White blocks on LCD screen after Anet A8 power up

This is a known and documented problem of this printer. I'm afraid your printer board is dead.

If you have white squares on the display like this picture:

  You need to check Anet A8's mainboard - click reset button and check
  the D1 indicator:

  If D1 lights on for a second then went out and the screen is full of white square, try to reconnect screen wire for several times. When
  it's well connected, click the reset button. If still not working, you
  need to replace a screen.
  If the D1 indicator is always off and the screen is full of white square, you need to replace a mainboard.

From the video you posted it can be seen that the D1 LED does not light up, it is off the whole time. Hence the main board is dead.


Ender 3 Extruder First Layer Perfect But Then Starts Clicking Afterwards

Not allowed to comment, so have to answer:

The temperature sensor is a thermally sensitive resistor. Unfortunately, the temperature is near the high limit of that sensor, and the manufacturing tolerances are very significant. That is why a temperature tower is important for each printer, as well as each filament. (I have 4 printers and each requires a different temperature for the same filament. My worst-case is out by 25 degrees! - it's the one I bought second-hand because the original purchaser couldn't get it to work. I could replace the NTC, but it is easier just to have settings to suit that printer.)
Filament does change over time. Lots of theories about why, but the practical response is to tune settings to suit the filament. The alternative is to modify the filament (eg drying, adding oil to surface, etc.), but even with really old filament, I've found adjusting settings (in the slicer, like Cura) to be the most generally workable solution.

Bottom line is to test, adjust settings and repeat until the system achieves the result you need. Treat most recommendations as serving suggestions, so use them as clues (but not rules) for the puzzles presented as 3D printing.


Speeding up the heating of the heated bed

Changing the PSU with one with a higher amperage will not make the bed heat up any faster unless the PSU is underrated for the amperage required and the voltage is dropping as a result of the load. This can be checked by measuring the output voltage with a multimeter (when the PSU is loaded e.g. by a heating heat bed). In this case, the PSU has a marginal higher Amperage than the printer consumes (even has some room for the over-voltage; under the assumption that it is a good working PSU). Increasing the voltage will decrease the heat up time. There is a screw next to the 12 V connectors that can change the output voltage of the PSU. Usually, it is safe to increase the voltage up to 14 V, but that depends on your whole setup (and 14 V is applied to the whole setup, increasing the current for all parts, including your printer controller board, this board must be rated for the 14 V).  Please do check the stability of the voltage during load.
Although it can be done, it is not something I used. What is an extra minute on a print of several hours?
You can do the math: say the heat bed has a resistance of 1.2 Ω. We only need two formulas:

$U=R\times I$ - potential Difference U is Resistance R times Current I
$P=U\times I=I^2\times R=\frac {U^2} R$. The power P of an item the potential difference times the current through the item.

at 12 V that will draw 10 Amps (12 V / 1.2 Ω) resulting in a 120 Watt bed: $P= 12^2 \text V \times 10^2 \text A= {10^2 \text A}\times {1.2\ \Omega}=\frac{12^2 \text V} {1.2\ \Omega} $),
at 14 V that same bed will draw 11.7 Amps (14 V / 1.2 Ω) resulting in a 163.3 Watt bed.

Use at your own risk!
What you could do to decrease time to heat the bed without changing the PSU or the voltage is to insulate the bottom of the heat bed with heat bed cotton sheets or cork (placemats from IKEA ;) ), put a sheet of cork onto the heat bed before printing and start heating the bed through the LCD panel of the printer or any attached printer controller programs over USB prior to printing.


Overhanging section of part turns into spaghetti

Unsupported parts need to be printed with support. If your supports are too hard to remove, try the Tree Support setting and make sure that your support structure is set up with a gap to the actual print. As we don't know which slier you use, I can't go into more details here.


This may be a result of an unlevel build plate (OP did not specify if calibration was done at time of writing).

If the area that is overlapping is higher (closer to the nozzle), the filament will be pushed down and around the nozzle as it extrudes in that area. This will result in excess filament overlapping unto other strands on the layer.

Please excuse my lack of artistic skills in paint, but the image below should illustrate what can happen when your build plate is unlevel:

Basically what it's trying to illustrate is that if the nozzle is closer than the expected layer height, the machine will continue to flow as if the nozzle is layer height away. This typically results in a larger layer width because the nozzle is essentially pushing material out of the way.

You will notice that as you go further to the right in the drawing, that your layer may begin to "thin out" because if the nozzle more than a layer height away, the filament "stretches" until it settles on the build plate, resulting in a thinner layer width.

Ideally, your nozzle will be parallel to your build plate at all points along the build space and the "Standoff Distance" will be equal to your layer height. So, you should see the top of your bead of filament at the same height as the bottom of your nozzle.


What are the pros and cons of Painters tape?

Read First

Painters Tape does lift the print surface upwards by its thickness. This has to be accounted for in leveling the bed. Different Brands do have different thicknesses and thus need different leveling!
Easy-peel tapes need to be avoided as they don't stick to the surface!

Pro

Painters tape is cheap and easily available.
Laying down a painters tape without overlap is easy.
It is one of the best print surfaces for unheated printers.

Cons

Painter Tape needs to be refreshed regularly.
Weak glue on a painters tape might come off the bed.
Rough-textured tape might stick to the print too good to be easily removed.
Some tapes do leave coloration on the prints.
Cheap painter tapes can be hit-and-miss.
Heating painters tape degrades the glue on it, leading to adhesion failure and staining the actual print surface with residue. It is not advised to use it with heated beds.


This is a so-called MK10 nozzle, it is larger than the normal nozzles you find (as you found out).

There are quite a few questions on this nozzle, with e.g. this answer or this answer.

This nozzle uses M7 (metric threads of 7 mm) to have more room to fit the PTFE tube (white tube) in the nozzle itself. This tube forms the barrier between the heating source and the filament feed so that it does not melt too soon. You can find these nozzles on those typical auction websites by searching for "MK10 and M7".

When you have ordered the correct nozzle you could reuse the existing PTFE liner if it has not degraded or damaged, or buy replacement PTFE tube of 4 mm outer diameter and 1.9 or 2 mm inner diameter and cut a similar sized replacement liner.


The biggest effect I've see on resolution is due to plastic stress due to thermal gradients.

The higher resolution prints build up more layers of material, and each layer has a cumulative effect on thermal stress.  The upper layers pulling up more as they cool, and the lower layers curling up more strongly as the layer count is increased.

To counteract this, a heated (or even just a draft free) enclosure makes a big difference.  Having a heated print bed helps significantly, as long as the bed itself resists deformation (a sheet metal or PCB bed will bend more than glass under the same tension, for instance).

The actual plastic strength, however, appears increased.  Laying down thinner layers of material appears to increase the bond strength between layers.


These skirts they don't contribute at all to help your product adhere better to the build plate other than priming your nozzle so that it is ready to lay down filament for your product.

A skirt does give a good indication of the adhesion prior to printing your product, if the skirt does not adhere, maybe it is a good time to stop the print and re-slice with different options or fix the bed level.


My print did not turn out as I expected. Where can I start troubleshooting?

first issue

bed inclination. it has to be heavy issue :)

if you have any other printouts then please reveal them so we could see if it's the problem

next issue

inversion of hole into solid object

i would say it's caused by wrong calculation of normal vector to some face(s)

algorithm uses normal to calculates what is "inside" and what is not

it's hard to say if it's an issue of

object itself
application in which you modify it (even if duplicating or joining with other objects)
slicer engine

to fix the issue, you can try edit your object (recreate this hole)

but first - definitelly i'd align your bed properly ;)

EDIT

after closer look i bet it's the issue of bad object. it looks like pointed line is kinda remnant of some operations made on object in the past

in other words - it's possible place where normals are reverted and doesn't "create" inside but outside

all above this line is reverted. part of body disappeared and part of hole appeared

this is the issue for sure!


Consider to construct an object of any suitable shape that will properly align with the edge of "A."

The attached image is certainly an odd-shaped object (from a previous test project).

Add a regular/symmetrical object such as a cube and size it appropriately for your purpose. It would not have to be a cube, although such a shape provides for convenient alignment in this case:

Use the alignment tools feature in Tinkercad to align the desired edge(s). In this case, alignment is common right side, centered top to bottom.

After clicking on the alignment button, lower right corner:

Group the two objects using the Group feature.

I created a sample alignment reference in this image and placed it in contact with the group.

Move the group or reference item the desired distance:

Select the group and ungroup it.
Select the initial alignment item and delete it.

Objective completed.


How to solve Ender 5+ weird Z-axis behavior issue?

Ok. So I solve the issue by myself. So to explain the problem a bit further: I had to install a new firmware. That completely reinitialize the z-axis, making the bed goes to the maximum of the screw to the point it lift the print head when I clicked on the Leveling button. To reverse the initialization of the z-axis, I click on the Leveling button,  manually lower the bed by clicking on the upper arrow, then, click on manual or auto leveling, then click again on leveling and start over. At each iteration, the starting point of the bed gets lower and lower to a normal position. I had to do 4 or 5 iterations until I get the desired result. Bonus point: when you click on the move button, the bed goes down if you click down of the z-axis. The opposite behavior is happening in the leveling menu: so you need to click a couple of time (between 10 and 20 time for me at the first iteration) before the bed isn't in contact of the print head.


It might be this board, MakerBot 5th Generation motherboard, (original image)

The image was very small, so it is rather blurry, I'm afraid.

I have contacted the suppliers for confirmation, and will update this answer, when/if I get a reply.

However, according to this eBay item, Makerbot Replicator Motherboard Carriage, it could be inferred1 that the same motherboard (MP6292) is used in the Fifth Generation and the Replicator+

  This part is the aluminum carriage that attaches the main board to the
  printer frame.

  Compatible with Makerbot Replicator Fifth Generation (5th Gen) and
  Replicator+ (Plus).

  NOTE: Motherboard show here is for illustration purposes only!
  Motherboard (MP6292) is NOT included.

  Main board presses right onto the carriage. No special tools are
  needed for assembly. Retaining screw is included.

A much clearer shot of the MP6292 Motherboard

1 However, that depends on whether you want to trust eBay descriptions.


How important is the dimensional accuracy of filament relative to the detail of a print?

Dimensional accuracy is not as important as dimensional uniformity. I can print with undersized (or oversized) filament, adjusting the flow appropriately, provided the filament has a consistent diameter. When creating filament in-house, without expensive equipment, it is difficult to maintain the same diameter throughout the entire extrusion. It is likely this extrusion diameter (when creating filament, rather than the output of the actual print head) to which Barafu is referring when he mentions his tolerances: +/- 0.05 mm in diameter. Which is reasonable.

The "miniature printing" comment likely refers to printing miniature models for tabletop gaming.

If the source filament becomes wider than expected, the output will have overflow, or more material than desired will be deposited, and this will certainly affect the quality of the piece.


Is it possible to 3D print a front bumper grille for a Honda Accord CL7?

Your best bet for the material would be one of the high temperature filaments like the ColorFabb HT ones, they can take quite a punch when it comes to heat.

As for the model, you could try to source one of the grills that is at least as good in shape as possible and get it scanned, there are people offering this as a service for example over at 3dhubs.com

Glue is really depending on the part, I would suggest creating a click-together type of system so the "glue" is only stabilizing it and not beeing a structural component. You can also get hold of a 3D Pen and weld the parts together with the same material used to print.


You just need some wires, nothing special about them. You can use any wire that's flexible enough. For the endstop you'll need 2 wires, for the servo (if you need to extend the cable) 3. The connectors on the end are known as dupont connectors.


SKR 1.4 Turbo - Withhout SD-card reader, bricked?

You may get lucky flashing firmware with the STM Cube Programmer, though I haven't tried that.
The schematic for the SKR 1.4 Turbo shows that the relevant pins for the SD card are also accessible via the 2x3 SPI header - except for the P0.27 pin used for "SD DETECT", which you may have to circumvent.
I believe you should be able to use an "SDRamps" module and connect that to the SPI header via jumper cables.


Prusa I3 starting print above heating bed?

Try setting your "First Layer Height" to 0. This should resolve the issue and will make homing your Z axis a bit easier.


Prusa i3 PLA fails to stick to first layer on curves

It could very well be that your print speed is too high (starting from the 2nd layer) for the motors to keep up comfortably. Try reducing the print speed to perhaps 75-80% of what you are using to see if it addresses the issue. You should also check you model to make sure there are errors in the STL. Sometimes such mesh errors can cause funny things to happen. Do you see the irregularities in the print preview at all?


What is causing the walls of my prints to separate?

I have faced the same issue if it concerns just gaps between the walls (to the point you could put a nail in between the outer and inner perimeters, so clearly the perimeters were not bonding), for me this was fixed with proper tension of the belts of my Prusa i3 clone, and for my other (CoreXY) printer reducing the friction of the X-Y system. Both help position the head better for proper wall adhesion.

Now that you have posted a picture of your product I do not think the above is applicable to you. Your print looks as if it has an under-extrusion problem as the lines on the faces are clearly not touching, you see the diagonals of the layers beneath. This under-extrusion also may contribute to the vertical wall bonding problems you mention. To fight under-extrusion you need to check a few things:

Be sure the slicer has the actual filament diameter as mentioned on the box, or measured at various points (if it varies, take the mean value).
Check your extruder setup to see whether you have play or friction preventing filament to extrude freely.
Also check whether your extruder gear is not loose, re-tighten the grub screw.
Final step is calibration. You want to be certain that when you demand 100 mm of filament to extrude, you actually extrude 100 mm. Put a mark on the filament and extrude 100 mm using a tool like Pronterface or Repetier-host. If this is off you should readjust the steps per mm in the firmware (if you are able to do so), or increase the extrusion multiplier or flow in your slicer.

Please look here or here for more information.


I found step-by-step instructions on Instructables specific to 3D-printed parts. In summary:

Sand and brush with acetone for a smooth finish (I guess the acetone vapour treatment would work as well.)
Prime with plastic primer
Spray-paint with a satin, nutmeg-coloured base coat
Add grain with darker, acrylic paint using a fine brush


That are certainly trade-offs between the two options.

I think main trade-off between the two options you described would be visual details vs. configurability.

With a scanned design you have the ability to capture all the visual details that are in your hand crafted model.  Those same details might require more effort than you are willing to put into a CAD design (like window and door detail and other architectural accents).

The big disadvantage of a scanned model it that it would not be parametric so you can't fiddle with design details - like adjusting the width or spacing of the windows, the position of a door or external approach (stairs, etc).  Also you could play with the external skins/finishes and play with how wood looked as compared to concrete of brick.

Another advantage of a CAD model would be that you would not be able to break out components and print them separately because of print volume issues or to be able to print in different colors.

My personal preference would be to create a 3D Model using a CAD package.  The limitation on this would be that it might not have the same level of detail; but it would be much more flexible.  You could probably create the base design pretty easily either from the architectural drawings or by deconstructing the hand crafted model.  The model was probably built from pieces much the same way a 3D CAD model is created.

Here is a good example of how to do that.  In the example, they create a pretty detailed house design in Sketchup in 35 min by starting with scans of the architectural drawings.

There are quite a few other similar videos so you should look for the one that fits you best.


How to use second hotend for bed heating?

Although it appears to be a RAMPS compatible board as described in this now deleted answer, it is not using a RAMPS pin configuration.

To fix this in the firmware, this requires an upload of newly configured firmware to the board. See e.g. question: "How to upload firmware to reprap printer?". For Marlin firmware (which is also loaded at the factory) You need to assign the correct board number or constant name (amongst several other things) in the Configuration.h file. Note that this is "clearly" described by the manufacturer here.

From factory, a version of 1.1.X is loaded note that version 1.1.9 is the last of the 1.x branch, the default is now version 2.x.

From the manufacturer of your board you find that:

#define MOTHERBOARD 7

needs to be set. Note that using number is old, nowadays you would use a constant. For board number 7 this is the constant defined as BOARD_ULTIMAKER. Note that in version 2.x this number is now 1117, so the preferred usage is the constant name BOARD_ULTIMAKER!

Specifically for your board, the Configuration.h file should contain:

#ifndef MOTHERBOARD
  #define MOTHERBOARD BOARD_ULTIMAKER
#endif

The pin arrangement used by this board is found in pins_ULTIMAKER.h.

In this pin file you need to swap the pin numbers that identify the bed and the second extruder (E1) thermistor pin. In this file change:

//
// Heaters / Fans
//
#define HEATER_0_PIN        2
#define HEATER_1_PIN        3
#define HEATER_BED_PIN      4

to:

//
// Heaters / Fans
//
#define HEATER_0_PIN        2
#define HEATER_1_PIN        4 // or -1
#define HEATER_BED_PIN      3

Note that it could be that the E1 heater output may not be designed to take the high current load the bed requires (depends on the traces on the board and the used MOSFET; with respect to the MOSFET, the manufacturer states that:

  3 55Amp MOSFET (with LED indicator, the actual output is restricted by the PCB board and the connector), all 3 MOSFET are equipped with heat sink to ensure sufficient heat dissipation and stable operation

, implying that the MOSFETs are identical). It is therefore advised to use an external MOSFET module. This will keep the high currents away from your printer board. Such a module looks like:

You need to wire the second extruder heater leads to the white cable, the power and the bed leads use screw terminals and are clearly labeled.


Knotted String as Replacement for Toothed Belt

I’m going to recommend not using a fishing line with knots.  Probably the biggest problem you’ll have using the fishing line with knots is if the knots are not perfectly spaced,  movement along the X or Y axis is not going to be consistent. This could result in weird deformations in your print.

Depending on how you tie the knots they may not grip the teeth of the gears quite well enough to prevent slippage.

Both of these issues will mean that you will not get very good quality prints assuming the print doesn’t outright fail.

You would be better off waiting to get the correct belt then attempting to use fishing line.


Your hotend temperature is too high and/or too less part cooling. The part cooling is very important to solidify the hot fluid filament in time to have a solid fundament for the next layer. PLA has a reasonably low glass temperature (at this point the filament is weak and mealable/flexible, at about 60 °C), if the part is not cooled properly, the part temperature can be over the glass temperature when printing the next layer and will distort the previous and current layer.

I print PLA at a maximum temperature of 200 °C (for my thermistor reading).

A combination or a single of these parameters not being the correct value will cause the dent at the front and the stringing and letters to be faded as the filament is not cooled properly and deforms the previous and current layer, this easily shows up in overhangs like at the bow of your print.

Try to lower the hotend temperature by 5 °C per next calibration print (or start at 200 °C and work down from there) and increase the part cooling a little if possible (35 % to 50 %). The build plate generally does not need to be 5 °C higher for the first layer nor do you need an extra 5 °C for the hotend, PLA is not that difficult to print.


Prusa I3x and repetier host heat problems

You may set the temp in Repetier but when you run the gcode it will send any of the temp settings in the file. So you may set 210 °C first but if 200 °C is in the G-code the printer will take that (as the gcode is sent one instruction at a time). However I also noticed that after the automatic bed leveling any manual settings on the printer are reset to the G-code (I assume the file is re-stating the temp after bed leveling) So I have to override the file temp after the bed leveling is complete.
I now use OctoPrint and it has a cool feature : temp offsetting, you can specify an offset for every temperature the OctoPrint server sends to printer; e.g. in your file it is set to bed: 110 °C and extruder: 230 °C you can tell OctoPrint to take 20 °C off all bed temps sent and 45 °C off any extruder tempperatures sent. It's great for tweaking the temperatures of your G-code without editing or re slicing, just change the temperature offset and reprint.
I noticed on a previous firmware version for the I3 mk2s Repetier did not connect properly to the printer this problem disappeared in the latest Prusa firmware (v3.1).  One of the symptoms I noticed was the temperature settings were not taken by the printer.
Some slicers have a setting to have sticky parameters, i.e. set temperature once don't bother re-sending. However if this was turned off, it is possible that the generated G-code repeatedly send the temperature settings with every instruction, continuously resetting and overriding these values. (OctoPrint temperature offsets would correct this)


How can I set the 1st layer after a raft in Slic3r to print at 1st layer speed

This is still work in progress, and here is what I have so far, but first:

A useful alternative for similar problems:

A problem very similar to this would be to use different settings for different parts of a model in Slic3r. For most settings, this can be achieved through modifier meshes.

Post processing scripts:

As far as I know, Slic3r does not give you the option of setting the speed of the first layer after a raft directly, but they do allow you to run post processing scripts; that is, to automatically run a set of operations - programmed by you - on the g-code output.

Although far from trivial, you can in theory make a program that runs through the output g-code, adjusts the settings to your preference, and then saves it again at the target destination.

Tuning overall printer speed through g-code:

As it turns out, there is a simple g-code command that sets the overall speed of your printer's operation:

M220 S[some number]     ; see the link above for compatible firmware

A newsletter from Reprapwold explains that:

  For example M220 S50 will reduce the speed to 50%
  of the original sliced G-code. If you want to hurry your print to the finish in time
  for dinner, use M220 S200, to print twice as fast (200%)

In other words, just like some printers allow you the change speed mid-print, you can use the M220 command to override the current speed used, either through a user interface such as PrintRun, or by fiddling with the original g-code itself.

Manipulating the g-code output to adjust speed settings:

The easiest way to achieve our goal would be to manually manipulate the output g-code file through a text editor, and insert our M220 command in appropriate places:

Set M220 S50 just before the first perimeter layer (after the raft's interface layer), to slow down the first layer of the actual model.
Set M220 S100 sometime after the first perimeter layer, to resume the normal speed settings.

In order to do this, though, we need to be able to distinguish these two points in the g-code output.

Distinguishing insertion points:

Slic3r offers a setting under Print Settings -> Output options -> Verbose G-code that - when enabled - inserts written comments all throughout the g-code files generated.

If one inspects a g-code file outputted for a model with raft, one will find the comment:

; move to first perimeter point      <- lets call this A

and

; move to next layer (x)             <- lets call this B

littered several places throughout the gcode.

It is under my impression that the first occurrence of comment A happens right after the raft is finished, and before the actual model is being printed, while the first occurrence of comment B succeeding comment A can be used to set the speed back to normal.

It should be noted, however, that the comments in the output g-code does not seem fully consistent, and I would therefore not recommend anyone to automate this logic into a script without possibly finding other, more reliable breakpoints, and thoroughly verify these through several different models.

I have not looked into the details of writing an automatic script for this task as of yet.


Thermister stops reading temp after a few seconds. (Marlin 1.1.8, Tronxy X5s stock Melzi board)

Thermal expansion is opening a connection somewhere. It might not be one of your solderings, but if you shorted the board bad enough to fry pins, it could have cooked something somewhere else, and putting current through it is heating up the spot enough to break the connection. Either somewhere else in/on the board, or inside of the IC chip itself.


Thank you all for your suggestions and help.

It appears that I was just running the printer too fast and slowing it down to about 10% of my original speed "fixed" my problem.
I don't know where i got the rediculous speed from, but 1200 mm/min is WAY too fast.
More like 150 to maybe 200 mm/min is what it should have been.

Oh well.. comes under the heading "pay attention" I guess!


Found the cause of the gaps. it was one or both of the following:: he x-carraige belt was rather loose; I think I'd overtightened the x-carriage assembly with the print head on it and the motion had a couple of places where it was a tad tight. Adjusted both these things and all the problems went away. What's especially interesting is that I'm now getting better quality prints than I've ever had. It looks like it is worth checking the tightness of everything on a new Ender 3 Pro to ensure it is all as it should be!


How can we control the airflow in a fan which can be 3D printed?

Look at your fan: it spins in one direction, and the blades push the air from one air to the other side. In fact, the fan is nothing but a propeller! There are ways to optimize them. The Rotation goes for example clockwise, the leading edge grabs the air and the trailing edge releases it on the other side, and if the leading edge is towards you, then the air is pushed away. In the simplest way, it would suffice to physically flip the fan around.
A 3D printed new fan would need to have the whole geometry of the fan blades "flipped" (mirrored around a non-rotational axis). Now the leading edge of the fan is away from you, the trailing edge on your side, the airstream is again from the leading to the trailing edge, and the air comes out on your side.
cave!
Not all fans can be made to reverse the airflow by flipping the fan geometry: Radial fans just because less efficient.
Other fans can be made spinning backwards by swapping the polarity, but others use a simple diode setup and always spin their way. Also note that fans spinning backwards often suffer from reduced efficiency, as the blade geometry is optimized for one direction of spinning.


Efficient and easy way to thermally insulate the heat block of the hotend?

The "quick and dirty" approach is to just slap a bunch of Kapton tape on there. The more the better! (Until you need to dismantle for maintenance, anyway.)

I find pre-cut ceramic tape + kapton tape "blankets" to be easy and effective. E3Dv6 and Replicator 1/2 style hot blocks should be compatible. Or you can cut your own using a sharp hobby knife.

http://www.fargo3dprinting.com/products/makerbot-replicator-2-ceramic-insulation-tape/

The main downside is that they don't insulate two sides of the hot block. But covering the top and bottom provides much of the practical benefit, and you can always add a few more wraps of Kapton tape to cover up the rest of the surfaces.

Another good option that has recently started to become popular is fiberglass heat shield tape. It has a silicone adhesive, woven fiberglass mat, and shiny aluminum surface. (The reflective surface reduces heat radiation.) It's often used in automotive applications around mufflers and the like. You can cut it up into little rectangles for each side of the hot block, or wrap the block similar to Kapton.

https://shop.raffle.ch/shop/insulation_material/

Main issue is quality -- not all brands have adhesive that will hold up to high temp printing. It may smell when initially "burned in" due to the adhesive cooking a bit. I also find that you need a couple layers to get as much insulation as the ceramic+kapton blanket when there's a lot of airflow around the hot block.


Cura projecting floating print onto build plate during slicing

I've been playing with this and came up with a solution, so I thought I would share in case anyone else had this issue in the future. In Ultimaker Cura I enabled supports and z-hopping before I sliced the part, then I ran this Python function to remove the supports and get the extruder setup.

import re

def float_part(file):
    printString = ';LAYER:'
    partString = ';(.*?).stl'

    with open( file , 'r') as content_file:
        content = content_file.read()

    printArea = re.search( printString , content ).span(0)[0]
    partArea = re.search( partString , content ).span(0)[0]

    uncommentedLine = partArea - re.search( '\n.*?(?<!;)\n' , content[ partArea:printArea:-1 ] ).span(0)[0]

    lastExtrusion = uncommentedLine - re.search( 'E' , content[ uncommentedLine:printArea:-1 ] ).span(0)[0]
    secondLastExtrusion = lastExtrusion - re.search( 'E' , content[ lastExtrusion-1:printArea:-1 ] ).span(0)[0]

    lastExtrusionAmount = float(re.search( '\d+(\.\d+)?', content[lastExtrusion:] ).group(0))
    secondLastExtrusionAmount = float(re.search( '\d+(\.\d+)?', content[secondLastExtrusion:] ).group(0))

    ResetCommand = '\nG92 E' + str(lastExtrusionAmount) + '\n'

    with open( file , 'w') as content_file:
        content_file.write( content[0:printArea] + ResetCommand + content[uncommentedLine:] )


Frightened of Cheap Chinese Power Supply as I hook up the heated bed

A MK2 heatbed will draw around 12A. The motors and hotend draw only very little power (around 2A, 5A peak), so the 30A supply you have has significant headroom (it is often recommended to derate a power supply by 20%, so a 30A supply would be good for 24A - you're still well under that). It should work fine, even given its dubious provenance.

Winter versus summer should not make a big difference. The largest power draw is during the heat up phase. In winter, the bed will use slightly more power to stay warm, but regardless of whether it is summer or winter the peak power draw during heat up will be the same.

The cheapness of these supplies tends to be reflected in more output ripple (but for heating the bed and running the motors you don't need a very stable voltage) and improper filtering. This may inject noise back into the mains, possibly affecting other equipment nearby. Should this occur, you can just stop using the power supply. However, in my experience, they can deliver the rated power just fine. They're not completely horrible.

Your biggest concern should be whether the wires that lead to your heated bed can handle the current and whether the screw terminals are properly tightened. During the first use, you should check that the power supply does not get extremely hot. If it's so hot it's impossible to touch for more than 1-2 seconds you should not use it.


FLSUN QQ doesn't print and stops at Z=15 mm

A distance of 15 mm is about the height of the probe or Z-offset. That can be a clue.

Compare the G-code from the testprint with the G-code you sliced. It can give you other clues.


Minor stringing issue, only happens in helpers & infill areas

If the problem occurs in or immediately following printing of support material, it's probably Cura's Limit Support Retractions option, which defaults to on. This is probably the single worst default Cura has, and it causes all sorts of problems - surface defects, difficult-to-remove support, underextrusion, etc. - due to basically skipping all (necessary!) retractions while printing support.
If the problem occurs in infill area, it's probably Combing. Lowering Max Comb Distance With No Retract to something very low (150-200% of the nozzle width, so like 0.8 mm) should make this problem go away, but at some nontrivial cost to print time. If you make this change, you almost surely need Zig-zaggify Infill enabled if you want to avoid very high cost to print time and excessive retractions.


Do aluminium PCB heatbeds reduce hotspots?

A thermal image of my aluminum heated bed does not show hotspots, although the edges are cooler than the majority of the center.


Cloning the Marlin git repo while keeping my configuration.h settings?

Based on this answer, you need the following procedure:

Stash your local changes using git stash
Pull from remote repository using git pull
Merge your stashed configuration file using git stash pop

Of course, if there are changes in the configuration.h file on the remote repository and cause conflicts, you will need to resolve them, but it should be straight forward.


Ok, so to answer the primary question: What flexible filament will operate consistently at 250°C?
Man... this is a tough one. Some filaments, like PEEK and ULTEM 1010 can operate up in the 200c range.... but they're not flexible at all.
Silicon might be able to work, but you're still pushing boundaries.
Now.... I'm lucky to be in a 3D Printing company.... and we're testing a super-high-temp flexible material, very similar in temperatures to ULTEM. I'll definitely check back and let you know how it goes, but....
Honestly, that's so hot, readily available thermoplastics may not be an option unless you're in Aerospace with an unlimited budget..... which, based on the requirements, would make sense, lol!
I'd say the most readily available way to get this done would be 3D Printing a mold, in which to put your silicone, and bam -- you've got the part.


How to tell if A 3d printing kit has a replaceable nozzle

Prusa has a replacable nozzle. Usually all printer does have an replacable nozzle. Since this is a part of a printer which could get jammed during a printer life.

As written here: https://www.prusaprinters.org/prusa-i3-is-now-1-75-mm/ The Prusa i3 uses an E3D Hotend. This Hotend has many diffenez nozzles. You can search on E**ay for E3D V6 0.1mm nozzle and you will find a lot of offers.


Considering this is an Ender, it is probably caused by the rollers on the X axis or the un-driven right Z post.
I've also seen behavior like this caused by a too constraint PTFE Bowden tube, at the far end the tube pulls on the carriage lifting it slightly upwards, hence a different/larger gap.


Prusa i3 Z axis only goes down (even on up command)

It could be a hardware fault.

First check, and compare, the control board connections to the motors of the three axes. You don't state it in your question but, presumably, the X and Y axes move correctly? If so, then compare the connections for the Z-axis motors with the connections for the motors of the axes that work as expected.

If they are correct then the problem is likely to be with the firmware.

Have you...

homed the Z-axis yet?
installed the endstops?

From X Y Z axis only move one direction?:

  Using Marlin? Before you do a G28 homing the axes will only move
  towards the endstops. But also check your endstops with M119 to make
  sure they are triggered at the right time. On older Marlin, you may
  need to set DISABLE_MAX_ENDSTOPS (on a machine that has no max
  endstops). Newer Marlin uses USE_XMIN_PLUG, etc., to specifically
  set which endstops are connected. If the switches show the opposite
  state (off when triggered) then set the
  [XYZ]_(MIN|MAX)_ENDSTOP_INVERTING flags, as needed.

Likewise, from Building a Prusa I3 3D Printer:

  You will probably also find the motor will turn only in one direction. This is normal for now as we don't have end-stops installed and haven't homed the axis - so the software doesn't know how far it can go in one direction or the other.

As Mark states in his comment, the P802M uses a Melzi board. From Github: Repetier-Firmware/boards/Zonestar P802M/:

  There are some printers sold under different names like 'Zonestar
  P802M', 'Prusa i3 P802M DIY kit', 'Anet A8-B', etc, which have LCD
  20x4 with 5 keys controller connected to Melzi V2.0 board via 10 wires
  cable. Keys are connected to a single analog input using resistive
  divider.


The density of PLA is around 1.25 g/cm³ and the density of PETG is around 1.38 g/cm³. When you're talking about the amount of energy needed to melt a particular volume (which is what your extrusion units are) rather than mass, you need to scale the heat capacities (with units of $\frac{\mathrm J}{\mathrm g\cdot \mathrm K}$) by the density to get $\frac{\mathrm J}{\mathrm{cm}^3\cdot \mathrm K}$. This brings their volumetric heat capacities somewhat closer: 2.25-2.63 vs 1.52-1.79 (about 47% higher for PLA rather than your figure of about 62%), but with PLA still higher.

You also have to account for heat loss to the environment. PLA is typically printed around 200°C or 210°C at most; PETG in my experience requires 250°C to reach low enough viscosity to be printable at any speed. Assuming an ambient 20°C, the rate of heat loss should be something like 25% higher for PETG. So the hotend has that much additional energy needed to begin with.

Beside that, PLA is printed at temperatures where it's still extrudable and able to bond even if the temperature drops significantly below the nominal nozzle temperature (down to 180°C, maybe even slightly lower), whereas PETG has trouble with increased viscosity and poor bonding right away if temperature drops.

Going broader still, PETG seems to need to keep its heat longer after being extruded in order for layers to bond well. (As evidenced by the need to lower fan or turn it off completely.) A slow-moving nozzle both provides heat (from the proximity of the nozzle itself) to slow the cooling, and reduces air flow across the part (by not causing as much air flow itself just by moving).


How to add a proper fillet to corner of a cuboid in Fusion 360?

There are probably many ways to do this, this method describes how I do this.

First you need to fillet the top, then you chamfer the edges.

Create a lid:

Fillet the corner edges:

Chamfer the lid edges:


What else can I use for a 3D Printer frame?

Were I to build a frame now, I might use 1" square steel tubing members, welded together.  You could also use aluminum, but for the same cross-section, the steel will be stronger.  It is also easier to weld.  If welding is not available, you are limited to shapes which can be bolted together.  This is not impossible, but it requires more thoughtful design.

For the guides for moving or sliding elements, stainless steel drill rod is good.  Because it is round, it doesn't constrain rotating motion, so you might need two drill rods, spaced as far apart as your design allows.  The twisting force will be harder to manage with rods than it would be with a solid element.  If the parts are moving during printing, you could consider stainless steel tube or aluminum rod to keep down the weight.

If you have the machining ability, instead of rods you could use a T cross-section (steel or aluminum) with wheels rolling on the two outside elements of the T.  Machine is likely needed to adjust the profile of the edge to more closely match the wheels (which could be /V\ shaped), and to make the separation be accurate enough that you wouldn't need a spring element to clamp to the T.

There are many materials and forms that could work.  You are limited only by your fabrication ability and access to materials.


Building a pivot linkage for servo steering with 3d printed parts.

A correct length shoulder screw would work great in this application.  They have a shoulder that is held to a precise diameter and a length.  You can thread a nut on and tighten it against the shoulder to prevent clamping your pieces.  They may be hard to find locally in stores but are readily available at places like MSC, McMaster-Carr, and Bolt Depot.


Item 1) The holes are not round. Why???

Two things about this. First, the print is upside down. The holes are not round to accommodate the fact you cannot print a round hole unsupported. If you try to print the circle unsupported, when you get to the top portion, it will sag until the print catches up to it. By that time, the circle is flat at the top and you won't be able to fit whatever you were trying to fit into it (without some post processing). Printing the V-ish looking part at the top will ensure you'll be able fit things through it you meant to fit through (sorry if that's redundant). If you'd like to know more, take a look at the following Maker's Muse video:

  Item 2 ) There are some little squares inside the piece which i don't know if they are there for some structural reason

To be very honest with you, I don't know why the little squares are there either, however, I believe you can answer this part for yourself.

I think the answer lies in the part, meaning, if you can manipulate the 3d design in whatever you're using to design it, you can look into the part and see what's going on with it. It appears there are dashed lines in the center parts, which would make me believe these are hidden lines. There is a feature there which is inside of the part which you cannot see otherwise. By turning it, you should be able to decipher what these features are for and therefore should be able to discern what the small squares a for as well. If, after you've looked the part over completely you cannot discern a purpose for the squares, don't design them into your part. It may just be they are an artifact of the design itself and doesn't provide anything worth repeating in your own design. Bottom line, don't get hung up on the minute details which in the end don't mean a thing.


How can I make this rounded enclosure feasible to print?

With a couple of minor adjustments, that would print just fine standing up as it is.

Alternatively you could lay it down with the open side facing upwards and use a few supports (my least favourite method), or simply make a flat spot on the back to lay on the printer bed. Which is probably what I would do.

As far as shell thickness goes - 2.5 mm is pretty heavy duty. You also need to bear in mind that it's best to have a thickness as a factor of the thickness of your bead or your layer height (depends on printing orientation) - assuming you are going to print this yourself. So usually that would either be divisible by the bead width or by the layer height. If you want translucent - easy enough use translucent or clear filament. I'd probably go for 1.2 mm or 1.6 mm wall thickness.

I made an angel at Christmas with clear PLA and quite a thick wall (wasn't my model and I didn't bother measuring - but at least 2 mm) and an LED candle lit it up really well.

It's much easier doing this kind of thing after buying the printer. that way you learn much quicker what works and what doesn't.


How to switch motor outputs and use E1 as X, in Marlin firmware?

When using Marlin firmware you could easily change the pin layout of the extra extruder (E1) with the broken X stepper pins by changing the pins_RAMPS.h file.

Download the firmware and open the firmware project in Arduino IDE. Navigate to the "Steppers" section of the pins_RAMPS.h file and replace:

#define X_STEP_PIN         54
#define X_DIR_PIN          55
#define X_ENABLE_PIN       38
#define X_CS_PIN           53

for:

#define X_STEP_PIN         36
#define X_DIR_PIN          34
#define X_ENABLE_PIN       30
#define X_CS_PIN           44

and also change:

#define E1_STEP_PIN        36
#define E1_DIR_PIN         34
#define E1_ENABLE_PIN      30
#define E1_CS_PIN          44

to:

#define E1_STEP_PIN        54
#define E1_DIR_PIN         55
#define E1_ENABLE_PIN      38
#define E1_CS_PIN          53

When the file is changed an saved, build and upload code to your board and plug the connector of the X stepper into the E1 header.


Zortrax m200 skipping through menu options on it own and live print bed

This sounds really concerning.
Instantly remove the machine from the power and check EVERY wire if it might be broken!
Check if your power supply is properly grounded!
Check if the connectors of the bed are undamaged!


What is the difference between STL and OBJ files and which one should I use?

STL is the de facto standard in consumer-grade 3D printing.  It is a bare-bone format that describes the shape of the object by defining the coordinates of all the vertices of all triangles that a surface may be subdivided into.

This means that in STL any curved surface is represented with an approximation of many very small faces.

OBJ is also somewhat common, but it was originally developed for computer graphics, not manufacturing, and as such is capaple to store information like the texture images to be applied to the surface, which are of no use in the 3D printing world.

In terms of geometry description, OBJ is more capable than STL, as it can describe "real" curves, without the need to approximate them to a series of polygons.  The benefit of this feature is however more theoretic than practical, as:

most entry-level CAD software don't make use of that feature and create a STL-equivalent OBJ file (so, still with polygons)
a typical STL model for 3D printing will have enough resolution to give the illusion of perfect curves (the same way a high-res screen gives the illusion of perfect curves, despite its pixels being arranged in a squared matrix),
the slicer/printer's firmware may themselves approximate an accurate curve to a series of segments

Short said, I would suggest you use STL unless you have a specific reason not to.

If you would find yourself in need to accurately describe curves I would rather use the STEP file format, as that has been specifically created for manufacturing, rather than "borrowed" from computer graphics.


I upgraded to the latest firmware, and now everything works again.


Edit G-code to change print order of multiple one-at-a-time print jobs

You can open the G-code file in any text editor and copy-paste the relevant sections of G-code to reorder them. It will be fairly obvious where one object ends and the next one starts because the printhead will move back down to Z=0; you can do a simple search to find the commands that move to Z=0 (in my version of Cura, it inserts a comment ;LAYER:0 at the start of each object).
To ensure that the extruder starts in the correct position, look back at the previous print (in the original order) to see where the extruder finished, then insert (at the start of the new print) G92 Exx.xx where xx.xx is the previous position of the extruder. If looking back to the previous print is too tedious, you can also just use the very first extruder position in the print itself and use that. It will just skip printing the very first section of brim/skirt, which doesn't make a big difference.


Fixing uplifted magnetic heatbed surface

The Ender 3 Pro bed looks like a sheet of steel with a stick-on plastic sheet.  If the steel plate is bent, you would probably be happier to buy another one.  If the plastic film has lifted off the bed, you might be happier to buy a new plate, although there are sheets of film with adhesive available.

If you are printing small objects, you can plate them other than in the center.

If the problem is that the central bump screws up auto-leveling, try ironing while you are waiting for the new one to arrive.

I looked on the Creality site but did not find listings for spare parts.  You may need to be a customer to see that part of the catalog.

Ironing it might work.  The adhesive is probably good for 110 C.  I say that because the specs for the Prusa3D bed are similar.  I looked up the 3M product used for the PEI surface and found that the adhesive was the limiting factor at 110 C.  The PEI was good for a higher temperature.  If ironing doesn't work, buy another one.  If ironing does, come back and answer your own question so the information is preserved.


The proper answer could be not related to Fusion, as you already noticed.
I suppose the issue is that the Ultrabase surface (or any other glass surface you have installed) was not cleaned during the first month? So it should be cleaned from grease and possibly dust. The general cleaning method is to use isopropyl alcohol (IPA) from time to time (btw. I am curious if it is advised in a printer's manual). If it does not fully help, I suppose using a dish soap with hot water prior to IPA is good step. Though I do not own this bed, so could not be 100 % sure of impact. (Definitely do not use any extra adhesion helpers for Ultrabed, because it has some specific microstructure which will get stuffed.)
You could want review other threads like this How to get Sunlu PLA to adhere to the printing bed? to get other hints and supplement your checklist. One thing to check first (and regularly) is proper bed levelling at current moment - and compare to initial layer settings in Cura (thickness, width, flow percentage).


I believe the little experiment made by E3D - the same link you provide - answers your question very well. Several points about wear can be found in this article. After printing only 250 grams of ColorFabb XT-CF20 (carbon fiber filament):

The nozzle diameter had increased markedly
The inner walls of the orifice (opening) showed deep sharp ridges and grooves
The tip of the nozzle had become critically rounded, and shortened

All of these symptoms were found repeatedly for standard brass nozzles.

In particular, I believe the last of these symptoms may be the one most easily identifiable without accurate measuring equipment (and without observing print quality).

With regards to reduction in print quality, these symptoms could be simulated by:

Setting the nozzle diameter too big in your slicer
Leveling your bed too high (the rounded tip will also reduce the length of the tip)
Printing with a partial clog that interruptus normal filament flow (due to the grooves and ridges)

Exactly what this will look like on your printed part is hard to predict, but I would assume you could see blobs, under-extrusion, poor layer adhesion, as well as an irregular surface finish of your top layers.


How to set up Marlin to use a heated chamber?

Here is what I found to be the easiest solution. Please use this image for reference. I recommend doing these instructions once from source, since a lot of things can go wrong,  then once everything works, go back and integrate them into your existing Marlin codebase.

Get some 5V relays to run the infrared lamps. These relays take in a 5V digital signal from an arduino pin. When the arduino activates these pins, the lamps will turn on. Get a cardboard box, line it with aluminum foil, and attach a lamp to the top of it using a lamp switch. One wire for the lightbulb goes to NO on the relay, the other goes to D-. One wire from 120V power goes to COM, the other also goes to D-. The yellow "jumper" on the relay boards I posted goes between HIGH and the middle pin. These are pins on the relay, not the MKS GEN board.
On the MKS GEN board, we will be using the X-MAX endstop as the digital pin to run the chamber. Wire the 5V pin on X-MAX to the D+ of the relay. Wire the GND pin to D- of the relay with the two other wires there. Wire pin D2 on the MKS GEN Board to IN on the relay. Bold means the pin is on the MKS GEN board.
Clone the Marlin-2.0 repo: git clone -b bugfix-2.0.x https://github.com/MarlinFirmware/Marlin.git
In Configuration.h, change TEMP_SENSOR_CHAMBER to 1 or 11 (depends on your thermistor, might be other values.) Since we will be using the board's second extruder thermistor as the thermistor in this example, change TEMP_SENSOR_1 to 0 for now.

#define TEMP_SENSOR_0 1
#define TEMP_SENSOR_1 0
#define TEMP_SENSOR_2 0
#define TEMP_SENSOR_3 0
#define TEMP_SENSOR_4 0
#define TEMP_SENSOR_5 0
#define TEMP_SENSOR_BED 1
#define TEMP_SENSOR_CHAMBER 1

In the file src/pins/ramps/pins_RAMPS.h, add this line:
#define TEMP_CHAMBER_PIN 15. Note that this is the thermistor
slot usually used for a second extruder. If you're already using
this thermistor for the second extruder and want to use a different
analog pin, see this question. You'll need some resistors.
Also, around line 95 in pins_RAMPS.h, change X_MAX_PIN to use an unused pin. The number 4 is good. If you don't do this, your Chamber's digital Pin will be always "on" by default. You want it off by default, then activated by the Marlin code.
In Configuration_adv.h, change //#define HEATED_CHAMBER_PIN 44 to #define HEATER_CHAMBER_PIN 2 to use the X_MAX endstop's digital pin.
Upload...
Go into OctoPrint settings. Click Axes and Volume. Next to a checkbox for heated bed, there is a checkbox for heated chamber! Click that, and your chamber is active.
If some part is wrong (e.g. lamp doesn't go on because wire came loose on relay), debug that and keep working. Check the octoprint log to make sure the C value is shown.
Once everything works, generalize these solutions to your set-up (e.g. using multiple extruders).


Cura acting REALLY sluggish all of a sudden

Cura has and/or had a memory leak (or some other similar phenomenon) that occurs if you leave it running for a long time.  I have left Cura running for days or a week or three and eventually ran into a similar problem.  One could infer that you've left Cura running for a month, though it's not clear in your question.

I update Cura a few weeks ago (maybe a couple months) and noticed that it had a substantially smaller memory footprint, so that tells me they are working on memory management.

Looking in the release notes, you can see that 2 versions ago they implemented analytics, which is possibly a reason for the poor performance.  You'll also notice a lot of new features and bugs fixed int hat version.  That means a lot of work went into it.  Coupled with the short time to another release, and I think they're working on  fixing things.

For a more precise answer, include details and specs about your PC, internet connection, mother's maiden name, SSN, etc.  I'm kidding about the last 2, but it is probably a PC or software problem that you're running into.


Wrench drops temperature of heater block when tightening nozzle

Mitigating "heat loss"
Technically, we don't lose heat, we have a drain of thermal energy out of the parts, but let's stay simple.
To combat the loss into the holding/steadying wrench, I use a vise: it might lessen the heating curve by the added thermal mass if used bare, but by adding two pieces of wood on either side of the heater block, I can insulate the block against the thermal drop from the steadying vise and atop that prevent scratches.
If you use an adjustable wrench for the heater block, one can add wooden "soft jaws" with a little cyanoacrylate glue, otherwise, some painter's tape or Kapton might aid.
It might help that my small wrenches have a super sturdy surface coating making them rather comfortable to use when left out in the cold and prevents rust. This layer also seems to prevent the flow of thermal energy into the wrench. Note that they are not chrome-plated but more like an enamel-look, a glassy powder-coat or actually lacquered.
Conclusion
When I need to mount something installed on the printer, I do the tightening as quickly as possible - the temperature of the measurement point and the temperature of the nozzle getting pressed into the heartbreak do not drop in the same instance, the nozzle will still be at the aimed for temperature when the thermosensor already has dropped.


How can you prevent the build plate from slipping?

I use kapton tape to fixate the glass plates to the heated beds on two of my printers, one a Prusa i3 clone, the other a CoreXY. The tape is able to withstand higher temperatures, and is very thin, so it doesn't have the drawbacks of limiting the print area or high chance the nozzle hitting the clips.


Do SLA printers have open source slicers available to use?

From what I have researched, each brand of printer has their own method of slicing objects for their printer to parse. For example:

Peopoly Uses a profile for Cura
Creality, Elegoo and Phrozen use CHITUBOX
Anycubic uses their Photon Workshop

There doesn't appear to be any golden ticket type of method (like G-Code) for slicing and providing instructions.


How to create 3D printing file (e.g. STL, OBJ and IGES etc.) from DEM?

This question has been answered on a sister site, GIS Stack Exchange. It's a rather comprehensive answer posted, which means it's impractical to summarize here.

GIS answer

The answer does indicate that a plug-in for QGIS software is needed in order to accomplish this objective. If you do not use/have the QGIS software, my answer is invalid.  All three answers to the question linked above appear to point to the same program/plugin.


What is your source model?  Typically this "missing layer" effect happens if the source has a wall thickness less than the size of the extruder nozzle selected. Cura will view that part of the model as non-printable.

Meshmixer and TinkerCad (among many others) will allow you to set and change thicknesses in the model.


See DesignSpark - DS Mechanical is good, free and fun to use.


How do I wire the z-axis motors in parallel on the Prusa i3?

In the diagram, they do show the wires connecting together, which is right. You can accomplish that just about any way you like, so long as you pair up the wires correctly from one motor to the other.

I'm assuming both "Z" motors are the same type and have the same color-coding for their wires. If not, you'll need to figure out the correspondences first (you may want to post another question if you need a hand with that, since it's pretty specific and generally useful).

Many control boards have "headers" sticking up, with 4 bare pins for each motor. Connectors that plug right onto those are readily available, such as at https://www.sparkfun.com/products/10364.

Some ways you can wire the motors in parallel:

Some control boards, like my RAMPS 1.4, provide 2 sets of header pins next to the Z stepper driver board. In that case, just put a connector on each motor (if they're not there already), and plug them in next to each other.
If there's just one set of header pins (or one Z-motor socket of some other kind) on your controller, make a "Y-cord" by soldering the wires from one connector (that plugs to the controller) to 2 4 pin connectors, one to mate with each motor.
Or you can skip the 2 extra connectors entirely, and just solder the motor wires to the wires from the connector: 2 reds to red, 2 blacks to black, or whatever.
If your controller just has empty holes, either solder in header pins and do as above (preferred, IMHO), or wire directly into the holes, splicing the 2 sets of motor wires if there's only one set of holes.

Motor and connector wires are wildly inconsistent, so make sure you get them sorted out right if they aren't already. The first thing is to check continuity: find 2 pairs of wires, which are the ends of two separate coils. If your motors have more than 4 wires it's trickier.

With RAMPS (see handy diagram RAMPS 1.4 RepRap Arduino Mega Pololu shield),

the 4 pins are commonly labelled (starting from the one nearest the power-supply end of the RAMPS board):

2B 2A 1A 1B

It means coil 1 and coil 2, each of which has ends A and B. I find this unclear because it could just as well have been numbers for the coils, and letters for the ends (if you wire it that way it won't work). So be sure you have continuity (maybe 15 ohms or so) between the wires you connect to 2B and 2A, and between the wires you connect to 1A and 1B.

The really good thing about this pin order is that if a motor is running backwards all you have to do is power off and then turn the plug around. That's one reason I think it's important to keep connectors in there, rather than soldering directly.


How to unload filament as cleanly as possible using the extruder motor?

There's a bit of a compromise here:

Filament cohesion in the nozzle isn't strong enough to remove all residue at higher temperature

Extruder motors can't get sufficient grip / don't have sufficient torque for filament extraction at lower temperatures

That means you'll always have to purge some of the old filament when changing to a new filament.
To easily remove the old filament, you'd want to fill the nozzle, so that there's no large plug of filament that might get stuck in the Bowden tube (as suggested in a comment by Rosalie W), then pull the old filament out; and then purge the nozzle after inserting the new filament.
How much you'll need to purge depends a bit on the filament and its color, but I'd guess 50 mm should be sufficient in most cases.

As G-code, this might look something like that:

;Unloading
G91 ;relative movement
G1 E5 F300 ;fill nozzle
G1 E-300 F3000 ;unload filament, 300 = Bowden length + hotend length
G90 ;absolute movement

;Loading
G91 ;relative movement
G1 E295 F3000 ;load filament
G1 E55 F200 ; purge filament
G90 ;absolute movement


Cause of slicing artifacts layers not connecting diagonal errors

The artifacts you spot in your slices do not come from the slicer, they are actually present in the STL file you export.

I suggest checking your model for problems like vertices that share a position or edges that are parallel but not joined. Use the remove doubles function in blender to merge up these vertices. Then make sure that your surface consists of only squares and triangles to aid the stl generation.


You can, in most slicers, set a separate extrusion multiplier for the first layer. This doesn't appear to be possible in slic3r, but there are a couple of ways to work around this:

Change the Z offset (either in software or by adjusting the endstop). Bring the nozzle closer to the bed for the first layer. You can combine this with an increased first layer height. This is the most appropriate fix for your issue.
Use M92 EX.XXX to increase the extruder steps/mm in the start G-code, then set it back to normal in the layer change code. This emulates increasing the extrusion multiplier for the first layer.


How can I stop the flare out of the bottom layers?

The picture is not very clear so this can be related to either:

Overextrusion at the bottom layer (slicer setting) or an incorrect bed leveling (bed to nozzle distance too small), or
this could be the effect called "elephant foot" that is primarily caused by printers with a heated bed. This issue is related to unbalanced printing parameters: heat bed temperature (too high) in combination with insufficient part cooling.

The general remedy for these problems is to level the bed (e.g. nozzle can be too close to the bed). "Elephant foot" can be reduced by reducing the heat bed temperature, re-positioning the cooling nozzle and/or start cooling at a lower height. Please experiment with the print parameters by printing XYZ 20 mm test cubes till you find the correct settings.


I would assume it is either the stepper driver or the stepper motor. Try switching the motor wires for x and y axis and see if the problem stays with the motor or the driver. If its not physically getting hung up then this is likely. I had the same problem with my y axis and after switching the motor it was gone. It would only skip steps in one direction and that seems to be exactly whats going on. Most likely it was caused by bad windings on 1 of the 2 coils inside the stepper motor.


First few layers are now printing very badly

Well, I guess if I were more experienced I would have checked this earlier.  I tried everything almost tore my printer apart and rebuilt.  One more testing of a cube and the filament broke.  I became suspicious and replaced the filament with another brand and voila, no more printing issues!  Looks like it was the filament.


I am sorry to tell you that SketchUp is not a good software for printable 3D designs due to its exporting feature not properly reducing complexity. It creates unnecessary faces and vertices inside of items on a regular basis, which in the slicer creates artifacts.
To make a SketchUp created file well printable, a huge amount of careful re-engineering in a graphics program like Blender is needed, manually removing the excess vertices surfaces.


Stringing may depend on sub-optimal retraction settings: when retraction is fast and high enough, the string may be cut and disappear.
You may want to at least try to optimise retraction, at least to exclude that parameter.
There is a tool designed to properly tune retraction:
http://retractioncalibration.com/
What it does is print a tower with multiple retractions with increasing retraction distance around the perimeter. Along the Z axis the retraction speed is increased.
This tool does not include Z-hopping so stringing may be less visible, but at least you can easily visualise the optimal retraction settings. At that point if the optimal settings are much different from what you had, you may want to try your model again to see if it improved.


What exactly does calibrating a 3D printer do?

First, welcome to the 3D Printing Stack Exchange!

On bed leveling

Bed leveling, or more accurately bed tramming, adjusts the bed so that it is even in relation to the print head. Typically it is done by sliding a paper between the nozzle and the bed when Z = 0, or the print head is at its lowest. The amount of friction should be similar to the amount of friction of a sheet of paper between two magazines (recommended by Tom Salander on YouTube I believe). One sheet of paper is about 0.1 mm, which is a common gap and allows for good adhesion of the deposited plastic, and typically the gap is measured at the four corners and the center of the bed.

But wait, there's more!

Mesh bed leveling can account for a physically uneven print bed (like a bowing glass sheet) and can be done manually like above or one can mount a sensor so that everything is automatic. The print bed is broken down into a grid (typically 3x3 or 5x5) and the Z height adjusts so that the gap is 0.1 mm at each point in the grid. A mesh is then made and stored in the printer. As the printer prints it makes the necessary variations in height so that the print is flat. Please note that the bed should be leveled as best as possible before setting up the mesh as it will vastly improve the resulting mesh. Mesh leveling is primarily software. The actual level of the bed remains unchanged, thus needing to level it prior to setting up the mesh.

Other calibrations

Bed leveling (including mesh bed leveling) is one aspect of calibration. Other important factors to tune in are temperatures of the nozzle and the bed. For example, PLA has a temperature range of 180-230 °C but each printer is different and may need to print at a higher or lower temperature for best results. Or the printer reports a temperature of 200 °C but the thermistor is off and is actually printing at 190 °C. It's up to the user then to compensate if they want/need to print at an actual 200 °C.

Other settings to tune are print speeds, acceleration and jerk, retraction, and extrusion. Faster print speeds can result in poorer quality prints, namely ghosting and under extrusion. Acceleration/jerk works in the same vein since it directly affects speed. Retraction helps with stringing. If the retraction settings are too low then there will be stringing on the model, if it's too high then there can be under extrusion and heat creep. Adjusting the extrusion factor will tell the printer to push more plastic out or push less. The higher the factor the more plastic is pushed. IMO best practice is to leave the factor at 1 in the slicer and calibrate the stepper motor itself (as can be seen here)

Calibration models

There are several calibration models on thingiverse that can show common print issues. Some of the popular ones are:

The calibration cube which one can ensure that the motors are moving accurately to print out a 20 mm cube. This also shows ghosting along any of the three axes. This cube may also point out if any of the axes aren't 90 degrees perpendicular to each other as the cube should be, well, a cube and not an amorphous shape (thanks to Joel Coehoorn for pointing this out).
3DBenchy which shows a myriad of potential print quality issues including ghosting, poor overhangs/bridging, and stringing.
A Temperature Tower uses post scripting in the slicer to change the temperatures so one can determine the different print qualities across a spectrum of temperature. There are a lot of different models online if this one does not work for you.
An all-in-one test can do a lot of tests in one model and they are all labeled within the model. (The linked one is the mini version, there are several similar tests online.)
This list is by no means inclusive, there are several other models that can test other problems. These are just what's usually printed (especially the cube and Benchy).

Happy printing!


Is iron oxide a suitable material for use in SLS/SLM 3d printing?

First of all, let's start with the basics:
Iron oxide aka rust
The University of Illinois hosts a "Ask the Van", where the question "is rust magnetic" has been asked, and I will quote from Tom J. and Mike W.:

There are several different oxides of iron, with different fractions of oxygen. They are Fe0, Fe2O3, and Fe3O4. Rust consists mostly of Fe2O3, with additional water molecules attached. There are several forms of Fe2O3, and a common mineral composed of Fe2O3 is called hematite, which is a shiny-blackish mineral. Hematite is not ferromagnetic, but it does still respond to a magnetic field and will be attracted to the poles of a permanent magnet.[...] FeO is also not ferromagnetic, but it is pulled about twice as much as Fe2O3 towards the poles of a magnet. Magnetite, Fe3O4, is ferromagnetic, and is about 1/4 as strong as pure iron.

In a followup answer by Mike W., it gets more explicit:

Rust (a collection of some iron oxides) is virtually non-magnetic, unlike plain iron or most types of steel.

This means pretty much, that unlike pure iron, you can't pick up (most) rust particles with a magnet. From all that we know about the Martian soil, we know for sure that it has a very fine grain, so the particles in itself are tiny. This again hints that any exposed iron on Mars has been thoroughly rusted through over the last million years, leaving only non-magnetic rust dust on the surface - dust that is not suitable to be mined with magnets.
We have an analysis of the chemical composition of Mars from some landers, hinting that Martian regolith indeed is colored from its high content of iron in various bonds. So, what we do with that data? We create Maritan regolith simulant, which has been checked back against the findings of the probes. And low and behold: there is not a single percentile of iron in either the findings or the probes or the regolith simulants. Just about 16-18 % rust.
Regolith for SLS?
Now, we have regolith with a somewhat even distribution of rust in it. And we have a stimulant that can be acquired from Huston. To my knowledge, it has not yet been tested for SLM, but it has been used in powder based extruders, as explored in How does this Martian habitat 3D printer built for NASA work?
With the lack of testing and the relatively low iron oxide content, I am hesitant to say that it will work to print in the usual way. However, with the addition of some polymer, one could create a fast regolith-plastic compound that shows similar behavior to concrete. This material could be made suitable for 3D printing in SLS machines. Another idea might be to go from SLM (selective laser melting) to the older SLS (selective laser sintering) or even simple sintering, in which a compound is pretty much "baked" into shape without fully melting it. We understand well how to sinter materials we have trouble with melting otherwise, and one of the prime examples is tungsten carbide.
Conclusion
While I see problems with mining iron from Martian regolith without a chemical refining process or refining it akin to iron sand, I don't see how martian regolith can't be refined into a suitable SLM or SLS material by addition of some kind of polymer or a thermal and mechanical process to achieve sinterable material. Instead of a polymer, a pure metal (magnesium or aluminium) could be added as a binder too. With the availability of regolith simulant for research, it only takes a research group that is interested in researching the suitability of this material for such applications.


What's smoother? Acetone treated PLA or ABS

ABS filaments will smooth well with using acetone, it's been used for a while now.

For PLA filaments it's a different story, pure PLA will not smooth out in acetone and it will likely only cause structural failure of the product.

However most PLA filaments aren't pure PLA, they contain additives including ABS that react differently when exposed to acetone and the reaction will really depend on the manufacturer of the filament, only a few PLA filaments are known to smooth like ABS when in an acetone vapor bath, it is the case for ColorFabb PLA filaments and it is absolutely not the case for bq PLA filaments that only soften and break when exposed to acetone.

You'll have to make small tests with different brands of filament to see which smooth well and which don't but if you want to go fast either go with ABS or use other smoothing techniques such as sanding + 3D print Smooth On epoxy.


On my TEVO Tarantula, is there a way to test that its heater pins are working?

I haven't tried it, but would assume you could put a multimeter (set to VDC) onto the two connections for the heater pins and check the voltage output during what would be the heating period. If there's voltage output, your heating element would be at fault.


PID Autotuning not working – large initial overshoot, no oscillations

I recently experienced exactly the same problem. For me it was related to an incorrect heater cartridge. I accidentally used a 12 V cartridge in a 24 V powered system.

The heater element got accidentally mixed up between the higher voltage parts container and I forgot to check the resistance. Inserting the correct voltage heater immediately fixed the problem, but it did require a retune of the hotend.


Your description sounds indeed as if the PID is not correct. You can try autotune with M303 only if your heating cartridge is not absolutely overpowered. However, in such a case you typically also have an overshoot, which you don't mention in your description.

In that case you need to lower your duty cycle (by the BANG_MAX parameter in the firmware) a bit. Otherwise autotune fails, because your heating cartridge overshoots even at small gains.

Out of the box I would suggest you to increase your D-term and decrease your I term if it cycles like that. For most printers, I used, a ratio like that is sufficient: 4/1.5/25.


Usable build volume of a Makerbot Replicator Plus?

Exactly what software are you using to slice?  From your description, it appears the gcode was successfully generated, but the software choked when trying to draw teh preview image. That could be due to lack of local RAM or problems with memory leaks in the software.  This happens when the number of layers and the complexity of the layers gets large.

Try just creating a plain rectangular solid and set a large layer height.  Let us know what happens with that.


Why does my MKS Base not recognize my thermistors?

You should:

Ensure that firmware has proper thermistor configuration. For details see this video tutorial.
Verify that your thermistor works properly. Measure voltage on it. It should be around 5V on this particular board.
There is possibility that the board is defective. Replace it.

Temperature sensor possibilities for Marlin firmware:

// -2 is thermocouple with MAX6675 (only for sensor 0)
// -1 is thermocouple with AD595
// 0 is not used
// 1 is 100k thermistor - best choice for EPCOS 100k (4.7k pullup)
// 2 is 200k thermistor - ATC Semitec 204GT-2 (4.7k pullup)
// 3 is Mendel-parts thermistor (4.7k pullup)
// 4 is 10k thermistor !! do not use it for a hotend. It gives bad resolution at high temp. !!
// 5 is 100K thermistor - ATC Semitec 104GT-2 (Used in ParCan & J-Head) (4.7k pullup)
// 6 is 100k EPCOS - Not as accurate as table 1 (created using a fluke thermocouple) (4.7k pullup)
// 7 is 100k Honeywell thermistor 135-104LAG-J01 (4.7k pullup)
// 71 is 100k Honeywell thermistor 135-104LAF-J01 (4.7k pullup)
// 8 is 100k 0603 SMD Vishay NTCS0603E3104FXT (4.7k pullup)
// 9 is 100k GE Sensing AL03006-58.2K-97-G1 (4.7k pullup)
// 10 is 100k RS thermistor 198-961 (4.7k pullup)
// 11 is 100k beta 3950 1% thermistor (4.7k pullup)
// 12 is 100k 0603 SMD Vishay NTCS0603E3104FXT (4.7k pullup) (calibrated for Makibox hot bed)
// 13 is 100k Hisens 3950  1% up to 300°C for hotend "Simple ONE " & "Hotend "All In ONE"
// 20 is the PT100 circuit found in the Ultimainboard V2.x
// 60 is 100k Maker's Tool Works Kapton Bed Thermistor beta=3950
//
//    1k ohm pullup tables - This is not normal, you would have to have changed out your 4.7k for 1k
//                          (but gives greater accuracy and more stable PID)
// 51 is 100k thermistor - EPCOS (1k pullup)
// 52 is 200k thermistor - ATC Semitec 204GT-2 (1k pullup)
// 55 is 100k thermistor - ATC Semitec 104GT-2 (Used in ParCan & J-Head) (1k pullup)
//
// 1047 is Pt1000 with 4k7 pullup
// 1010 is Pt1000 with 1k pullup (non standard)
// 147 is Pt100 with 4k7 pullup
// 110 is Pt100 with 1k pullup (non standard)


3d prints come up with ribbing on one side

Hmmmm In my experience when a printer has that bad of wobble it is still the Z axis. Your rods might be good, but are the two Z axis the exact correct distance and equal distance on the printer frame? Imagine that you had one a few millimeters too far out. How might the rods act? Mayhaps, over the course of several layers, they would slowly drift back and forth? Creating a period effect on your print? What do the top of the rods do over time? Do they move a lot if you go from height 0 to 100mm on z?
I have a few ideas. What happens if you loosen you Z motors so they can move around their mount? I had to do that on my Prusa back in the day. I think for that machine the Belt was actually too tight causing the issue. Current printers are usually better designed so its unlikely that is your issue. Also measure the distance between the top of the rods when the carriage is at 0, and at max. You should see very little variance.
If it was on both sides I would say it was bad PID calibration. IE this simplify 3d link
Though you can see on this forum the fellow had a bad coupler. So still mechanical.
Also could be back lash / belt lash.. but unlikely


To Protect, or Not to Protect

From the web site you reference:

  The SilentStepStick Protector is an add-on module for StepStick and
  Pololu A4988 compatible stepper motor drivers. The board provides
  flyback diodes (freewheeling diodes) for the motor outputs, so that
  they are also protected against induction voltages in the unpowered
  state of the driver.

  The v2 protector also contains a diode from the logic voltage (anode)
  to the motor voltage (cathode), so that the power supply order of all
  SilentStepSticks is always guaranteed.

Since I assume you've read this, please indulge some explanation of the electrical engineering.

Motors

Every motor has a part called the "rotor" that rotates, and a part called the "stator" that is stationary.

In the stepper motors usually used in 3D printers, the rotor is a permanent magnet and the stator consists of coils of wire.  In normal operation, the current flowing through the coils creates a magnetic field.  The rotor aligns itself with the field of the stator.  To move, the stator field is shifted by changing the current in the coils, and the magnetic force causes the rotor to rotate to align the fields.

Generated Voltages

As Faraday discovered, a changing magnetic field induces a voltage in a wire.  There are two ways that the magnetic field changes.  The first is that the current changes or stops.  That introduces little high voltage blips into the motor coils.  The motor drivers are well prepared to handle this blips.  The second is when the rotor is forced to turn by an outside force, such as sliding the bed.  As these voltages are not related to action the motor driver is causing, some of the techniques used to handle the voltage spikes may not be as robust.

The protection boards you point to consist of diodes to limit the magnitude of the voltages that the coil can produce.  This is redundant with the diodes and protections built into the driver chips, but it may offer stronger protection.

Benefits?

In this responder's opinion, you are unlikely to see a great benefit from these boards, but perhaps there are vulnerabilities I am unaware of.  You are also unlikely to do any harm.

You asked specifically if, with the protectors installed, you could unplug the motor while it is passing current.  The protectors may help with that, or they may not.  Interrupt the connection creates a spark, and arcing through the air, that makes many high-frequency components which may not (or may) be effectively clamped by the diodes.  For best results, you could add the protectors, and also avoid interrupting the motor current while powered.


You can do so by placing this at the top of the start code under machine settings (tested on 2.6.1).

M104 S{material_print_temperature}
M190 S{material_bed_temperature}


Gizmo3D SLA + Monocure resins not curing

I get best results from sun curing by putting it in water in the sun for 20-30 min.

I personally do not like Monocure Red one. I find the Nova3D prints better, has a lower oder, and cheaper.


How do I determine the acceleration value for my printer?

As Tom pointed out, binary search is the best way. In case that term isn't familiar to all readers, here's a little more detail:

Establish an acceleration value that you're sure is too low (call it $L$), and one that you're sure is too high ($H$). It sounds like you know such values already from experience.
Figure out the speed in the middle: $(L+H)/2$.  Call that $M$.
Try printing at speed $M$. Something like a stepped calibration cube might be a good choice of object (plenty available on Thingiverse).
If $M$ is still too fast, take $M$ as your new high-speed limit (that is, reset $H$ to the value of $M$), and repeat from step #2.
If it's slow enough to work, take $M$ as your new low-speed limit ($L$), and repeat from step #2.

Each repetition will cut the range in half. Keep repeating until $L$ and $H$ get as close as you want; say, within 5 % of each other or so.

I wouldn't bother trying to get super-close, because the workable value will vary somewhat over time (friction from dust getting on various parts; slight voltage differences; different mass and pulling tension for the filament roll, temperature of motors, complexity of the object you're printing, behavior of the slicing program you use, you name it).


OpenSCAD to Flashprint ruins model based on number of fragments

Your image is very helpful. I think you might find that the rendering in your slicer is intentionally degraded to minimize use of system resources. The image you see may not be an accurate representation of that which would be printed.

If you wish further confirmation, consider to create the g-code from the slicer and view it in a text editor. An even better option would be to use an online g-code viewer and observe the results of the created g-code.

The image above is the first line of print for a Marvin, showing that the base curves are smooth and clean. Your cylinder should appear in a similar manner, confirming that your slicer is degrading the image.


Linking an Arduino Mega with RAMPS and an Arduino Uno with CNC Shield to control more stepper motors using Marlin firmware

so points to that case:

how are you going to sync master/slave?
adding more steppers to master (even only for pushing control to slave) will limit speed in the whole system (this is mainly one of the reasons why we shall go to 32-bit platforms to print faster).

As marlin will give you a good grasp to convert g-code into steppers movement, then if you are willing to double or triple steppers number per axis, you can grab dir and step signal and forward it to other steppers drivers without the mess of syncing movement in time and board. If you are going to add a special tooling - then you shall add your mods to firmware as well.


How to add internal supports/localized infill, preferably in Cura?

I'm not really sure if i get you right but it seems like you gotta switch on support material. That's all. Correct me if I'm wrong but it sounds like very common situation where some parts are hanging like your yellow disks.

Otherwise if your model is going to be closed at the bottom and at the top you can mock support on your own to have better control of it. How? Just add hollow cylinders under your disk so in fact cylinder will stay on the bottom layer then its walls will be support and finally your yellow disk will be a top cover of the cylinder. I hopw you can imagine that properly.

Another way is to design support elements wich would grow out of walls and this way support your disks

Maybe if you would explain a bit more, what the model is then I could support you more.

[edit]

To make it more automatic, you could try to use parametric CAD apps. I would say, Autodesk Inventor is one which I can suggest. You can use for example its Ribs functionality as support (varsion C).

[edit2]

After Tormod Haugene's and tbm0115's comments I decided to fill some gaps in my answer. Here go pros and cons of options A, B and C.

option A

The simplest one and more or less automatic one. Which means when user add support then this option will be a result of it. Of course if user needs to have support only for the disk but over the disk there will be... a "ceiling" then option A cannot use regular support as it will generate a support also for the ceiling. For such situation user needs to add a cylinder manually (filled one) or

option B

User can add hollow cyliner (just its walls). This option can give similar or higher stiffness as regular support because solid walls increase endurance tahn thin support grid.

option C

This option (my personal choose) has some advantages unavailable in A or B option. First - support doesn't have to have "ground" base. It means the yellow disk can really hang even if there is no bottom layer at all. Second - it joins walls with disk and walls together so the stiffness concerns other surfaces.

Depending on needs the cylinder (option A or B) can be transformed into a cross or pillar (thinner than cylinder itself). It can be more taper expandint to the top or to the bottom.

There could be even option where the above one would be joined with option C. So these (3) ribs would raise from the bottom but not from the walls.


How to probe twice while mesh bed leveling with a BLTouch setup

For the 1.1.x (1.1.9) bugfix firmware version, the multiple probing is defined in the configuration.h file.
// The number of probes to perform at each point.
//   Set to 2 for a fast/slow probe, using the second probe result.
//   Set to 3 or more for slow probes, averaging the results.
//#define MULTIPLE_PROBING 2

You should change the configuration to include the multiple probing by uncommenting the line:
#define MULTIPLE_PROBING 2

Note that there is question: "Updating Marlin Firmware - Step by Step Guide" that shows how you should modify the sources.
How to compile and upload/install the compiled binary on your printer controller board depends on the controller board version and type.


that sounds like layer shift... you might have one of these issues

overtightened the carriage wheels.
a loose Y-belt.
something getting into the bed's cable, resulting in drag.


Best filament to use in high humidity environment?

You don't provide information about the part, but in general PETG, ABS, ABS plus/Pro and ASA are not going to have any issue with humidity for a long time. If it's outdoor, avoid ABS and use PETG or ASA.
What is important is to keep the filament dry BEFORE printing. After printing, no problem. In fact, nylon after printing can be wet on purpose to significantly increase impact strength (and reduce tensile strength).
PLA in high humidity environment may lose some of its strength, but there are PLA parts under the rain which hold perfectly for long time, if they are not loaded significantly.


Consider that the string you are seeing is the nozzle wiping across the surface, especially if you are not getting stringing via your test part. As you suggest, it's not unlikely that the layer viewer is showing movement and not extrusion.
Check your z-hop settings as well as the other references in the linked page. Z-hop will drop the bed by the set amount when traveling with retraction.

The other useful reference is combing, which limits the travel of the nozzle to remain within the boundaries of the print and also removes the requirement of retraction. It may leave nozzle traces, although that reference is not in the linked page.

All images attributed to linked page.


How to connect power and fan to RAMPS 1.6?

You only need to connect one pair (one red, one black) of sufficient wire gauge to the single power connector's plus (red) and minus (black). There is no need to bundle multiple pairs from the PSU. Some pinout graphs are not clear in this respect! I've always connected the heated bed through an external MOSFET to keep large currents away from the board, but according to the design, it is capable of handling the current.

E.g. this is the correct pinout:

And this an incorrect pinout graph (look at the lower left where the power needs to be connected to the board, this hints to bundling the 11 A and 5 A wiring):

The part cooling fan should preferably not be connected to a (non-schedulable) 12 V header. Instead you should use the D9 output connector to schedule the airflow of the fan for part cooling.

Note there is no spare 12 V header available on the board. You could use the spare PSU pair to power the coldend (radiator) fan.


I've personally had this happen when I had a minor clog in my nozzle.

My first steps to fix this would be:

Make sure the exterior of your nozzle is clean. I've had bits of plastic pull at the extruding filament and change it's direction.
Attempt a "cold pull" or "atomic pull". On my Replicator 2 I do this by removing the extruder motor, heating up the hot end, manually pushing a length of filament through the nozzle, letting it cool slightly and tugging the filament (and hopefully the clog) out of the nozzle.


After 1.5 hours of printing quality degraded

This is very likely under extrusion caused by your feeder pressing down too hard onto the filament. If the feeder presses the filament very hard it then gets squished a bit, this is not causing much issues when you're only feeding in one direction as the drive gear is still pulling on fresh filament and shoving the squished part down at a steady rate. BUT once you got retractions things get awful as the squished filament then gets retracted and fed again at the same pace but due to the elongation at a smaller rate of material causing underextrusion.

You can either trade it in to some overextrusion by adjusting the extra length on restart setting, retract a shorter piece of filament (like only retract half a mm or something) or loosen the feeder so it doesn't squish down on the filament as hard.


How to draw cube with cone (Dreidel like), using Onshape?

After rejecting the intense interrogation process for signing up with Onshape, I've settled for a general description based on common practices in 3D modeling.

You would create the rectangular solid representing the cube, as well as another rectangular (or cylindrical) solid slightly larger than the first one.

Create also a cone shape with the dimensions appropriate to the segment you wish to have remaining on the first solid.

Using Boolean operator or the equivalent, subtract/difference the cone shape from the second solid, resulting in a "pencil point" shape of empty space in the second solid.

The skirt of the cone is barely visible in the image above and is transparent, the TinkerCAD™ version of subtraction.

Once grouped in TinkerCAD™, the entire cube becomes a subtractive body.

Place it in the appropriate position over the first solid and perform a second subtraction/difference or Boolean equivalent.

As one may note, the original cube was not tall enough and had to be stretched to provide the desired result. Not visible in this image is that the subtractive shape was not centered on the cube and resulted in an off-center final solid. Easily corrected with alignment tools, but an important aspect when performing Boolean operations. Control-Z is your friend.

The above steps work with OpenSCAD™ as well as Fusion360™ and even within TinkerCAD™ but the specific steps/sequence varies from one program to the other, of course. This example was performed in TinkerCAD™ because it was the fastest method. Fusion360™ would have stretched my abilities to accomplish the same result, due to my minimal experience with that platform.

I am not surprised to discover and easily locate an exact tutorial for OnShape™ that covers the boolean subtraction process. The images are complex within the tutorial, but the process and concepts are identical. The video accompanying the tutorial is also well done and explains clearly the steps involved.


Updated to match the improved question format.

There are a few ways to reduce material usage. First is what you have touched on. Which is to reduce the design by punching out holes, and removing all material that does not add anything to the structure. Even better is what you touched on, reducing it to the point where your print is more like a suspension bridge, where it is a the bare minimum scaffolding in a geometric pattern.

Most tools you will find for reduction are like this tutorial from Shapeways on Meshlab where you reduce the surface detail. It might be worth exploring these a bet, however probably not what you really need.

Next the more hard core cad tools such as solid works will allow you to preform Parametric optimizations and Topology Optimization.
Topology Optimization. seems to be your real winner

Now from the 3d printer standpoint we just simply tweak our slicer settings. There are entries for Infill. I usually print with 7% infill. AKA my print is 93% hollow inside. I then set a few solid shell layers. Think of solid shells as the skin. Usually that is enough to reduce my plastic usage. The only reason I don't make a part 100% hollow and a few solid skin / shell layers is that I need something to print on top of or if I need the part to be strong . Even low percent infill can be very strong if the correct geometric pattern is used (I.E. triangles).

Generally the reduced infill will be enough, unless you are making thousands of this item, though in that case you are probably not going to 3d print it anyways.

3dprintingforbeginners has a nice article on the relationship between infill, number of shells and part strength. A bit more information about the terminology (infill/shells/etc...) can be found on 3D printing blog.