "meeples" than actual figurines.


From a comment can be read that the OP found the solution:

it's fixed : it's because I didn't level the bed once after flashing the firmware, once it has been done the error is no more


If you need a real shopping cart, please think about actual requirements.
Carts are sturdy devices, build on very consistent frame, because they are meant to carry heavy loads. The built must be focused on good jonts and durable wheels, otherwise forces from load or streatching would quickly damage the construction. Some parts of frame are normally under strain, and a direction of load forces is not always downwards, therefore frame has to be robust.
Cheap additive manufacturing technologies of standard printers are not suitable to produce objects of this size in one piece. If to follow this idea, one chellange would be to design pieces of the print, which could be connected or glued into a ready cart. 3d prints have tendency to snap along layers of print, therefore frame would need to be carefuly built from parts designed to be printed horizontally, rather than vertically. Construction of wheels carrying the cart with assumed load could be not possible, because load forces could mangle them very quickly.
Only the amount of material needed to print the whole thing could exceed cost of the cart. And the same would be about more expensive printing techniques, like printing of metal. The shopping cart is a good example of thing which is not worth printing (at least in 2021).
BTW: Shopping carts have some plastic parts, and printing these could be indeed possible. I suppose they are only protectors, not a part of cart construction frame.
I would advice to look to get a ready cart. Check locally for used, worn out or reconditioned shopping cart for your project.  Maybe even try to rent it somewhere. It would be much easier and quicker then trying to 3d print the cart, even if it is possible to do it within some reduced requirements.


Top layer and walls have gaps even with 120 % flow (Cura)

You are lowering temperature and increase the flow at the same time - which is contradictory (filament is less runny, but you pump more of it). Though 195 °C seems to be very safe for printing PLA at 40 mm/s. Just doublecheck that when you disable motors, and push filament with hand, it melts quickly and easily goes out. Otherwise you will deal with temperature-related issue.
Outer walls are usually printed slower, and even when underextruded, part of line may appear constant thanks to leaking filament (it has time). Next retraction will cause stop leaking, and the other wall is printed with almost no pressure. Maybe your constant issue with "inner circle" is just a consequence of such moves.
My suggestions:

Did you calibrate the extruder (steps per mm)? - if not yet, do it (it's a basic skill); to quickly check if this could help, try to continue increasing flow by 5% and observe what will happen then, because maybe this is simple underextrusion due to incorrect steps/mm?
Are you sure that extruder motor is not loosing steps? (e.g. too weak motor against the pressure)
Are you sure that filament is not slipping? (e.g. blunt driver's teeth, or too loose idler)
Could you unintentionally enable volumetric extrusion?


A masterspool is the practice of printing your own spool out of filament, which will then be used to support your filament you purchase without a spool attached. The main idea is to create a reusable spool and create less waste.

(NOTE: I'm in no way affiliated with MatterHackers.com, nor am I an endorser of their products. There is also a version which Village Plastics has created.)

On MatterHackers.com website, they state:

  Filament without a spool? Why are we making this? The short answer: because the community wants it. We had enough questions, comments and plenty of tweets asking if we had plans to pick up the Master Spool concept. Seeing the response and interest within the community made it clear to us: we needed to bring this idea to the States. With a joint effort between MatterHackers and Village Plastics, you can now purchase Master Spool refills from within the US.

They are tying to apply the Reduce, Reuse, Recycle mantra to create a cleaner environment for the rest of the world. While they are not the first to create or use a printable spool, they are pretty happy to be pressing forward with the idea of having a reusable spool and selling filament without a spool attached.

MatterHackers go on to state:

  What are the benefits of the Master Spool? Not only is there the  benefit of reducing plastic waste, using a Master Spool will also reduces shipping costs for new spools, and limits the clutter from amassing of a huge collection of used or empty spools. Rather than throwing away, trying to recycle dozens of spools, or trying to come up with a way to reuse them in some (like the Spool Tool), using the Master Spool means you can use all those filament scraps you have laying around on something useful and have one spool for all of your filament.

As far as where it started, it appears to have originated with this print on Thiniverse created by Dingoboy71. A well known 3D printer named RichRap created the reusable spool which MatterHacker promotes, though they say there are several which will work with their product (Village Plastic says pretty much the same).

If you get excited about saving the planet, then you should be excited about this. If you are a robust printer, going through tons (hopefully not literally) of filament per year, this method will save a lot of waste in the long run.

Realize there are (as of this writ) only limited suppliers of spool-less filament, though I think the trend for this type of product will increase in the future as the idea catches on. I guess time will tell.


Looks like overheating and insufficient airflow at the same time.

Try to reduce the temperature of the nozzle by 5-10 °C and increase print part cooling.


I mistakenly used 90% ethyl alchool to scrape some PLA off my bed; did I ruin it?

First of all, let's look at what kind of bed you have. According to a review, it is a "porous ceramic coated glass surface."
Your bed is fine...
Glass and almost all ceramics are virtually impervious to most liquids, be them alcohol or even most acids unless that acid is hydrofluoric acid. So on a chemical standpoint, your bed is most likely ok, just the alcohol managed to leech some of the coloration or deposit dust in the surface - which is no problem usually. The matte might even just be PLA stuck in the surface, so if this happens if you print in a different area, you know that is not damage per see it's a normal sign of use.
So from that standpoint, I see no problem.
...but there are safety issues with the bed design
Where I see a problem though is the construction of the bed itself: it runs on mains voltage and is heated directly, which can cause all kind of problems, especially breaking off the cable as there is no proper strain relief on the cable! Atop that, the review points out that the bed heats uneven, which can very quickly lead to stress and breaking of the bed.
Because of this construction, I strongly advise to refit a strain relief and use utmost care no to touch the bed during operation. Make sure not to hammer onto it and don't overheat it to prevent thermal cracking.


What is the next step after measuring the bed levels?

Now that you have leveled the bed you are ready to start printing. To enable leveling for printing, you need to add G-code G29 directly after G28 in your start G-code of your slicer.
The array values you reported are just for information or visualisation of the level of the bed. Although you have ABL you always need to provide a bed that is as level as best as you can, the ABL will take care of the final dents or skewness.


Flashforge Dreamer not able to read Cura created G-code file

For the Flashforge Creator model an alternative firmware is available; Sailfish. However, Sailfish is not available for the Flashforge Dreamer. As a matter of fact, no alternative firmware is available for the Dreamer as a consequence of the Flashforge Dreamer being closed hardware and closed source.

Not knowing the flavor af firmware (as it is closed source and could well be using a custom firmware build) using Cura to slice models for G-code files gives no guarantee for successful printing.

To be able to use Cura you would have to switch the current board from the Flashforge Dreamer and replace it with a board that accepts Marlin Firmware. Note that there is no default configuration for this pronter available so this requires a little work from you to go through the Marlin configuration file and adjust various constants to make your printer work. [edit: As pointed out below in the comments, in the process you will lose some of the maximum speed the Dreamer is capable of!]

Another option is to buy a license of e.g. Simplify3D (note that I have no affiliation with Simplfy3D!) as they claim to support this printer. There could be other software suites that support your printer.


Ender 3 V2 Z-axis base value changes for each print

After tightening the screws on the X-axis gantry and doing the bed leveling and test prints again it seems to have gotten better.
Also, while I was under the impression that the V2's heated glass bed should work well without adhesive, I applied a bit of glue stick and now my first print seems to have a perfect first layer.
I may just have been confused because I needed to turn the Z-offset way down to get it to stick in the first place, and then tweaked it upwards to get nice lines, meaning I would have to dial it back down on next test print and so forth.


Can you recommend professional 3D metal printing books?

This is a free ebook that I have perused briefly which it looks interesting, and it is free (did I say that already?)

3D Printing of metals

Manoj Gupta
ISBN 978-3-03842-591-5 (Pbk);
ISBN 978-3-03842-592-2 (PDF)

Three other books that might be of interest are:

3D Printing with Metals for Design Engineers, Explained

Ann R. Thryft
Downloadable free ebook, but some sort of sign up is required

Additive Manufacturing of Metals: The Technology, Materials, Design and Production,

Yang, L., Hsu, K., Baughman, B., Godfrey, D., Medina, F., Menon, M., Wiener, S.
ISBN 978-3-319-55128-9

Additive Manufacturing of Metals: From Fundamental Technology to Rocket Nozzles, Medical Implants, and Custom Jewelry (Springer Series in Materials Science)

Although, as the title contains a (rather obvious) mis-spelling, it does not bode well for the rest of the book.
John O. Milewski
ISBN-13: 978-3319582047
ISBN-10: 3319582046


Post-processing and filaments for weather-proof electronic enclosure

There are already some questions about the choice of filaments for outdoor use:
Which is more durable to sunlight/weather - PLA, ABS or PETG
3d printing for outdoor use: what types of filament are most weather resistant?
PLA use outdoors?
It may very well be that if you print in PETG you won't need any postprocessing.
If you still want to, you could try to paint or spray the outside with some bitumen spray for car underbody.
I think that the only part which actually needs postprocessing is the spot with exposed moving parts.
It's difficult or impossible to find a solution without having an idea of what we are talking about when you say "some moving parts exposed", but in general this is solved first of all by adapting the design so that water wont' be an issue: rain should flow away without getting inside, and spatwater should be reduced so that it will evaporate when rain stops.
If you only have an exposed pin for rotating parts which are inside, you could also pour some wax: it will seal it while allowing movement. The same bitumen spray may help.


DQ542MA Driver proper settings for NEMA 17 Stepper Motor

It is completely normal for a stepper motor to get hot. Taking this datasheet for example, specifies a 80 °C temperature rise. That is, in an room that is 25 °C ambient temperature, the motors would get up to 105 °C.

To prevent the motors from getting as hot you could further reduce the operating current, but likely the temperature they're running at is normal.


3D printer out of normal printer (HP PSC 1315)

No, Printers are not good sources
Common printers contain at best one stepper motor in the scanner, and it is usually too weak for use as an X or Y stepper, but for a very slow printer they might be useable, especially if you could source 2 or 4 of the same type.
The main motors in the printer are almost universally DC motors that get their turning signal as a voltage from the main board, which again uses positional information from an encoder strip/disk. Using both of these to make a 3D printer is usually not feasible.
However, they usually have good rails (sadly often of non-standard diameter) and might be salvaged for a decent optical sensor. See also Thomas Sanladerer's video about this.


Filament spreading apart and stringy on first layer

I would try two things you didn't mention; a bed leveling (this looks a little close) and an e-stepper calibration. The layer looks thin and under-extruded, and two common culprits are the bed height being too close ("oversquishing" the first layer which reduces flow rate and adhesion), and the e-stepper not feeding as much filament as the slicer's asking for (giving you thinner lines than the slicer expected, so they don't adhere to each other or the substrate).

I also see problems with that kapton layer. Totally understandable, the stuff is a major pain to lay down bubble-free, however it's also absolutely necessary to do so to avoid first layer issues. That's not your only problem here but it'll keep being a pain after you have filament feeding sorted out.

Lastly, I'm seeing slicer error; the floor fill is being laid down over the top of the shell layers on the right side of your image. Remember that the wealth of slicer variables in Cura regarding print speeds, flow rate, filament diameter etc ultimately boil down to a single G1 command per line: "move from here to here at this speed extruding this length of filament". So, if the slicer is forgetting where it drew the outline by the time it scripts the floor fill, it's possible it lost the plot on extrusion calculations as well. Alternately, the printer could be the one that lost the plot, either losing track of the steppers or incorrectly interpreting the G-code. Usually you just need to power-cycle the printer, close and reopen Cura and re-slice. Also, if you're printing with a USB cable, try switching to an SD card; there's less to go wrong in the communication between slicer and printer if the slicer tells the printer everything it should do up front.

I'd look into each of these, then try to print a calibration shape, like a 20mm XYZ cube, before going back to the print you had on the plate before.


The last version of Ultimaker Cura that supported 32-bit Operation Systems was Cura 2.3.1 of 2016, which of course has a lot of items not yet in it and doesn't fit the demand of offering some update at worst from 2018.
32-bit support is starting to fade from the support of projects, as 64-bit makes a lot of things much easier and faster and 32 Bit Windows likewise is pretty much a dead-end branch with Windows 7 Support being discontinued on January 14th, 2020. For example, the Slicer project says on their documentation of the May 2019 4.10 version: "We do not make 32 bit builds available."
Yet there is rescue with the Slic3r-Family!
Slic3r 1.3.0 is open source, available as 32 and 64-bit versions, and was released in November 2018, making it somewhat up to date. You need to customize a lot of settings in it, but it is after all quite a powerful slicer - for which you have to write your own Start Code, define your filament settings and machine.
Repetier Host 2.1.6 is likewise a 32-bit application. It's technically a console with slicing features and uses one of several engines to slice - including the Slic3r and Slic3r Prusa Edition engines, which run on 32-bit. In comparison to Slic3r, I find its UI for placing items a little more user-friendly. It does pull the settings from Slic3r, if you have that installed.
Slic3r Prusa Edition/PrusaSlicer is a derivate of the Slic3r project. 2.2.9 was released in December 2019. It too runs on 32 bit systems. It is, UI-wise, even more comfortable than Repetier Host and is somewhat similar to Ultimaker Cura 4.


Is 3D printing useful for making everyday objects or is it more for special hobbies?

Have people been using 3D printing to genuinely create a number of needed objects in their homes, and if so, what?

Yes, but in a very limited sense. If there is widespread demand for an item, then it will always be available from stores. This is basics economics: if there is enough demand for something, somebody will step in and provide the supply. The store-bought alternative will almost always be of better quality and relatively cheap.

3D printing can be useful to create a niche part that is needed but not readily available, such as replacement parts for appliances long out of production. This unfortunately takes a lot of time since you need to make a 3D model of the part yourself, which also requires considerable skill.

Some examples of items that I made for my home:

Custom brackets to hang blinds when the store-provided ones did not fit my window.
A special mounting bracket to more easily hang a ceiling light panel.
Replacement wheel for a vacuum cleaner.
Cover plate for a deprecated telecom socket.
Fix for a broken clothes drying rack.

3D printing can also be used to create "trinkets" such as custom vases or similar objects.

I would say 3D printing is a bit like woodworking as a hobby: it is a skill that can be used to make genuinely useful items, but going to IKEA is a perfectly viable alternative.

  Or is 3D printing better for special niche interests like art projects, home engineering projects, etc?

It is ideal for this. I do not know of anybody who has a 3D printer specifically for home use. However, there are many hobbyists that use 3D printing for another primary purpose that occasionally find their 3D printers useful around the house.


If you have a specific shape in mind and can create a sketch to represent that shape, you are halfway to your goal.

The concept is simple. Create a single line sketch that would represent the desired curve, starting from, in this example, the nose of the cone and traveling to the base. Create only one-half of the nose cone curve and maintain a "standard" axis reference, say, using the Y-axis as the rotation point.

The process is called revolve. Fusion 360 supports this action directly.

In the Sculpt workspace, choose Create Revolve.
Select the profile to revolve.
In the Revolve dialog:
    Click Axis and then select the axis to revolve around.
    Choose Full or Angle to specify whether the revolution is full or to a specific angle.
    For Direction choose One Side, Two Side or Symmetrical.
    For Symmetry, choose None or Circular.

The above text is taken directly from the link. The specific web site also includes a Flash video of the steps involved.

If thickness is required for your creation, consider to draw the sketch from the nose to the base, then use Offset or hand sketch in a parallel line that returns to the nose. Ensure the base segment is joined and that the nose segments are open and are aligned to the Y-axis.

As the sketch is revolved, the nose sections will "close" while the base creates the closure necessary to make a solid that is hollow within and open at the bottom.

Use The Google or your preferred search engine with the terms "Fusion 360 Revolve" to find many tutorials and videos with the same information presented in various ways.


How do I concave an image to create a 3D file for use in a 3D printer?

What you describe, sounds like you want to create a lithophane; a pattern etched or engraved on a thin translucent base material (in your case a bowl) that can only be seen clearly when backlit with a light source behind it. Apparently you want to use it for another purpose.

Special software and or scripts that transform the image to the base material exist. An example is e.g. this sphere which becomes a globe when lit from the inside. Recommending a tool for creating such bowl is a little out of scope as these types of questions become outdated very quickly as technology changes or tools cease to exist. With the provided information you should be able to find software that is able to provide what you want to do.


How to set the boundaries for BLTouch probing

As explained in this answer it is you that needs to calculate where the head (read sensor) is supposed to go depending on the amount of space you have left on the carriage shafts.
As can be seen from your configuration, your sensor is located on the left front (when facing the machine) at 41 mm left from the nozzle you are requesting the sensor to travel to a position that is outside the bed (35 mm), so you should at least subtract 41 mm from your X bed size.
As you have not posted a bed size, an assumed X bed size of 220 mm would mean that the maximum probing distance for X (i.e. RIGHT_PROBE_BED_POSITION) of 220 - 41 = 179 mm
In your case -41 mm would take it to the edge, so 30 mm extra would make it symmetrical:
#define LEFT_PROBE_BED_POSITION 30
#define RIGHT_PROBE_BED_POSITION (X_BED_SIZE - 41 - 30)
#define FRONT_PROBE_BED_POSITION 30
#define BACK_PROBE_BED_POSITION (Y_BED_SIZE - 5 - 30)

Furthermore, it is way more convenient to set the Z distance between the probe and the nozzle using M851 Zxx.xx (where xx.xx denotes the offset as a negative value) than setting it with Z_PROBE_OFFSET_FROM_EXTRUDER.


Issues with printing and removing filament residue

I think I know the answer to your first problem.
Check your flow rates and wall thicknesses in the slicer settings. And if messing with some of those settings doesn't fix the problem, it might have to do with your steps per mm which I posted an answer here.
The other two problems I'm not really sure about.
Just wanted to at least get one question cleared.


I'd go for the easy option of using a composite setup: Acrylic lacquers themselves are very low reactive and can serve as a foundation before the UV clear coating is applied. The acrylic lacquer itself doesn't change coloration if exposed to sunlight, but the light can still pass and discolor the lithophane.
Your Krylon clearcoat technically is an acrylic paint, but to be used from a rattlecan, other chemicals are added - a whole lot as the MSDS tells us. The list of chemicals besides the paint in that can are Acetone, n-Butyl Acetate, Propane, Butane, Xylene, Ethyl 3-Ethoxypropionate, Cyclohexane, Ethylbenzene,
Bis(pentamethyl-4-piperidyl)sebacate. Three simple chemicals I put in italics - they are very good solvents that easily react with the resin print. Propane and Butane create the pressure in the rattle can, the other four chemicals make up the actual lacquer. I have observed the mix of Acetone, Cyclohexane, and Ethylbentene (with possibly others) softening PLA, so it is totally possible that they react unfavorably with your resin print. As a result, I suggest using a brush or roller to apply acrylic paint from a can (not spraycan!)


Masking tape (and blue painter's tape) is coated with a wax-based release agent in order to prevent the tape sticking to itself on the roll. This release agent must be removed with an organic solvent in order to obtain good adhesion. Isopropyl (rubbing) alcohol is good for this. Acetone will also work, but it is a much stronger solvent (which is not necessarily a good thing).

For blue painter's tape, rub freshly applied tape with solvent until the blue dye starts coming off. Then give it a quick wipe between prints to remove any fingerprints, etc.


Specifications of Prusa Mini X-Axis Belt

To be sure you could measure the width and the tooth spacing (pitch). The most probable and used belt in 3D printers is the GT2 6 mm belt. The teeth are spaced 2 mm and the width is 6 mm.


The first screen of Marlin 2.0 is showing some horizontal lines, appearing to be broken

Something is causing your screen to get signals to display that before your board properly takes it over after 3 seconds.  It is an oddly repetitive pattern.

If it is software, you should not see it on a stable stock marlin release with minimal customizations to enable the LCD.  Usually nothing else shares pins with the LCD, but please do double check pin assignments.

Beyond software lies a realm of hardware issues:

Issue could be due to bad wiring or wires running in areas where they are picking up noise as the system boots up; LCD ribbons are not particularly noise resistant.  I say wiring but it could be anywhere along the circuit, including circuit boards.

There is also some (smaller) chance that your power supply is providing the noise at the initial boot up in which case you may be able to resolve it by adding capacitors to stabilize the DC voltage.  Not sure what check you already did of the power supply, but a DC (RMS) reading may not show anything strange on a regular multimeter even if there is a strange AC signal.