How to set Home Offsets and Manual Home definitions in Marlin correctly?

Normally you wouldn't use the MANUAL_xyz_HOME_POS at all.
Home your machine.
Use a caliper or ruler to measure the distance between the nozzle and the edges of the print bed in both the X and Y direction.
If the nozzle was off the bed in both directions, input these measurements as negative X_MIN_POS and Y_MIN_POS values.
If it was over the bed in either of those directions, you'll need to input them as positive positions.
That should result in your nozzle to be exactly on the edge of the bed after a
G28 X Y
G1 X0 Y0

movement.


How to interrupt long command with G-code?

3D Printers are pretty basic when it comes to g-code. There is no cycle start or cycle pause function on them. There is also no g-code command to interrupt the previous command. To get it to a halt you could turn it off. Or if the printer's firmware is configured to do so, you can touch one of the limit switches to get it to stop its movements.


Why do slicers have nozzle size settings?

I never thought about that!

I do know from experience that Cura uses nozzle sizes to sanity check your settings, warning you if you do something unreasonable. That is reason enough to include the feature for me. However, I did wonder what, if any, differenced this actually makes, so I tested it and here's my results:

I went through and tested it on the 3DVerkstan Face Mask. I compiled the same model in the same place in Cura, the only differences between the two being that I changed the nozzle size from 0.4 mm to 0.8 mm. I then ran the VS Code Diff Checker on the files as well as loaded the exported gcode back into Cura to compare and got some interesting results.

The estimated times and filament usages are very slightly different: 2689 seconds for 0.8 and 2698 seconds for 0.4, 6.18899 m for 0.8 and 6.18883 m for 0.4. This means something different is happening somewhere, but it's very similar to within a rounding error.
The brim is exactly the same for both. No differences whatsoever in the G-code.
When the model starts printing, everything in the gcode becomes different. This seems to be down to a few reasons: (note these photos were taken by exporting gcode then re-opening that gcode into Cura)

Differing layer start positions

Possibly a difference in line overlaps? On the 0.8 mm file, cura shows a larger gap between the brim and the part, and more overlap between the outer wall and inner walls when compared to the 0.4 mm file.

That's all the differences I can observe in this model. Every layer is different in the gocde, but it seems to be down to the two differences noted above. IMO, that's all inconsequential and you should be fine to change all the settings to how they should be for a larger nozzle and be just fine. Other than the warnings, nozzle sizes may be a holdover from a past version when they were more useful, or simply may have just seemed like a reasonable feature to put in at the time and no one really thought about it.

As far as changing nozzle size goes, I go to Preferences > Configure Cura > Printers > Machine Settings > Extruder 1 > Nozzle Size. If that option is not there, consider creating a new machine of a different type that's similar to what you have. I have an Anet-A8 but use the Prusa i3 printer type in Cura since that's most similar to what I have.


When assembling the hot end tip, make sure you screw in the extruder tip to the aluminum block first, then screw that assembly to the heat sink fins. On my Kossel, I did it the other way around, and had very poor results.

If the whole assembly is spinning, then the clamp screws are either too long and can't tighten properly, or the holes might be stripped, or they're just not tight.

And yes, any movement in the hot end can cause problems, since we're dealing with steps as small as .1 mm.


ABS prints consistently splitting in the same place

Personally, I have dealt with this problem myself! I messed around with the slicer a little bit, and I found that if you make the print layer height 0.15 or 0.10 mm, it will be better. The image you attached looks as though the printer was splitting a step and only printing that part. I can't think of a reason why it would do that. I also can't find anything online, so I would just play with the print settings or change the layer height until it comes out how you want it.


What is the life expectancy of the Kossel?

Much like your car, the number of miles, or the number of prints that you can get out of it is entirely up to how well you can maintain it.

A 3D Printer is a machine, and a machine needs general maintenance; if you see something starting to break - or get worn out - or anything abnormal, fix it.

I am sure that if you had something like a MakerBot, it would require less maintenance then a fully home built machine, but if you are building it from scratch, I am sure you don't mind.

I am still rocking a 3 year old home built MendalMax, and have both made some improvements, and had to make some repairs along the way - but it is still in damn good condition.

For a $600 investment, I can say you will get a few years out of it if you take proper care of it. By the time the end of its life comes (5+ years), I am sure there will be much better printers available for cheaper, and you will never look back :)

Tighten all your nuts and bolts
Keep it calibrated
Keep belts properly tensioned
Oil X, Y, and Z rods
Clean of any dust and scrap plastic (compressed air can?)
Clean hobbed bolt
Clean extruder
Ensure all electronic connections are secure
Check wires at points of movement for wear

!remindme 5years


Still got poor printing quality after calibrating my Anycubic Predator

A few tenths of a millimeter are pretty common for 3D printed parts; these are related to the printer hardware. These inaccuracies can be exaggerated by over- or under-extrusion; e.g. if too much filament is extruded, it increases the outer dimensions (and decreases the inner dimensions of holes).

The images show some signs of over-extrusion, maybe a little too hot also.


Setting custom x/y bed bounds for Anet A8/marlin

As you just flashed your own Marlin, you probably have the marlin.ino and its associated files in the Arduino IDE set for your Processor and board and know how to work with them to some degree. This is just the short version where to find what you need to change the bed size, if the marlin.ino is based on the marlinfw-release.
Changing "home"
In Configuration.h there should be a set of lines that reads akin to this:
// Travel limits (mm) after homing, corresponding to endstop positions.
#define X_MIN_POS 0
#define Y_MIN_POS 0
#define Z_MIN_POS 0
#define X_MAX_POS X_BED_SIZE
#define Y_MAX_POS Y_BED_SIZE
#define Z_MAX_POS 200

Usually it is faster to use Ctrl+F and then typing in X_MIN_POS and adding the hook in front of Search all Sketch Tabs and then moving through all the finds till the right one pops up. This not only brings you right to the lines you want to alter, but also covers up the bases in case the distribution you work with did put the movement limits into a different location like Configruration_adv.h.
Changing Bed Size
Alter these minimum positions and make sure that the Maximum positions (usually just after them) to fit the maximum of the bed.
If you reduced your bed size, you also might need to change X_BED_SIZE and Y_BED_SIZE, which (in the marlin.ino) is in the same Configuration.h - I found it to preceede the Travel limits:
// The size of the print bed
#define X_BED_SIZE 200
#define Y_BED_SIZE 200

Adjust these as needed to fit the new sizing.
Hint: Getting the Values for Adjusting
For finding the adjusted values, I have had good experiences using Repetier Host on Manual Control to move the nozzle (lifted 1mm to prevent any accidents) into the correct XY-position and taking this position as adjustments for the minimum positions. Finding your personal settings is a bit of a trial and error still, so take your time.
Finishing up
Now, recompile the marlin.ino (the checkmark in the top left) to check for errors and flash the new firmware it.


Z offset in Marlin is not working recently

I have the same problem. You need to check your G-code to detect where's the problem.
Try comparing the G-code file with different values of the Z offset.
In my case it looks like this:
No offset
;LAYER_COUNT:107
;LAYER:0
M106 S255
G1 F300 Z0.84
G0 F6000 X124.645 Y78.208 Z0.84
;TYPE:SKIRT
G1 F300 Z0.44
G1 F1500 E0

With offset (comments made by Cura)
;LAYER_COUNT:107
;LAYER:0
M106 S255
G1 F300 Z2.06 ;adjusted by z offset
G92 Z0.84 ;consider this the original z before offset
G0 F6000 X119.093 Y42.498 Z0.84
;TYPE:SKIRT
G1 F300 Z0.44

I hope this helps.


How does the home position work on a Prusa i3 RepRap Printer?

It works like you describe, but it does not move all axes at the same time. It first moves the X-axis, subtracting steps while the X endstop is not pressed. When the X-axis is is homed (the X-endstop is gets pressed) it repeats the procedure for the Y-axis and finally the Z-axis.


Is "CoreXE" a thing, or is there a reason it's not?

Wow, Kevin O'Connor (of Klipper) just pointed me to a real CoreXYE design by Vlad Strateniuk called REXY, with video available:

There's an open Klipper issue about supporting it and apparently Marlin was already adapted to run on it.


How to build the extruder motor holder for the Kossel Mini

Have a look at the image provided in this seller's part description. it probably says more than my words could (which would also only rely on images - your parts just looked like I saw them somewhere before).

3D printer parts right hand Bowden Extruder kit set no motor compact extruder aluminum alloy for


What I could suggest here is:

set the acceleration to 1 instead 0 so we have M201 X1 Y1
use G1 Xdest Ydest F3 - feed rate is given as an integer


In Fusion 360 how do I select an entire 3D object, not just its sides or faces?

Selecting the body in the browser will select the entire body. Clicking on the body in the viewer will only get you faces or edges.

A long click (click and hold) on the model will give you options on what to select. You can choose a face or body under "Depth" or choose a body or feature under "Parents."


Plug sdramps module and Anet A8 LCD together into RAMPS smart adapter

The Anet A8 uses a simple LCD with 5 buttons, the problem is that the buttons do not use digital pin signals, instead analog pins are used. Based on the pressed button, with corresponding resistance the firmware knows which button is pressed. The RAMPS smart adapter uses digital pins, so the Anet LCD is not compatible with the smart adapter, you may wan't to opt for a cheap Chinese 12864 LCD smart controller, they are about $8, they are compatible.

The topic Connecting (Anet A8) 2004 display to MKS GEN L shows you to hook up the Anet A8 LCD to a RAMPS board. You do not use the smart adapter, instead you use AUX2. You only have to change 2 wires (interchange them on AUX2) and you will be able to use the display. The reason you cannot use the smart adapter is that the 5 button display requires analog pins, which are not available on the smart adapter, but are available on the AUX2 header.


Why would all of the Ender 5 Pro's axis motors (X, Y and Z) stop being able to move (all at once)?

The Creality V1.1.5 board was fried. I replaced it with a BIGTREETECH SKR MINI E3 V2.0 32BIT CONTROLLER. After struggling to find a corresponding firmware for the Ender 5 pro, the axis motors worked correctly.


I want to print an image of a network in 3D — what's the best way to convert it?

Unfortunately, with only a .PNG or other file format that is traditionally two dimensional, you are missing some critical information. Unless your objective is to print something "flat with thickness," you can't create a 3D model. If your objective is to print something flat with thickness, even a program such as Inkscape with the Path to OpenSCAD extension will accomplish your goal.

I believe that Tinkercad will import images and allow you to extrude them to create the thickness aspect. Another program which supports such activity is Fusion360 (free for hobbyists) which would convert your drawing to a sketch. You'd have to add some width to the lines in order to extrude them in any program you select. It will also be necessary to trace the drawing to convert it to a vector file type. Inkscape excels in this task.

Lastly, you can arbitrarily add a third dimension to the diagram by importing it with SolveSpace. It is another free program which allows one to import a DXF file. Note that DXF is a vector file not raster, excluding your existing PNG format. It might be easier to use Inkscape to create the vector file, add width to the lines, then save it in DXF form and load it to SolveSpace. At that point, it becomes extremely challenging due to the complexity of the drawing.

Perhaps a hint or two (image, sketch, drawing) of your final objective?


After several email exchanges with the customer support, I was not able to find an answer. It was stated that it may have been my assembly and/or extruder mount, but I'm strongly against that after so many times reassembling.
Gear backlash ended up becoming permanent.
I ended up switching over to something else with a more self-sufficient design and less variables.


I spoke with a chemist tonight.   He said to start with the SDS (or MSDS) for the filament,  which is required to be available for most materials.   It should list the pigments and additives if they are not recognized as safe.  If they are safe,  non-toxic, not flammable, non-reactive, they might not be disclosed on the data sheet.

He warns that sometimes the SDS lists just an industry name for a common pigment,  and sometimes is the full chemical name.   IMO, Google may help with translation.

The chemist has a deep background in color science and pigments.


To answer your first question:

Your calculations are not wrong, they are correct for a normal layer (uncorrected) layer. These calculations should get you very near the solution. The problem is that there are default modifiers at play that modify the extrusion process which become apparent when you change them or look at the hoover hint in the advanced printer settings section. E.g. see the image below of the "Print Settings" graphical user interface; specifically look at the hoovering hint:

The hoovering hint tells you that there is a 200 % modifier at play. What! a default modifier without me knowing? Well...., if we had looked at the
Slic3r Manual (The Important First Layer) a little better, we read that:

  Fatter extrusion width. The more material touching the bed, the better
  the object will adhere to it, and this can be achieved by increasing
  the extrusion width of the first layer, either by a percentage or a
  fixed amount. Any spaces between the extrusions are adjusted
  accordingly.

  A value of approximately 200 % is usually recommended, but note that
  the value is calculated from the layer height and so the value should
  only be set if the layer height is the highest possible. For example,
  if the layer height is 0.1 mm, and the extrusion width is set to 200 %,
  then the actual extruded width will only be 0.2 mm, which is smaller
  than the nozzle. This would cause poor flow and lead to a failed
  print. It is therefore highly recommended to combine the high first
  layer height technique recommended above with this one. Setting the
  first layer height to 0.35 mm and the first extrusion width to 200 %
  would result in a nice fat extrusion 0.65 mm wide.

Tada! There we have the modifier from the screenshot; 200 % (this is expressed as a percentage over the layer height, and causes that an additional filament scale factor bigger than 1 is at play; the $x$ in your equations).

To answer the second question:

That should be rather straight forward, you know how long the path is and at which speed the head is moving (either at constant speed, decelerating or accelerating) and how much of filament you need to deposit, at the end point all filament needs to be deposited so you can calculate how fast the extrusion needs to be to accomplish that.

If you calculate back from a volume of 8.214 mm2 and solve for unknown $w$ you see that this yields $ w = 0.65\ mm $, and that is exactly what is stated as first layer width in your Slic3r settings; I quote:

  first_layer_extrusion_width = 0.65

P.S. When you look into the source code of Slic3r, if you dig deep, you find that extrusion width is bound by minimum and maximum values, it could well be that that is causing the value to differ from 0.70 mm (200 % of 0.35).


Mixing nozzle vs dual nozzle vs IDEX vs tool changer for pva and pla

I would advise against mixing nozzle - you would have many jams and clogs and you would have to use purge tower which in my opinion is not worth it. Thats scratching point 2.
Point 1. and 3. are similar to some extent. With both types you have to align the nozzles in all three axes. Crude aligning should be done by hardware and fine tuning done in software (too much difference in Z alignment could cause one nozzle hitting the printed part). Anyway, the aligning is pain and you will have to do many test prints to achieve sufficient results.
In my opinion, point 3. (also called Idex - independent dual extrusion, I believe) will give you best results, because while one nozzle is printing, the other one is parked on the side where it can ooze as along as you manage to wipe it when it is getting ready to print. You can use purge buckets. Also you have to home the extruders indepentently as well (one to right and one to left).
Point 1. will introduce a lot off oozing issues. You would have to use ooze shield, or other methods of wiping the other hotend, if you are comfortable with that.
As for connecting another axis to Ramps 1.4, the board has 5 stepper motor outputs (X, Y, Z, E0 and E1). Therefore there is no output for another X axis, since both E0 and E1 will be used. You have two options I can think of:
Creating your own stepper output and connecting it to auxiliary pins on the board (if you are using legacy stepper drivers, you need 2-3 pins - direction, step, (and motor enable)). That requires some basic knowledge of electrical devices and firmware. However, it is doable. Not easy for someone without sufficient knowledge, but not impossible either.
Or the other option is to buy an existing boar with 6 stepper motor outputs such as Bigtreetech SKR PRO. You still have to configure the firmware but it is much easier this time (it has been made/pre-made several times with tutorials).
I would suggest using Marlin firmware as it supports many configuration types and has very strong community - someone has likely solved your solution or can help you solve yours.
I would also suggest not using Ramps board with Arduino Mega2560. That board configuration is so old. 3D printers have moved on, whereas that board has stayed the same for 5 or so years. It is OK, perhaps good for tinkering, but there are far better options (such as the mentioned BTT SKR series boards).
Good luck with your design.
Note: I do not own a dual extrusion printer of any of the mentioned types. This is just my understanding of the theory and how I would do it, if I were to build a dual extrusion 3D printer.


Can 1.75 mm filament be used in a printer that takes 3 mm filament?

Typically an extruder and hot end are designed for one or the other, and cannot support the other without mechanical changes.

The extruder may not be able to grip a smaller diameter filament with enough force to assure even feeding and retraction.

The hot end, however, is much more complex. The filament has to be pushed with force into the melting zone, which means the filament has to slide along an area inside the hot end where the filament is plastic but still put pressure on the filament ahead of it.

When you put filament into a hot end, the filament softens before the melt zone, but since the walls of the hot end are just barely larger than the filament it has no choice but to continue pressing down on the liquid filament below.

With a narrower diameter filament, though, the filament can heat, soften, then travel backwards along the sides of the hot end and cool in place, jamming the hot end, or at least preventing an even continuous flow of plastic.

Some hot ends will accept a small Teflon tube that takes this space up and allows you to do this with fewer issues, and if you like to tinker you can experiment with this, but be prepared to learn a lot and fail a lot as you find out the hard lessons of hot end design.

Generally you should upgrade your entire extruder and hot end setup to the size you want to use.


I can't really follow the information provided but I've read that Creality had some issues with saving settings if there was no SD-card in the printer when saving, could this be the issue?
I would recommend trying another firmware (not from Creality but something like Smith3D.com (https://smith3d.com/ender-3-v2-bltouch-firmware-installation-guide-by-smith3d-com/) which I've used before with success.
If you're willing to pay for precompiled firmware (and support the Marlin developers) I can also recommend https://marlin.crc.id.au/ (which I use now)


Under extrusion, looking for specific information

Your filament is 1.75 mm, but you specified 1.6 mm in the Filament option Diameter (mm).

Furthermore, your layer thickness is very small (0.06 mm), why not try 0.20 mm first; a thicker layer will cause a higher extrusion flow. It could be that the print speed is too high for the low layer size.

Your initial layer 0.3 mm is also high, the maximum for a 0.4 mm nozzle.

Why did you change so many parameters? The standard values work pretty well.


I have a bunch of solutions to this problem but I'm always looking for additional ideas. I usually start by slicing as much as possible off with a hobby knife. The more than can be removed before sanding the better.

For big prints I like big generic sandpaper sheets from the hardware store. Starting with the highest grit and moving down. Make sure you're discarding your sheets when they get totally gunked up (which can happen pretty fast) or you won't get much done.

For smaller nooks and crannies I have a set of needle files. They do a pretty good job clearing out screw holes and smaller features on printed sculptures.

I've also had some success sanding with my Dremel when it comes to annoying stuck on supports or other imperfections. Having some horsepower behind your sanding can be a nice break. I've also seen the wire brush attachments used for finishing Bronze and Copper-fill prints. Just keep an eye on your speed or you'll sand a hole in your print.

Lastly (and one I haven't tried) are these sanding sticks They were recommended by a friend and look like they would be pretty easy to use/swap out used sandpaper.


There are pro and cons for leaving the sticky protection baking paper on the slate of glass:

pros (for not glueing it):

Can be removed more easily in the future (the collant is not easy to remove, requires a solvent and elbow grease)
Can remove the slate of glass to put it in the refrigerator to loosen stuck prints

cons:

Need for binder clips that may cause nozzle collision and decreases bed size (unless you use kapton tape to fix the bed)
Backing paper adds another layer of insulation (unless you remove it and all the goo)


Can I schedule prints to start at a specified time?

There are a few options to delay starting using either the OctoPrint environment or directly use G-code for this.

The use of G-code is probably the most simple for you to implement. The G4 command defines a "dwell" or pausing period for the next command to start:

Depending on the firmware you use, you can use the P or S parameter to specify the pausing period.

To pause the print job (for 1 hour) you need to insert the following line as the first line of your G-code print file:

G4 P3600000 // One hour pausing; defined in milliseconds

or (if your firmware supports)

G4 S3600 // One hour pausing; defined in seconds

Other solutions may include the adaption of the OctoPrint controls menu structure or use of the REST API of OctoPrint. These options are more difficult to implement.


What can cause a sudden and dramatic loss in the inter-layer registration of my prints?

There are many factors, here are a few things to check:

I'd first suspect filament feeding.  This type of ridging can be caused by a filament coil that is binding occasionally, or a filament that doesn't have an even diameter or volume per length.  Binding within the filament feeder and feeder tubes can also be a cause. Bubbles in the filament, or sometimes a mismatch between the filament ideal temperature and the head temperature could create results like this, but it probably wouldn't vary so much between the layers.

Next I'd look at the print head.  If it has blockages, or poor temperature control this could result.

Lastly, I'd check the mechanisms - disconnect the motors and see if all the carriages slide smoothly without any binding, particularly the Z axis.  It doesn't look like you're missing steps, but binding here may result in greater backlash, which could result in similar ridges. Make sure any belts and gears are tight.


How do you assure that you print layers that bond correctly?

I think the reason why the large cylinder is breaking much easier than the smokestack would is because of leverage. If you print the same cylinder at a much smaller scale it might be more difficult to break it. Think of taking a wooden stick, if you try to snap it by holding both hands near the center, it would be difficult but if you push on the very ends, the leverage will make it easier to snap. I have the tug boat on my desk right now and I was unable to snap it, instead I broke the cabin section just right above the steering wheel.

Now to answer your question. One of the faults in larger prints having weak layer adhesion could be a number of things. I think a common fault is under extrusion. If the nozzle has a high enough gap from the previous layer and it extrudes just enough filament to touch the layer but not necessarily push it snug, it could be a weak bond. This is like tape, usually when you want to make sure it will stay stuck, you press hard and rub it in. So I imagine filament shouldn't loosely flow onto layers but instead be pressed hard against the previous layers. Visually this is hard to judge but I noticed getting my first layer very close to the print bed makes every other layer stick very stronger on the previous one. You get a small skirt on the first layer but it does tend to give me a stronger bond between layers. You can easily slice off the skirt with a blade. Increasing the extrusion multiplier could give the same affect without needing to adjust bed height/leveling, but this can end up giving you some nasty walls.

Another thing I recommend is to check your Z-axis. This is difficult to measure and best to find out by print quality on tall structures. On my first printer I had the issue where my threaded Z-rods would bind and cause one of the two rods to get a slight bit ahead. This caused a layer split focused on the side opposite of the faulty rod. This made many prints very prone to breaking at that point. I had to rebuild my Z-axis assembly to correct this.

Print temperature can help, try raising it up by 5 to see if this improves the bonding.

Lastly, try another filament. Filament tends to go bad due to moisture exposure, that is why usually you receive it airtight with a small bag of silica to absorb moisture. If I use filament which has been sitting out for months, just squeezing my part separates the layers in almost a slinky kind of way.


How to properly use Polyisocyanurate (PIR) foam with the heated bed?

An alternative solution that is used with some Kossel Mini models, is a simple cardboard covered with aluminum tape (docs).

This solution has the added benefit of actually improving heat-up time, since the reflective surface of the aluminum tape reflects the heat back into the bed, instead of getting absorbed.

It is also a very simple solution, without costly materials. I guess mounting it properly could be an issue depending on your printer, but this is a fine solution for the Kossel models, at least.


It is typical for a 3D printer to be able to manage one-half the width of the nozzle for unsupported layer printing. This frequently calculates out to a realistic 45° from the start point.

If you are getting 1 mm extension from a 0.4 mm nozzle you are doing well. It's possible that the layers are not strongly bonded at the point of extension from the vertical wall, but are then strengthened by the layers printed above, if they do not extend excessively.

If your part is designed well, the extension will be distributed gradually over more than one layer, allowing that 1 mm extension over 2.5-3 layers without impacting the appearance of the model in an excessive manner.

The above does not apply to bridges, as it involves a different dynamic for the printer/slicer software.


What does nozzle size affect besides line width in, e.g., Ultimaker Cura?

Searching the CuraEngine source, the only places I can find where nozzle size is used directly involve some arcane logic for merging of infill lines, such as:

https://github.com/Ultimaker/CuraEngine/blob/05e93dabce9e863b8742fd69ed87717e1594e7a9/src/MergeInfillLines.cpp#L124

So essentially, yes, nozzle size mainly serves as a default value for the line width settings.

However, in general it's not always possible for line width different from nozzle size to be honored.

For line widths smaller than the nozzle, motion along a path where the material being deposited has proper adhesion is required to stretch the material and prevent it from retaining the width extruded from the nozzle, and small lines already printed are likely to be damaged by the nozzle when attempting to print additional small lines in their vicinity. In particular, you won't be able to print small details significantly below the nozzle size just by extruding less material.
For line widths larger than the nozzle, compression against an existing surface is required to prevent the extra material from just sagging down rather than expanding horizontally. In particular, line widths wider than the nozzle are unlikely to work right in the presence of overhangs.

Also, as noted by Tim Kuipers in comments, there are places outside the source, but rather in the json-based configuration tree, where nozzle size plays a role in the defaults and warning ranges for other parameters. Those are mostly line widths, but

  The nozzle size can affect the values of the following settings besides line width in fdmprinter.def.json: Outer Wall Inset, Outer Wall Wipe Distance and Minimum Support XY Distance. Other than that it only influences the conditions under which setting-values give you a warning.


Why turning off model cooling for first layer?

Filament expands as it gets hot. Cooling the filament will make it shrink, so cooling the filament deposited on the bed can lead to adhesion problems and warping of your products. This is exactly the reason why you use a heated bed (the delta temperature is smaller). So keep the cooling off for the first layers and you'll be fine.

Additionally (having answered the question for not using cooling air for the first layer), I would like to add that sometimes you won't need any cooling at all (for other layers), or very little cooling.

Please do note that some filaments do not like to be cooled down too fast; this may lead to weaker layer bonding or other issues. E.g. POM filament will harden very quickly when cooled causing the nozzle to bump on the quickly hardened filament knocking the product over. Also I found that too much cooling air when using PETG leads to "string-cheese" products caused by insufficient layer bonding. ABS is reported to be even more sensitive for cooling (shrinkage during cooling is higher than of PLA or PETG filaments); a frequent advice is not to use filament cooling when using ABS filament.


The second motor is hot. And the third is very hot. I can not even touch it.

This is to some degree, completely normal and expected. From the datasheet for a typical NEMA 17 stepper, the rated temperature rise is 80 °C above ambient and the maximum operating temperature is 130 °C (implying an ambient temperature of 50 °C). It is normal that stepper motors (in general) get a bit hot.

"Too hot to touch" is still relatively cold. 60 °C is already too hot to touch, and that's only a 40 °C rise above a 20 °C ambient temperature.

You can reduce the temperature rise of the motors by reducing the current they receive. The stepper driver has a small potentiometer that can be turned to adjust the current, but keep in mind that doing so will also reduce the torque of the motors and thus they might skip steps if you reduce the current too much.

Technical details: Note that stepper motor drivers used in 3D printers are constant current drivers, and the little potentiometer controls the current. If you had not paid much attention to this potentiometer, the drivers might all have been set for the same constant current of $1.0\ \text A$. The stepper driver would (to achieve the same constant current) send a higher voltage to the higher resistance motors. This would imply a power dissipation of $2.4\ \text W$ in the Nema 17, and a power dissipation of $10.5\ \text W$ in the small stepper. $2.4\ \text W$ in the Nema 17 would only heat it up by about $20\ °\text C$ above ambient. A dissipation of $10\ \text W$ in the small stepper, which also has much less surface area to dissipate the power, would heat it up by a lot (and probably, given that you didn't fry it, the current was set lower -- or a technical peculiarity limited the current given that the motor likely also has very low inductance).


How easily can I remove/replace the nozzle of the prusa i3?

Assuming you have a typical setup:  nozzle threaded into heater block, use a socket wrench on the nozzle and any wrench or vise-grip on the block, and unscrew the nozzle.  Now, if your system is fully clogged, you may want to heat the head to melt all the residual gunk (which otherwise will strongly resist your unscrewing force).  Obviously take care not to burn yourself if removing the nozzle while hot.

Alternatively,  don't bother removing the nozzle.  Raise the extruder as high (Z-axis) as you can, heat, and use a properly-sized stiff wire to ream out the nozzle.  You can use the back end of a microdrill bit.  Hot or cold, you can use the drill itself to ream, but be very cautious as you may widen the nozzle itself doing this.

I should add that you may well have gunk in the feeder tube, and that's considerably wider diameter. Remove the nozzle and gently drill out the feeder with a matching drill.


After some testing, Fusion does have a category to put in an Area parameter [edit -> Parameters ->] for Area that takes measurements in acres and circular mil but no useful measurements such as square centimeters or square inch. One circular mil is defined as a circle with a radius of 1/1000 inch, or 0.0254 mm, for an area of $5.067×10^{−4}\text{ mm}^2$.
However, defining the area of an item isn't (currently) straightforwardly possible: areas are not defineable, and with the obvious lack of possible parameters (square metrics and anything but super tiny or super huge) it doesn't seem to be planned. The best you can do is for bodies that you know the formula for the area in the following fashion:

Here, the left measurement (d2) is 1 mm. The parameter area is 10000 circular mil. Since we know A=d1*d2, we can go A/d2=d1 for a rectangle.


Basic Spinning Top Prints Fail in Same Location

To me, it looks like your G-code induces an incomplete layer of support on the still standing piece, which later down leads to the print failing.

Re-slice the whole thing.

As a matter of fact, I would cut the model in its widest place and print both with the large face flat on the surface and glue the two pieces together after printing. That way I can achieve:

no need for support material
maximum adhesion
no surface problems on the transition from the support to the print


Getting 5V directly from the Anet A8 mainboard

The 5V is derived from the 12V supply by a linear regulator (L7805CD, DPAK package with 100 C/W thermal resistance). The maximum you can draw from it (without overheating the regulator) is around 200mA. Considering the electronics on the board are already using some power, the maximum would be around a 150mA fan but this would have the regulator running near its maximum limits.


The previous answer is good, but here's one specific for Bigtreetech.

Install platform.io. I use the command-line interface (CLI)
Modify your marlin files. You can clone existiing firmware for your board from the BigtreeTech Github for your board.
Remove microUSB card from your Bigtree tech board
Plug microUSB card into microUSB reader, and the microusb reader into the computer. You should be able to read your microUSB card
Enter the command in the root directory of your Marlin files: platformio run -e STM32F103RC_bigtree_USB. At least, this is the one for my board. You should have to run this in one folder before the Marlin folder.
It creates a file called firmware.bin in the directory .pio/build/STM32F103RC_bigtree_USB/firmware.bin. Copy it to your microUSB card, replacing and deleting any existing .bin. You can use the name firmware.bin.
Remove microSD card from computer and plug into board.

In your Marlin Configuration.h file, there should be a variable called something like MACHINE_NAME. If you make that name custom, then it will appear in the Octoprint terminal when connecting to your board, letting you know that you have updated the firmware.


Why does the painters tape have to be blue?

read first
When you use painters tape, you need to level your printer with the tape applied. You need to relevel if you change the tape type.
Basics
It's not any blue tape that printers love. There are basically two factors that make a tape useful:

It has to stick during printing.
Its surface has to allow the filament to stick to it.

Let's look at some different tapes and their suitability - from my own experience.
ScotchBlue
The original blue tape is actually ScotchBlue for delicate surfaces by 3M. It has a good surface to stick to and at the same time an adhesive that does not degrade to unsuitability by heating. The delicate surface one is just as good as the all surfaces type. But don't use the outdoor type, it is sealed too much.
FrogTape
FrogTape has an adhesive that has no problems with heating, the surface is sometimes a little smoother. Its green variant is about as useful as ScotchBlue, while the yellow variant is easier to remove - which can be an issue when the printhead is not calibrated correctly.
Generic painters tape
Generic painters tape is a can of worms - there are so many different ones it is hard to describe. I have had very good off-yellow rolls from the dollar store of the 'fine surface' type - as in the tape had a fine surface - and their adhesive was good and didn't degrade too much under heat. The followup roll was a little thinner of material and released under heat so it can be a hit and miss - it's ok for starting out though.
I also tried a roll of UHU painters tape of the easy remove type and it was horrible, as it didn't want to stick after the nozzle went over it once even on an unheated bed.
Generic blue colored tape
I even tried two blue colored tapes from different dollar/hobby stores. One was ok-ish and had a similar result as the good dollar store tape in look, but left a blue shadow on the base of the print after two or three prints. The other was showing similar behavior to other mild-adhesive/easy peel tapes.
Conclusion
It's not color that matters, it is the formulation. If you must use blue tape, spend the extra bucks for quality. Some bloggers compared other tapes, tested ScotchBlue vs Kapton, discussed the benefits of either, discussed the ScotchBlue tape in depth.
While in general, I prefer to print on the surface of my (blue) BuildTak (clone), I occasionally whip out painters tape on an unheated surface for very delicate prints: I remove the print together with the tape from the surface, which allows better handling. Sacrificing a layer of tape only costs some cents after all while breaking a print is hours and filament for much more  money wasted.


What are the "magic numbers" on a Monoprice Select Mini?

The "magic numbers" are optimal values that work particularly well for the layer height.  Michael O'Brien derived these numbers by reverse engineering the mechanics of the Z-axis stepper motor.

Using these values as your layer height will generally improve your print quality over using round layer heights such as 0.15, 0.2, or 0.25 by eliminating quantization errors.

To see an example of this, print a copy of 3DBenchy at 0.15 and 0.175.  On the 0.15, you will see some wavy patterns on the curved bow portion compared to the 0.175.  This is the result of inexact rounding.

Layer Height (mm)
0.04375 (results may vary)*
0.0875
0.13125
0.175
0.21875
0.2625
0.30625


Cura slicer, enforce Z move before layer change

To lift the head to prevent the nozzle to tip over your print you could use an option called Z hop in Cura. Just enter `hop' in the search box on the right side to make those options magically appear (in a recent version of Cura, e.g. version 3.x.x).

Other than Z hop there is no default action, or series of commands, per layer to be specified before the start of the layer. There are 2 other ways to circumvent this:

The first is saving you G-code to file and open the file in an advanced text editor (e.g. Notepad++). With a (recorded) macro you can find the words ;LAYER:, which are inserted by Cura before each layer starts, and insert a pre-copied list of commands that set the movement in relative mode, move Z up 2 mm, set into absolute mode again. When the next layer starts the extruder goes to the layer start from a 2 mm rise.
Write a plugin for Cura to post-process (C:\Program Files\Ultimaker Cura x.x\plugins\PostProcessingPlugin\scripts) the G-code file to inject the code to Z hop before the start of every layer, or a plugin that adds a new option and/or category to the slicer settings sidebar of the GUI.


Same menu, different location in the sub-menu (at the bottom):

As T.M. states in their comment, see Poisson mesh reconstruction on StackOverflow:

  MeshLab 2016 now uses the new version of the Poisson merging, and the
  filter is called:

  Screened Poisson Surface Reconstruction

  it is in the same submenu, on the bottom. The relevant parameter
  (octree depth) is called Reconstruction Depth. It is now possible to
  merge multiple layers at once, without flattening them beforehand (as
  before). If source layer(s) have color, the result will be colored
  too. If you want to have the same result of the old version, put 0 in
  the "interpolation weight" parameter


In agreement with what Akriss said, pretty much all "super" glue is CA (cyanoacrylate) glue, which is soluble in acetone. PLA itself is does not dissolve in or react with acetone, but the pigments, additives, etc. likely do, so you should wipe with a paper towel or cloth (the latter might be better to avoid getting fibers stuck on the glue) soaked in acetone rather than pouring it over the piece or submerging it, to limit the effects. Also, test first on a scrap piece printed with the same filament to ensure the results aren't unacceptably bad.


Ender-3 Pro - PLA mid-layer warping (layer separation) - salvageable?

One hundred percent infill is not necessarily stronger than lower values. By having such a high infill figure, the forces on the model as it cools are magnified and not in a particularly good manner.

Consider that you could use twenty to thirty percent infill to get the strength you require for this application, saving filament and time for the print. You've not noted how many wall layers used, but for increased strength, four to five would make for a very strong model.


The fuse rating is same as described on the board - so that shall be no issue with it.

My main concern is why the fuse is down?

Was there a short-circuit? As this is mains fuse - that suggest a big-bang, so, please check carefully hot-end and bed heater connections before restarting the device, to avoid replacing another fuse.


How are things like a USB casing designed for 3D printing?

3D printing provides a faster method for prototyping and have always been labeled as prototyping machines. Until recently, it has been rare to see 3D printers used for "mass manufacturing".

Yes, most mass-produced products start the manufacturing process with a 3D model. 3D models can be created in many different applications such as Solidworks, AutoCAD, Unigraphics, Blender, even Sketchup just to name a few.

In product development, the 3D model will then go through prototyping. Rapid prototyping can be done using a 3D printer by utilizing cheap materials and almost no labor cost.

Here are a few costs that can be associated with the different prototyping methods.

Traditional Prototyping

(Typically involving "traditional", subtractive manufacturing methods such as CNC mills, lathes, routers, etc.)

CAM programming
Fixturing
CNC Machine Setup
CNC Operating/Labor

Rapid Prototyping

(Typically involving a 3D printer or other additive manufacturing methods)

Model preparation (for slicing)
Printing Operation
Object post-processing

Removal of supports
Curing/Cleaning of part (for non-FDM/FFF printing methods)

Once a prototype is produced, the designer will adjust the 3D model accordingly based on results of the prototype. This process will be repeated until the prototype is adequate for the purpose of the end product.

When the product design is ready for mass production, it will go through traditional manufacturing methods such as:

CNC Machining (subtractive)

Mill
Lathe
Router
Laser
etc.

Injection Molding
etc.


Can general purpose polystryene (not HIPS) be used for 3D printing?

In principle, it should work fine as a filament, since it's used extensively in the plastic extrusion industry, but I don't think you'd get great material properties out of it. ABS and HIPS incorporate polybutadiene into a graft polymer structure for a very good reason: the butadiene sections in the long molecular chains kind of "stick together" as a distinct solid phase to produce what amounts to micro-bubbles of rubber inside a matrix of hard styrene or acrylonitrile-styrene plastic. This compound microstructure is what gives HIPS and ABS favorable impact toughness and some minor flexibility.

The flexibility is important -- the stiffer a filament is, the more it will tend to warp while printing. Based on chemistry alone, I would expect styrene to be somewhat more prone to warping than ABS. And it would certainly be more brittle. So there doesn't seem to be much reason to use it as filament.

Interesting sidenote: PLA/PHA has very favorable mechanical properties because the PHA forms a very similar flexible microstructure inside the hard PLA matrix. PLA/PHA is good stuff because it mimics ABS and HIPS!


Is there any 3D-printing software that supports Raspberry Pi?

The answer is "yes", but it depends on what hardware you have, what operating system you are using, and what software you want (or need) to use.
I have a Raspberry Pi 4 with 4GB of memory, and I am running a 32-bit version of Raspberry Pi OS. I have been able to install the following software from the Raspberry Pi OS repositories, but not everything is working "out of the box":

Blender 2.79 (starts, but not tested)
Cura 3.3.1 (crashes on startup)
FreeCAD 0.18 (crashes when opening a new document)
PrintRun (PronterFace) 1.6.0 (working)
PrusaSlicer (Slic3r PE) 1.39.2 (working)
Repetier-Host 0.85 (crashes on startup)
Slic3r 1.3.0 (working)

I have been able to download the 3DBenchy from Thingiverse, slice it using Slic3r, and PrintRun (PronterFace) is currently printing it on my Tronxy X1.
I will update this answer if I can get the other stuff working, since I would quite like to use a Raspberry Pi for 3D design and printing. If I can get FreeCAD working, I shall be happy, and OpenSCAD would be a welcome bonus, but I don't think that it has been ported.


How to offset my probe so it's not hanging off the bed at 0, 0 position when printing

It is not a problem that the sensor is not above the build plate during printing as long as it is above the build plate during the auto bed levelling sequence.

Homing does not necessarily need to be the (0,0) coordinate. Usually, a printer homes on the endstop switches, from that coordinate an offset is defined in the firmware to move to the origin. This implies that (depending on the position of the sensor), the sensor may be outside the bed area when the nozzle is at the origin (0, 0)). Therefore, similarly, you need to tell the printer the location of the Z sensor with respect to the nozzle position in order for the printer to keep the sensor on the bed when levelling by setting boundaries for the sensor to reach.

E.g. for Marlin firmware the offset from homing to the bed origin is defined for an Anet A8 by:

#define X_MIN_POS -33
#define Y_MIN_POS -10

The values you should use need to correspond to the actual offset from the homing point to the origin of the bed (0,0).

When using an auto bed leveling sensor like you are using you should consider this remark:

  If using a Probe for Z Homing, enable Z_SAFE_HOMING also!

Un-comment the proper line in the configuration file to read:

#define Z_SAFE_HOMING

This will make the printer aware of the sensor, and home Z in the middle of the bed (default behavior, but can be changed), so that your sensor is never off the bed when probing the bed for Z homing.

Furthermore, you need to set the offset values of the center of your sensor to the nozzle center:

 *   Z Probe to nozzle (X,Y) offset, relative to (0, 0).
 *   X and Y offsets must be integers.
 *
 *   In the following example the X and Y offsets are both positive:
 *   #define X_PROBE_OFFSET_FROM_EXTRUDER 10
 *   #define Y_PROBE_OFFSET_FROM_EXTRUDER 10
 *
 *      +-- BACK ---+
 *      |           |
 *    L |    (+) P  | R <-- probe (20,20)
 *    E |           | I
 *    F | (-) N (+) | G <-- nozzle (10,10)
 *    T |           | H
 *      |    (-)    | T
 *      |           |
 *      O-- FRONT --+
 *    (0,0)
 */
#define X_PROBE_OFFSET_FROM_EXTRUDER XXX   // X offset: -left  +right  [of the nozzle]
#define Y_PROBE_OFFSET_FROM_EXTRUDER YYY   // Y offset: -front +behind [the nozzle]
#define Z_PROBE_OFFSET_FROM_EXTRUDER 0   // Z offset: -below +above  [the nozzle]

Where XXX and YYY are your actual values.

And set the boundary of the probing section:

// Set the boundaries for probing (where the probe can reach).
#define LEFT_PROBE_BED_POSITION 15
#define RIGHT_PROBE_BED_POSITION 190
#define FRONT_PROBE_BED_POSITION 15
#define BACK_PROBE_BED_POSITION 170

Note that the values should match your bed size!

And:

// The Z probe minimum outer margin (to validate G29 parameters).
#define MIN_PROBE_EDGE 10

Details on setting the boundaries of the bed to keep the sensor on the bed is described in question "How to set Z-probe boundary limits in firmware when using automatic bed leveling?".


Printer doesn't lift Z between each probe

In my Pins.h folder turns out I needed to put a x-max pin. I hadn't defined that so it was randomly reading it as high. my printer thinking it can't go higher was freaking out basically :) this explains the other strange behavior i was experiencing!


It's totally possible to achieve but the result vastly depends on your painting skills and your spray paint quality.

Your can look at this page for a concrete example.

How it compares to stone filament is fairly subjective though. Painting a 3D print usually breaks down in 3 steps :

Smoothing out the lines.
Achieved by either sanding the print or using acetone
Apply coating.
Ensures a better adhesion for the paint
Apply spray paint

If any of these steps are neglected, the final result won't look as good as using stone filament. However, if the quality of you stone filament is really bad, painting will offer a better result.


Rejuvenate is probably a bit of an exaggerated term. The number one adhesion suppressor is grease. The stuff that comes off of the fingers used to handle the sheet. Even if you are careful and only handle the sides, the grease will be carried to the center of the plate next time its cleaned with less aggressive solvents.

Isopropyl alchohol does break down grease but not to the extent that acetone does. Acetone also attacks plastic particles that accumulate on the print surface over time.

PEI is resistant to a wide array of chemicals[1] including acetone but it can become brittle if exposed to it too much especially when hot so acetone is not recommended for daily cleaning.

[1] Ultem Product Broshure table 4-3


Printer cover for noise abatement, cleanliness, temperature control

If you want to have an enclosure without actually building one, you can try a server cabinet. Just take out the server racks and use it as an enclosure. And, as there are many server cabinets available, you could probably find one that suits your needs. Currently, I have my FlyingBear P902 3d printer enclosed in a server cabinet. And, although the doors and removable sides might have air gaps, you can always just tape that off (or use an insulation strip). Hope this works.

You could also look at this website: Perfect 3D printer enclosure for Prusa i3 MK3


Yes
You need to do a two-step post-processing:
Washing
This is basically as easy as taking the print and dropping it into a vat of Isopropyl alcohol and vigorously shaking it to get all the liquid resin off. Careful, the resulting contaminated IPA is to be treated as toxic waste.
The reason why you wash the print is to make sure no resin stays on it and cures, distorting the print or altering the measurements.
Post-Print-curing
The next step is just having the item sit in UV light to cure thoroughly, which means either having it sit outside in sunlight or under a UV lamp. Under sunlight, it might take a few hours, under a UV lamp, it depends on how thick the object is and you might need to turn and rotate the printed part. Note that some resins, especially transparent ones, can change their coloration when exposed to sunlight, both during or after curing.
Curing is done to ensure all the resin is fully cured and get the full stiffness out of the print - sometimes prints are still somewhat malleable before giving them time to cure.


If you take a kettle lead with a wall plug and cut off the other end, it will expose 3 wires: earth, live and neutral. These are color coded depending on your country, usually earth is green (possibly with yellow stripes), neutral is blue, black, grey or white and live is brown, red or black.

The SSR should have 4 terminals: 2 terminals for the switched load (which are interchangeable) and 2 terminals that connect to your electronics, which should be marked negative and positive. These terminals should connect to the negative/positive heated bed output of your electronics. The terminals of the SSR should be clearly marked, and you can verify which terminal is what from the SSR's datasheet.

Typically, your heated bed will have two wires for power (which are interchangeable). One of the wires should be connected to neutral. The other wire should go to one of the load terminals of the SSR, while the other load terminal of the SSR should connect to the live wire. It is also acceptable to do it the other way around (neutral to the SSR and live directly to the bed) but this is slightly less neat.

Finally, and this step is extremely important, the earth wire of the plug has a protective function: should something fail, metal parts of your printer may become electrified, and shock you when you touch them. To prevent it, you should electrically connect exposed metal parts of your printer (such as the frame, heated bed plate, power supply case, etc...) to earth. This provides a path for the current to flow (and trip the protective RCD breaker) should something go wrong.

I would further recommend that you protect your heated bed (particularly if it is a high power model) with a bimetallic thermal switch. These are available in a variety of ratings, and will switch the power to your heated bed off when it goes over a certain temperature. This switch should be wired between the relay and the heated bed, and be mounted on the heated bed so it makes good thermal contact. If you plan to print with the heated bed at 110C, you might get a 120C or 130C thermal switch.

As mains voltage can be deadly, you should take appropriate precautions: never work on the printer while it is plugged in, cover any connections (in particular, make sure you buy or print a cover for the SSR's terminals and wrap solder joints in heat shrink or electrical tape) and always treat wires coming out of the SSR as live (even if it is switched off, some current can still flow).


Cura: How to prevent my 3D printer from auto cooling after prints

In CuraEngine's FffGcodeWriter::finalize method, G-code to zero the bed and enclosure temperature is only written if the machine profile defines a heated bed/enclosure, so you could in theory avoid the cooldown by telling Cura your machine doesn't and putting the heatup commands in your custom start gcode instead of letting Cura emit them itself. However it unconditionally zeros all of the hotend temperatures, and does this after emitting your custom end G-code, so you can't even turn the hotend back on from there. The only way to undo Cura's insistence on turning it off is with some sort of postprocessing.


I have recently looked into "print outer walls first" in an attempt to make the seam vanish. But turning that setting on creates a webby structure on the following area for my printer.
Turning the setting off again (and reducing the outer wall speed to 30 mm/s) completely eliminated the ringing again.


What kind of filter do I need for the enclosure of a 3d printer?

For the most part, a consumer 3D Printer will only need proper ventilation when using potentially harmful materials such as ABS. (See duplicate question). If you're printing with primarily PLA, then you don't need to worry. I print mostly with ABS and keep my machine close to a window and I haven't experienced any issues.


I've had better luck with fonts that are heavier, usually sans-serif, and usually bold-face. All-caps can help, too, if it makes sense at all for the text. Impact is one widely-available example, though it's far from perfect and rarely has the look I want. I also usually need to turn on the "Print Thin Walls" setting in Cura when handling smaller text.

When looking at how small you can get, we'll start with font sizes. It would be easy to get lost here in a discussion of points and measurements. The thing is, font sizes describe the vertical height of the characters. For 3D printing, I believe you'll do better paying more attention to the horizontal width of your text. Most characters are taller than they are wide, so if you can produce legible horizontal features, you can probably handle the vertical features, too.

I'll use the letter "H" as an example here, because it shows the full size of the box for a typical character. Specifically, since I'm talking about horizontal features if you look at the bottom of the H, it has a three sections: leg, then gap, then leg. Also notice the gap is about 3 times the size of the legs (you can see this better if you zoom in close). This varies by font, but 3:1 is good average ratio. That gives us 5 units of width for the character itself. Additionally, you want to allow some spacing between individual characters; not every character needs it next to every other character, but I find it useful to allocate a 6th unit here.

Now consider those 6 units in the context of your nozzle size. With a typical .4 mm nozzle, that means the smallest size character you can legibly produce is about 2.4 mm across. Of course, most fonts are not monospace, where a character might be larger or smaller, but I believe this makes a useful average. Count the number of letters in a line of text you want to print, multiply by 2.4 mm, and that's the minimum amount of horizontal space you need.

If you really want to push things, a font specifically designed for 3D printing should theoretically be able to work in terms of 3 nozzle units wide + an extra gap between certain letters. But this is all theory, and for the minimum of what's possible. When you also start to think about what actually looks good, especially if you want to show features like serifs, the real world can really mess this up. In practice, I've found I need to go significantly larger even than the 6 unit / 2.4 mm option... but maybe I've just used the wrong font. You can always try a test print of your text in a small rectangle, to make sure it will be legible before using in a larger object.


Glue for attaching PLA pieces to titanium

I've been a fan of epoxies for unusual adhesion problems. I found on Amazon a product with titanium in the name, but there's a caution regarding polypropylene plastics.

PLA is not of that family of plastic, which gives it a good chance of success. Epoxy is typically more viscous than cyanoacrylates, giving you a bit more control of the application, but also creating the need for care with "ooze-out."

The big glue company, Gorilla, also makes an epoxy that includes plastic and metal in the adhesion listing.

As PLA is somewhat sensitive to heat, one would consider that fast-cure epoxies generate more heat than slow-cure epoxy, but the amounts you'll be using are not likely to create enough for concern.


How to choose printer with dual extruder?

As you suggest yourself, ordering test prints of some model is one way to do it.

3D Hubs and MakeXYZ allows you to get your model printed by hobbyists and small businesses for a fair price. Both sites also allow you to order prints based on printer type, which I believe is what you may be looking for.

On 3D Hubs, visit on of the trend reports, and select the printer you want a sample from. Similarly, on MakeXYZ, search local makers for your desired printer.


PLA itself should be safe, at least chemically, but there's no guarantee that additives in a particular filament manufacturer's material are safe. From this standpoint it would be best to use an uncolored "natural" (comes out translucent but cloudy when printed) PLA from a manufacturer who documents that it has no added ingredients. It's also plausible (not saying this is necessarily the case) that there's fine particulate matter produced by heating or in the extruder gear that ends up on the surfaces.

However, in the bigger picture/XY-question, it's unlikely that printed masks provide safety against viral transmission. Especially with a rigid material like PLA, they're not going to make an air-tight fit with your face, and they're likely not air-tight themselves even if they do (due to imperfect extrusion, slight gaps between layers at least intermittently). This could perhaps be mitigated by using a separate edge material to make a tight fit with face, and sealing the print like you suggested. However, once you make it air-tight, it's unsafe for another reason: it's a suffocation hazard! Just because you insert a filter to breathe through doesn't mean that you're actually going to be able to breathe through it properly.

Naomi Wu a.k.a. Sexy Cyborg (well known for working with Creality, open source/OSHW compliance in China, and popularizing the Ender 3) has done a number of twitter threads on what the dangers are and why it's unsafe and irresponsible to be creating air-tight 3D-printed masks if you're not qualified for designing this type of device. Here is one. A highlight:

  This results in CO2 buildup. After about 30 minutes your plastic mask, if actually airtight and strapped securely to your face will, before you can take it off, kill you- very peacefully. You'll just slump over and go to sleep, but you'll still be dead.


Monoprice select mini V2 displaying '999' degrees for build plate temp

You get this temperature reading when there is broken wire. Not owning this printer type, can't you switch out the bed thermistor for a new one? Or alternatively check if a connection is loose.


What are various types of supports required in slicing the CAD model?

Support structure generation depends on the type of slicer you use to convert your model (STL model file) into printable code (G-code) for the 3D printer. Different options and solutions exist to add support depending on the slicer software applications. Alternatively, you could add your own supports to your models in 3D CAD programs.

Without giving an opinion on the slicer applications, the most commonly used slicers are Cura and Slic3r (both free) and Simplifi3d (paid license). Please choose your software and do some more investigations on setting up these applications for slicing and address your question with a more specific question.


Marlin 1.1.x on Ender 3 changing PREHEAT_1_FAN_SPEED has no effect?

Apparently, I forgot a critical step:

While I have completely reconfigured the LCD menus, setup custom 25-point mesh leveling, changed a bunch of other numerical values, and flashed the firmware dozens of times, certain values will never be updated unless you remember to initialize the EEPROM after the flash!

Honestly I kinda wish they would make it all or nothing but I guess there is limited space so particular things take priority.


When I attempt to calibrate extruder steps the increased values don't correspond to physical increases

Mechanical?

You basically answer your own question that there could be a mechanical issue.

If 93 steps gives you 38 mm, to get to 100 mm, you need to divide 100 by 38 = 2.63 times. This implies that you need 2.63 x 93 = 244.7 steps/mm (not 149.73).

You even tried close to 400 steps per mm to see you are not extruding 100 mm of filament. This implies that you are either missing a lot of steps (increasing the stepper current or increasing the temperature of the hotend would help out) or the extruder gear slips on the filament (increasing the pressure on the extruder gear and filament could solve this).

Or not mechanical?

Furthermore, it could be another issue than mechanical. If your extrusion rate is too fast, the stepper might not be able to cope the high speed and miss steps. I have had this before with a too high of a retraction speed.


What is causing these artifacts when the extruder moves in one direction?

In case of such difference in printing in different directions you can check if;

for x and partially z axis

filament is blocked and cannot be pulled as it should
spool is blocked

for x and y axis

rods on which caret/HB is sliding are parallel
timing belt idlers are parallel and they are in a line

Shape of the nozzle or its perpendicularity should not be the case as it's hot and it wipes layer itself.

You can also check if it's not an issue of cooling fan. It can vibrate as such.

Eventually it could be an issue of cooling itself. Let's assume you have cooling fan at the back and it pushes air to the front then when caret moves from the front to the back then cooling time is longer than when the fan goes in opposite direction.


Distortion calibration on XY plane in Repetier

Skew distortion in deltas means there is something physically wrong with your printer build, such as the towers not being evenly spaced or being tilted. The first thing you should do is confirm the mechanical build -- measure the distance between towers, angles between towers, parallelism of all three towers, and perpendicularity of all three towers to the bed. If you post photos of your build, we might be able to provide more specific advice.

If you can't get the mechanical issue sorted, it's possible to calibrate out some specific build errors (like skew due to uneven tower angle), but that's nearly impossible to do "by hand." You really need to use a Z probe and auto-calibration sequence such as in Rich Cattell's Marlin fork or dc42 RepRapFirmware.


Using multiple infill types within one model

To achieve additional localised stiffness, you can also insert small voids (gaps) inside the model. These become double thickness walls once sliced and can be used to support things like screw holes.

See the 'negative' parts used with a cube, and the sliced result here:


What pins do I use for UART control on a RUMBA board for tmc2208?

The RUMBA schematic is available on the RUMBA wiki.

From the schematic, I see that UART3 (with +5V logic levels, not RS232) is presented on the EXP3 connector.  I don't know if Marlin firmware can be controlled through a UART other than UART0, which is converted to USB through an FDDI chip.  The Arduino bootloader is not expecting another UART, so you may still need to program it through the USB port (and UART0).


Can I repurpose most of the components of this Prusa clone for a Delta?

Stepper motors
For equivalence, 4.8 kg⋅cm is 0.471 N⋅m or 47 N⋅cm.
Looking at the RepRapWiki - Nema17, the most common steppers are:

Kysan 1124090/42BYGH4803 (54.0 N⋅cm),
Rattm 17HS8401 (52 N⋅cm), and
Wantai 42BYGHW609 (39.2 N⋅cm).

The Kossel that you refer to is of a similar size to the Kossel XL. Again looking at the RepRapWiki - Kossel, the recommended stepper is the Kysan 1124090 Nema 17 Stepper Motor which has a Holding Torque of 5.5 kg⋅cm.
So, without knowing the exact make and model of your stepper motors and assuming that the specifications for your stepper motors given in the Prusa clone are correct, your steppers are not as strong as those recommended (apart from the Wantai). However, the recommended steppers may be over-engineered and provide [much?] more torque than is strictly necessary. After all, the holding torque of your steppers isn't that much below the recommended values.
If I were you I'd build the Kossel using your steppers and it might, in all likely hood, work out fine. FWIW, I have used the Rattm 17HS8401 in my Kossel Mini and Kossel XL. I got them on eBay and were quite reasonably priced.
You should probably read this article, RepRapWiki - Choosing stepper for a delta. Whilst no concrete values for holding torque are given, this is interesting:

A good practical setup
The Fisher, a small delta printer was designed by late RRP company. As for all their printers, they were using small and compact steppers with a torque of 2.2 kg.cm. This is lower than most repraps but is sufficient if there is no mechanical problem (friction).
These small motors have a low nominal static torque, but they also have a low inductance (2.5 mH), while due to their small size, the nominal current remains reasonable (1.2A).

as is

High inductance motors
You find on the market steppers sold for 3D printers, with a torque ranging from 2.6 to 4.4 kg.cm and a current of 0.4 A. This low current appeal builders as it make the electronic driver heating much less.
However, it came at a cost, which is a very high inductance which varies from 30 to 35 mH. That means these motors are totally incapable of any speed. They are unusable for a delta and a bad choice for another printer. As an example, a 4.4 kg.cm motor wired for this low current, while having a static torque twice the Fisher motors, simply cannot reach the maximum speed used by the Fisher, effectively having a near zero torque over a given speed. Same motors with a winding giving a nominal current of 1.5 to 2 A will be more usable.

Controller
Also, yes, RAMPS is fine for the Kossel, although the firmware calibration is obviously different, as it is a delta and not cartesian printer. For calibration, refer to How do you calibrate a delta robot 3D printer?.
Although, as Scott Lahteine states early on in this video, How it's Made: The Marlin Firmware!, using an 8-bit controller for delta printers is pushing their capabilities somewhat.
Extruder
I'm not familiar with the Flex3Drive, but it certainly looks interesting. I have used the 3325_0, this NEMA-17 motor has an integrated Planetary gearbox with a 52/11:1 ratio. It generates 16.2 kg⋅cm of torque at 1.68 A. I wrote a short blog about it here, The extraordinary extruder.
Building Tips
Also, if you are planning on building a Delta/Kossel, then I'd seriously recommend watching the series of videos on YouTube from BuildA3DPrinter.eu as they are extremely informative and helped me a lot, Build manual Kossel XL & Kossel Mini. I just checked their website to try to see which make and model of steppers they use, in order to get an idea of the holding torque, but they seem to have stopped trading. However, their stepper motor page states the following:

The standard motor for most 3D printers including ours, the 42byghw811
from Wantai Motors.
Holding torque is 4.8 kg⋅cm or 47.1 N⋅cm. Shaft diameter is 5 mm and
stepping angle is 1.8 degrees.

So, to sum up, your steppers should be fine.


Expansion in bottom skin after first layer

OK, let's start with your pictures. Putting aside the expansion in the XY plane, layer 1 looks seriously underextruded (gaps between the lines, even) while layers 2 and 3 look severely overextruded. It would be possible to achieve this with a reduced first-layer flow setting, but you haven't indicated that, and moreover, in addition to looking underextruded, the first layer's lines don't look very flat - they look a lot thicker than 0.12 mm. I suspect if you can take a caliper with resolution greater than 0.1 mm and measure the thickness of the first layer, you'll find it's at least 0.2 mm thick, maybe more.
So, what's happening? You're overextruding by a lot, but have lowered your bed enough to (more than) compensate, giving the excess material in the first layer a whole 0.2 mm or more of vertical space to expand into, preventing it from being pressed against the bed and taking up the horizontal space it should. Now, as soon as you start the next layer, the big problems start. Since the nozzle has only moved up by 0.12 mm, you only have 0.12 mm of vertical space, and the overextruded material gets squeezed out horizontally. Some of it goes down into the gaps between the lines of the first layer. But by the time you get to layer 3, there are no gaps and things go really bad.
What's the source of the overextrusion? Your "esteps calibration". This is not a number you need to calibrate. It's a function of the extruder gear, and for the Ender 3's (including the Pro's) factory gear it's 93.0 (*).
After you fix the overextrusion by putting esteps back to the right value, you're going to need to re-level your bed. If you use the paper method, make sure there is significant tension on the paper and it does not slide freely under the nozzle at Z=0. If prefer using real metal feeler gauges and moving the nozzle to Z=0.1 to level. (You mentioned that you have BLtouch, which I'm not familiar with, but as I understand it you still need to calibrate it due to possible difference in sensor height and nozzle tip height.)

(*) Note that for compressible filaments like TPU and to a lesser extent PETG, compression of the filament in the gear will alter the effective steps per mm of (uncompressed) filament moved. However, rather than modifying your firmware esteps setting for this, it makes a lot more sense to model that as either a flow adjustment percentage or a narrower filament diameter (since essentially that's what it is -- the filament becomes narrower at the point of measurement), since slicing software supports adjustment of these per-material. So, don't touch esteps unless you replaced extruder hardware.


Is it possible to convert a Las /Laz file into an STL or OBJ file?

Given that LAS/LAZ is LiDAR point cloud data, there is a GIS tool called las2tin to convert these files to a triangle based mesh called Triangular irregular networks or TIN by the GIS community. Other GIS tools should be able to do the same, for example ArcGIS.

Once you have the mesh, Google should be able to help you find a way to convert the TIN to an STL. You will need to scale down the STL after creation, as the TIN will probably be at 100% scale.

One example workflow for converting LAS data into an STL is:

Using ArcScene: open DEM > convert to TIN > export to VRML
Using MeshLab: open VRML > export to STL
Using Meshmixer: extrude base > scale to fit standard printing parameters > save as finished STL

More details for the process that I got from Google are available here


Is it possible with current 3D printers to print a sound trace?

Sound Encoding basics
Sound is a compression wave, and any depiction of it has to be an encoding of it. You can encode it so you can recreate the sound using a contraption that oscillates in the right way to compress air again in the right pattern, but you can't just "print it out" like you can scale up a lightwave from the nanometer scale to a visible one as a representation.
Let's take a simple example: a 440 Hz tune is generally considered to be the A4, aka concert pitch a or A440.
It could be encoded in a various ways. The probably oldest is to encode it as a note in violin notation, which then could be reproduced by anyone using a properly tuned instrument. The actual result depends on the instrument used as much as on the skill of the player. Each instrument thus might decode this encoded note differently, based on the physical setup of the instrument. Each instrument automatically creates the appropriate overtones.

In Midi, it is encoded as Note 69 and any machine that can decode a midi file could use this instruction, paired with an instrument to use, to create the A4 that is set for it. In Midi, the mere instruction of Note 69 does cut out skill, but how it sounds and feels comes from the instrument setup - which contains information about what overtones are to be created when playing this note.
For a physicist, the pure sound is encoded as just the notion of 440 Hz and some amplitude to balance how loud it is. With those instructions, he'd be able to set up a device that has these creates a 440 Hz tune. To generate the sound and feel of an instrument, the encoding for a physicist would need to contain all the overtones that are to swing with this one sound.

History of sound recording
Let's look at the very first way of recording sound: The Phonautograph of 1857 used a piece of paper or a sheet of glass blackened and then a membrane move a needle. When the plate would be moved, the needle left a written path. The encoding was done via 2 factors: the setup of the stylus (mainly how long is the arm) and the speed of the movement of the plate. Changing either changed the encoding. A longer arm would record a larger amplitude (making fainter sounds recordable) while faster movement would alter the timescale recorded, allowing to look at short instances and better compare them.
These vibration-pattern records could be used to measure and compare sounds but not be used to recreate the sound, as lines on paper nor scratches in soot are a good way to keep a reading needle in boundaries. it took till 2000 and the use of scanners as well as digital processing to recreate these recorded sounds.
The solution to recreate sounds was found by the Edison Laps in 1877 with the phonograph, which used a piece of thick tinfoil to record the motion pattern of the membrane. Again, then encoding was done via the arm setup and the speed at which the tinfoil clad cylinder moved (or rather rotated). It would till the 1880s develop to a wax cylinder, which was easier to inscribe and reproduce from. One such machine was used by Carl Orff.
The first Gramophone came in 1889, mainly altering the shape of the recording medium from cylinders to the well-known shape of vinyl records but made from hard plastics and shellac. Around 1901, a 12-inch gramophone disk held only a 4 minutes track, speaking volumes about the problems of encoding the complex patterns of sound onto a disk. At the same time, an Edison Amberol Cylinder held 4 minutes 30 seconds but would spin at 160 rpm. Soon after, celluloid would become the recording medium of its time, and the disk the de-facto "standard" as it was much better storable.
In 1925 finally, a real standard was developed to record at around $78^{+0.26}_{-0.08}$ rpm, which lead to only a 0.34 rpm difference between areas of 60 or 50 Hz mains voltage (though they needed different encoder rings), making records interchangeable between both machine types. All these recordings were encoded naturally: the vibrations of the membrane in the recording tool would be 1:1 transmitted to the vibrating stylus that would then do the encoding in such a way that a machine would reproduce what the recording one "heard" quite accurately.
When Vinyl came to the playing field as a recording medium at the end of world war II, so came a swap in the reading needle type: instead of a needle that would agitate a membrane directily, sapphire needles that would agitate an electrical pickup which in turn would activate a speaker. But while the recording technology advanced, the track length of a 12-inch disk was still limited to about 4 minutes at 78 rpm. It would only reach more than this in the last years of its use by applying LP technologies to pack the track tighter in the 1950s, achieving 17 minutes.
1948 came the LP, what we know as a classic vinyl record. At its introduction it could cram 23 minutes onto one side, making this possible by only using 33.5 rpm as the recording speed and thinner, much tighter coiled groves, increasing the information density by a factor of 5.75 for a 12-inch disk. 7-inch 45 rpm "singles" came out 4 years later. Within 10 years, the 33.5 and 45 rpm encoded variants had almost completely replaced the 78 rpm market.
Vinyl
As the history of analogous recordings shows, encoding a sound signal is rather easy in theory, hard in practice. A typical 12-inch LP Vinyl record of 20 minutes is a grove that is  427 meters long and coiled up 667 times. That means a single groove is between 0.04 and 0.08 mm wide - with an equally thin wall between. That means, that to achieve a printed phonograph record, you'd have to print accurately down to 40 microns to get an empty track. However, we also need to add the signal atop. And here comes the real problem:
An empty track has some 22 µm deviations, which the needle will usually not pick up at all. Dust, which creates the crackling at times, is in the same area (1-100 µm). The actual sound signal is encoded to have features as small as 75 nanometers. That is 3 magnitudes lower than the mere geometry of the grove, and equally much lower than any printer - including SLS - can achieve today, as 50 µm is often considered a lower limit in 2019.
To show how much tiny defects would ruin the sound quality, look at this rapid cast of a vinyl record. The resolution of the negative and the subsequently cast record is good enough to recognize the music, but the resin cast did contain so many gas bubbles that the noise level of the copy is very high.
Bonus: Unlike on cylinders the encoding of the signal on disks changes from the start to the end! The vinyl spins at a constant rate, but the radius from the center changes, leading in the speed on any part of the grove to be different as $|v|=|\omega \vec r \sin(\theta)|$, where omega is the speed in rad per second, theta is the angle of the reeding, so in this case, the sinus term becomes 1 and vanishes. This factor has to be taken into account for encoding so the pitch of the record doesn't change if the record is not created naturally by inscribing the signal onto a spinning disk.
Other encoding
Rumble Strips
However, it is quite easy to create a structure that creates sounds based on interaction with another body. Highway Sound Strips create sounds as the car tire bumps up and down, turning the car and tires into resonance bodies while the street "beats" upon it. In the case of a large percussion instrument like a car, we are talking centimeter scale.
Peg-Cylinder
A very simple method would be to go back to encoding and check out the note notation but limiting the length of notes to one unit. Encoding music this way results in pegs or ridges on a cylinder, which then can be used to actuate a mechanism to decode the music and create sounds like in a music box. In a music box of this kind, the demand for accuracy is about 3 to 5 magnitudes lower than in vinyl records: we speak about a tenth of a millimeter to centimeter scale.
Such a Musical box or noisemaker can be easily printed and is pretty much a rumble strip coiled around a cylinder. The length of the sample is determined by the resolution, playback speed and diameter of the cylinder while the complexity is determined by the rows of pegs of it: a noisemaker is pretty much a 1-note, high speed, music box. Typically, one rotation stores about 25 to 30 seconds. Typical examples would be the first part of Für Elise,  or the Marble Machine (Between second 30 and 35 the encoding wheel rotates 1 fifth). Some barrel organs also use the peg method, like one can see here. With some trickery, one cylinder could be used to encode multiple parts that play one after another once a rotation is done by and silencing some parts of the machine depending on an extra encoder, like this 3-part Für Elise music box.

Hole-Plate(-strip)
A different method would be to encode the music as holes in a continuous strip and use air as a decoding method. If the air then gets directed into pipes, we have a street organ. Typically, one would use a paper strip as the encoded message, but it could be printed just as well, especially if one uses a setup that uses plates hinged to one another instead of a rolled-up paper as in this example. With such a way to stash away the extra length, the upper limit for music length rises from a couple of seconds to several minutes easily even with such a "bad" encoding.


Practical concerns smoothing PLA print with chloroform vapours

This Reddit post seems to have some good trial and error dialog.

This Thingiverse post, along with many other references online, suggest that the results are very similar to that of an Acetone treatment with ABS. I'm not familiar with the inner workings of how it works, but the general advice is to be conscious of what you're working with. A heat-induced vapor treatment seems to yield the best surface finish, but can be tricky to track down proper exposure times. It seems that the time required to achieve a desirable surface finish depends on the size and openness of the features on the object. By openness, I mean how evenly the vapor is able attach itself to the surface of the object as compared to other features. Some this variability may be reduced by streamlining the process. Perhaps if you found a way to rotate either the part or the vapor container during the process. This could ensure contact is made in small corners/features. Other variables to consider may be:

If a gradual reduction of exposure is necessary (as is with most heat treatment operations);
How much temperature effects time. Most pages I've read mention 100C as the temp to vaporize the chemical;
Size of the "vaporization chamber" in accordance with how much of the chemical is available. I've used a gallon paint can lined with lightly dabbed paper towel with Acetone for part between 1"^3 to about 4"^3.

That's all I can think of, currently, that could potentially have the most impact on the process. Just as with 3D printing, there's not an easy way to definitively know how your parts will turn out. The sheer difference in the shape of your parts could throw out any "proven process" you come up with. Hopefully this gives you an idea of what things to look out for in starting out.

Here's information about safety, before OP added disclaimer
As with any chemical, always refer to the MSDS (Material Safety Data Sheet)! Whichever supplier you acquire the chloroform from, should ship an MSDS with the product. If one is not shipped, you should be able to request one. If they don't have one, don't use the product and don't purchase from them.

In most cases, you can get away with finding any MSDS online, but I'd recommend trying to get one directly from your supplier as they might theoretically have a different "strand" of the chemical. Therefore, reactions and safety precautions may be different than what you will find online.

A quick search yields this MSDS which states that chloroform does have "carcinogenic effects" along with some other long-term, undesirable effects. As with any other MSDS it continues to go over best-practices and extremity limits.


Always keep printer hot and ready to print

Just set values in your end code for your slicer.  Set the bed to the temp you use, set the nozzle to roughly the Tg temp of the filament you use.  Typically the bed heatup time is the worst offender here.  I wouldn't keep the nozzle at extruding temps, though.


You are probably right, I have a Tarantula as well, and this happened many times to me. The reason is mostly because the hotend fan gets too hot, stops working, then, the filament in the aluminium heat sink melts and sticks the filament inside the PTFE tube. Then, on the retraction, the PTFE is pulled into the gears just like on your picture. Also, the filament stops getting extruded a few moments later.

One solution for that was to buy a new PTFE tube with a pneumatic connector that doesn't allow it to slide into the gears. However, the diameter of the screw thread (of the one that I bought) was too large, so I had to design a new static block for the extruder to fit it.

I chose this type of 1mm PTFE teflon tubing from aliexpress for my replacement.

Maybe you can find a pneumatic connector with the proper diameter.

However the real solution is to check why the heat sink is getting too hot. I bought a few other fans and printed an additional support for them on the hotend and I am making sure the fan stays on all the time.

I hope it helps!


Problems with feeding the filament into the bowden tube

What you are after is a small common mod called... filament guide (as your question title!).

The first one to pop up in my google search was this one: https://www.thingiverse.com/make:346736 which in turn is a make of this model: https://www.thingiverse.com/thing:2242903

Also, a couple of tricks that help on my printers (YMMV):

manually straighten the first few cm filament before inserting it into the extruder (e.g.: remove the natural bend that is there because the filament came off a round spool by bending it in the opposite direction)
when the filament is past the gears/cogs, while still keeping the cogs "open" (i.e.: not yet clamping the filament), twist/roll the filament between your finger.
sharpen the tip of your filament with a pencil sharpener.  This make so that the tip of it is at the very centre of the hole, rather than at its edge.


How can I remove my print from the bed safely

One method that works at our makerspace and also has worked for a user on another 3d printing forum is to use a 50:50 mix of water and denatured alcohol. While the print bed is warm, apply some to the perimeter of the print at the bed surface. Allow it to cool, try to remove the print. If it does not work, reheat the bed and repeat until you are able to release it.


How to smooth the surface of parts printed with Co-polyester (PET) filament

I've found a chart which covers several plastics and solvents and only two of them (Chloromethane and Chloroform) are rated "D" which includes dissolving the material and both seem to be quite nasty and I doubt you will be able to purchase them without being placed on several lists.

Is it possible that something like XTC-3D from Smooth-On would work for you?

Also some more information on dissolving PET here, several sources also mention PET is affected by Hydrogen Peroxide but they do not mention to what degree the plastic is affected.


Wiring Z-stop directly to hot end and aluminum bed / spacers

Aluminium is conductive, but aluminium oxide is not, which is just so what there (unavoidably, since aluminium rapidly oxidises in air) happens to be a thin layer of on top of your bed. The coating is very thin, but it might foul your plans. It would work better with a sharp probe (that can puncture the layer) than with a 3D printer nozzle. You should be careful, because your probing method might be unreliable (which could cause the nozzle to crash into the bed).

Wiring the endstop 5V directly to ground will create a short circuit which will damage your printer. You should use the third (signal) pin and ground instead.


Which connector should I use between the power supply and the Einsy board?

The YL connectors are rated for wires as small as AWG 26 (and as big as AWG 16). If the power panic wires are smaller than this (or the power supply wires larger) you will need to use a different connector for them. Otherwise, I do not see a problem with mixing different wire gauges in the same connector.


For anyone having the same issue I found out it was due to a Z axis motor lock up because the pulley attached to it would get stuck under the bed. I found out because I tried to print again and it locked up completely and I had to pull it out with pliers. Just finished an 18 hour print to confirm


Why is my filament pressed together at the nozzle

As per attached picture I can see that the issue source could be:

the ptf tube is not inserted to the end of heat-break, or it is not straight-cut at the end - see this video for help
the cooler on the hotend is not working properly/not installed and heat goes up to the throttle and melts the material
an object in the nozzle that blocks the flow (usually a ptf tube particle that probably melted) - clean/replace the nozzle


Is the Prometheus system compatible with Wanhao Duplicator i3 Plus?

The Prometheus system is pretty much a Y-coupler and two extruders. So, you need your Wanhao Duplicator i3 Plus to have the connection points for two extruders and the axis, which means you need one free, 4 wire connection slot from a stepper driver. So, let's look what kind of board is in there...

This Melzi Hypbrid is the mainboard the Duplicator uses, similar to a lot of other Melzi derivates (itself as it seems a Sanguino Derivate). The green 4-pin terminal is the extruder. There is only one of these. So it is not useable with Prometheus. You would need to get a mainboard that is able to run dual extruders.


Adhesion problem (heat bed or extruder issue)

If the first layer is not sticking well to the bed it can be caused by several issues. Usually the height of the first layer plays a significant role as does the flatness of the bed. Temperature can definitely  also play a role; you want the temperature to be close or at the glass transition temperature of the plastic filament when it is in a sort of fluid state.

Personally I hated the original tape that came with the bed or blue tape I bought separately. Also the surface finish is nowhere close to printing directly onto the Aluminium bed or on a glass plate. For adhesion, a PVA based spray (e.g. hairspray, or more expensive special print spray like 3DLAC or even a glue stick), should be used as it becomes very sticky at elevated temperatures.

The tape can be removed, but should be replaced with something that grips onto the filament, see previous paragraph. I removed the tape after day one I got build my kit and started printing directly onto the Aluminium bed using the sticky spray.

To answer your questions, the following checklist determines the order in which you should solve your issue:

First check the nozzle position relative to the bed; this should ideally be the thickness of a single plain A4 paper.
Make sure the bed is level; what is meant that the bed is relatively level with respect to the nozzle, not water bubble level with respect to the Earth (you'd be amazed to find how many people do that).
Use the correct bed temperature; it is usually found on the tag of the spool of filament. Alternatively, look it up on the internet, or increase it at first with about 5 degrees Celsius at a time.
You could over-extrude a little for the first layer by increasing the extrusion multiplier for the first layer, or add some extra temperature to the extruder (increase with 5 degrees Celsius).
Printing brims or adding mouse ears or discs integrated in your design may also work to create more grip.

And yes you should remove the masking tape before you put the glass on as it would only act as an insulator.


Z-axis endstop not functioning after Marlin Firmware installation

After gaining more of an understanding of how Marlin works, I decided to look through the  the pins file for the motherboard I am using "pins_ULTIMAIN_2.h".  Sure enough, It had a the wrong pin number for the z stop specified. After changing that number, I gained full functionality.

This is what they should be:

#define X_STOP_PIN         22
#define Y_STOP_PIN         26
#define Z_STOP_PIN         29


Looking for this stl design for a cellphone clamp

This file simply is not on Thingiverse. Not all files are on Thingiverse.
A Google reverse-image-search for that picture in all size told me that the image stems from an all3dp article, and they have a reference link to Pinshape as it is presented here:

The file name of the linked picture is universal-phone-tripod-mount-3d-printing-155113.jpg
Taking that as a search term lead me to pinshape model 37196: 3d printed universal phone-tripod mount by jakejake


What is the correct process to make a correct resin casting for jewelry?

Factually, the correct process is to heat up the mold hot enough to evaporate the positive.

In investment casting the process to remove the wax or plastic positive is called the "Dewax" and "Burnout preheating".

The answer to your question depends on the material you use to generate a negative mold of the positive product. E.g. many silicate based materials require up to about 1100 °C to fully burnout all residue before pouring in the liquid metal.


Z Steppers just hum, vibrate and don't move at all

Try connecting Y-motor to your Z ports. If Y-motor will behave like Z-motors, then there's problem with your Z ports, be it hardware or software. I'm not a RAMPS user, but have heard that there is voltage regulator for every motor port. Sounds like your motors may be underpowered.