Slic3r top layer issues, small gaps, weird extruder paths

To have a very smooth finish on top layer, I usually act on these settings :

in Print Settings :

Layers & Perimeters :
  Horizontal shells : 3 / 3

Infill:
  Infill, Top/bottom fill patterns : Archimedean Chords ;

Speed:
  .for print moves :
   Top solid infill : 20  (mm/s)

Advanced:
  Extrusion width, Top solid infill : 0.2 (mm)

= This gives very slow movement in a circular way, the small extrusion creates an ironing effect, thus very nice finish.

Considering your slicer behavior, have you tried changing number of top shelves & Infill type ?


Printrun doesn't connect when 12 V is on

It sounds a bit like you are having (additional) grounding issues1. Are your MacBook and the RAMPS using the same ground, i.e. are they using the same mains circuit?
If you are using the same power strip, then the next thing to check would be that the PSU on the printer correctly grounded (at the bottom of the unit).
From David Crocker's superlative blog, see Upgrading the large delta printer - Power supply output grounding:

Power supply output grounding
While taking some measurements on my machine, I discovered that the
negative side of the output of the 12V LED power supply I am using was
not connected to ground inside the power supply as I expected. This
presents a safety hazard. So I added an additional wire from ground to
the spare negative output terminal of the power supply.

1 Why do I think this? Three reasons:

Because grounding issues is one of the most common, and over-looked, problems, in circuit design;
I have often had peripheral devices, that use a separate additional power supply, cause a PC laptop to go "haywire" (or worse, die) once connected via RS232/USB (especially charge sensitive devices on the laptop, such as the track pad), due to different, or floating, grounds, and;
I had recently read the blog and made special note to check all of my power supplies as they are all terrible, cheap, Chinese knockoffs, and grounding circuits in Thailand are usually non-existant, or, at best, poorly wired up.


You can change the maximum allowable feedrate in Configuration.h, but the actual feedrate that is used isn't determined by your firmware. The feedrate is specified in the G-Code file. A command like

G0 X10.0 Y15.0 Z3.0 F9000

indicates a move to (10,15,3) at a feedrate of 9000 mm/min. If F is not specified, the last used feedrate is used.

You just have to provide the appropriate G-code commands with the feedrate you want in them. There's no reason to modify the firmware to get a different feedrate.


The molten plastic in the extruder becomes a hydraulic fluid effectively when it gets melted. You're pushing on a fat piston (1.75 mm or 2.85 mm, depending on filament type), and shoving fluid out through a 0.4 mm or so hole. There's a limit to flow rate at a given pressure, but the bigger issue actually tends to be friction. Molten plastic really loves to grab on to metal, and the ratio of surface area to volume is fairly high in the long, skinny tube that is the inside of an extruder. To make matters worse, the not-quite-molten section of the melt zone up at the top normally doesn't make a lot of contact with the walls due to lower pressures not deforming the plastic all that much, but at higher pressures you get much more deformation, increasing the linear distance that the plastic is dragging against the tube walls, and the pressure with which the two surfaces are bonding together. Especially in cheapo clone extruders you'll find roughly bored inner surfaces with many circumferential grooves which exacerbate this issue - this is why most extruders have a PTFE lining as far down as they can go. I had this issue in my $3 "all-steel" extruder barrel, where even printing PLA was an issue because of how readily the plastic formed huge plugs and grabbed the inside of the extruder.

So what you end up with, is that increased torque mostly linearly translates to increased pressure, which results in linearly increased friction inside the barrel, plus a little bit extra due to extra deformation in the top of the melt zone. You can polish the inside of the barrel (heatbreak? seen both terms) to help alleviate internal friction somewhat.

To make things even more fun, there's obviously a limit with how much force you can exert through the mating surface of a single hobbed bolt and the side of the filament. Too much force and the teeth will simply rip off the side of the filament and then you'll have no feeding torque whatsoever. To get much higher torque you'd need to design an extruder that both supports the filament much better than modern designs do, and spreads the force out over a larger surface area, either by using a much larger diameter feed gear, or multiple tightly-coupled feed gears.

I went into some degree of detail on the feed mechanism in this answer that another user asked about using a commercial extruder for plastic injection molding, which overlaps somewhat with your question here.

I know the original question assumed perfect heat transfer that was not a limiting factor to the process, but how that actually works is relevant to the question as well. E3D took one approach with their Volcano design, simply by making the melt zone much longer to increase heat transfer; the downside is there's obviously substantially more friction when you've got 4x the linear distance of molten plastic against metal, assuming you're not using a PTFE liner. This does have the advantage of letting the plastic take its time to reach the target temperature, decreasing how far over your target plastic temperature you need to have the heating element. One thing not often discussed in 3d printers is the fact that the plastic asymptotically approaches the temperature registered on your thermistor. If you're printing very, very slowly, your plastic will nearly be exactly at the target temperature. If you print very quickly with very high volumes, you'll tend to have slightly cooler plastic than intended because it simply wasn't in contact with the heater long enough to come up to temperature. The solution for very small designs might be higher temperatures, but the drawback there is that if you slow down even for a moment, say moving to thinner line widths or picking up and moving the extruder, you'll overheat the plastic. So there's practicality questions that need to be answered to determine how you'll actually heat that much plastic to the right temperature. Increased distance improves reliability at the cost of increased friction (and therefore extruder torque required), and increased temperature mostly bypasses that question at the cost of reliability.

TL;DR Increased extrusion speed requires increased pressure, which increases friction dramatically and in a non-linear fashion and results in stripped filament.


Internal wall does not print in horizontal print orientation

I think this is caused by the shape of the hole. The shape is parabolic or circular, this means that if you slice it as in the green part, the slicer determines the placing of the layers along the curvature. If it has a shallow curvature, and slicing layer height is relatively thick, the curvature of the object cannot be followed. But, if you have more than 1 top layer, this usually should not be visible. I don't think that you have a single layer, so this is a pretty odd anomaly that I have not seen yet (that you look at the infill without top layers).

You could get past this by using a local different infill, e.g. 100 % infill. You can look at this answer of the question: "Different infill in the same part". This should help you out printing in your preferred orientation.


I had a similar problem to you with my Ender-3 but now it is fine.
There are so many causes of under-extrusion that I doubt I can tell you what is specifically wrong in your case but perhaps I can give you some pointers.
In addition to what you have done, check if you can manually extrude the filament by releasing the grip on the filament (depress the lever on the feeder mechanism) and push the filament through with your hand (while the nozzle is heated to the correct temperature for your filament).
If that works well without too much force then it suggests one of two things:

an issue with the feeder mechanism (e.g. worn or clogged up teeth on cogs, spring too tight or too weak) or
extrusion settings on your slicer need modification (e.g. your slicer made G-code with too frequent retractions and this causes the filament to wear down thin preventing the extruder feeder cogs from gripping it. A solution is to reduce the maximum number of retractions possible by altering your slicer settings - this was an important factor for getting my machine to work again).
I found the following YouTube video helpful in giving me pointer of where to start - perhaps it will help you too:


No, you did not set all the settings to the same speed, there are 2 different print speeds defined:

Infill Solid: 60 mm/s
First Layer Speed: 30%

This means, that some walls will be printed 10 mm/s faster than the others, and that first layer should be printed at 30% of 50 mm/s, so at 15 mm/s - try to define it as a speed. Make sure to save and apply the settings and only then slice your model, as you might have sliced the model with the previous settings.


Ender 5: Bowden tube shifts in/out of extruder during retractions

If it's just the pressure fitting on the brass coupler that shifts in/out, or the PTFE tube shifting slightly in/out but remaining in the coupler, that shouldn't be a problem unless it's so loose it can come out entirely. The blue clips which should have come with the printer are intended to stop this motion or at least provide enough pressure to prevent it from falling all the way out.

Regarding the small 0.25 - 0.5 mm of play, effectively it just means you lose that much length from your retractions, since part of the retraction goes into pulling the tube back into the coupler. When the retraction is reversed, the effective filament position should go back to what it was before the retraction. As long as your retraction amount is sufficient after the loss, it should not cause stringing.

You probably need to look for another cause of your stringing.


Most of the aluminium alloys are fine.
When they say that a certain aluminium is not suitable to certain temperature range they usually mean "under stress"... your bed has no stress at all, it's just staying there with basically no weight on top of it.
Also, you don't need the single micron accuracy either...
Just pick a "cast" and milled aluminium and not a rolled one.
If you can choose among different ones, pick the one with the highest thermal conductivity, and that's it. For example, I can easily find milled plates out of 5083 or 7021. 7021 has a better thermal conductivity, which is good to have a more uniform temperature.


I printed the thing for some layers to see what the printer actually does:

There are clearly too many retractions and unretractions.

This can be seen in advance by letting Slic3r show the retractions and unretractions.

For the green "walls", it became clear that it prints them exactly onto the empty space, so in fact the seem to be floating.

That made it obvious to me: the normals were pointing into the wrong direction. Therefore, Slic3r seems to have interpreted the material side of the green parts inside out. I had the same issue on some other parts as well.

I went to Blender, selected the object(s), chose edit mode and found a function called "Recalculate normals". Since then, the bottom layer is solid.

Also printing time is reduced by half an hour.


Anycubic Kossel Plus raises the Printhead around the corners of the bed too High if the print is too close to the corners

It is a common  problem with "delta"-style circular parallel kinematics machines.  It is called Bowling.  It can lead to the presumed Z=0 plane having a bowl-like shape.  The actual error shape can be more complex.  The job of "bed-leveling" is to make the realized z=0 plane to be identical with the bed.

If you can, use a multi-point (like 40+ points) interpolation.  It builds an error map, and adjusts every point based on that map.


Printing multiple materials with different properties on the same device

Yes and no.

  for instance simultanious printing of plas plastic and lets say metal. Is such a printer available or in development ?

Practically speaking, no.  Metal printing requires significantly higher temperatures than plastic, and the two processes are so incompatible that there is currently no good solutions that would allow one printer to print both in the same print. Whether extruding filament, laser sintering, or curing resins, the materials involved have to be fairly similar in processing environment to print adjacent to each other without issue.

There are many printers that are intended to print multiple materials by changing the print head.  You might, for instance, use a ceramic paste extruder, then change the head for the next print using plastic.

There have been efforts in the past, and some efforts are ongoing, to resolve this.  For instance wood's metal, a low temperature alloy, can be poured at temperatures compatible with plastics, so it's possible to create a printer that prints plastic, leaving troughs or voids in the plastic, then the same printer during this print would pour molten woods metal into these areas, which then solidifies into an internal metal structure.  These are intended for circuitry and electrical use, however significant problems still exist because the thermal expansion differences in these materials lead to stress and result in poor reliability.

So while some of these processes are being developed, this is still just in the experimental stage and there are significant problems to overcome before printers can print widely different materials in a single printing session.

Of course you can find plastics with such a wide range of characteristics that they can be seen as printing different materials.  Plastics imbued with wood fibers, printing next to conductive plastics with graphite, printing next to flexible plastics, etc, etc are now possible, and depending on your requirements they may meet your needs.


Is 22-Guage Stranded Hookup Wire the correct wire to connect the Switching Powersupply to RAMPs 1.4?

22awg wiring is good for a max of 7A in this usage case. Your power supply can provide 30A. So it is definitely not large enough wire gauge for good wiring practice -- in the event of a short, you want the PSU's over-current protection to kick in before the wiring overheats. That would mean 14ga between the PSU and board. 16ga would probably cover your actual load requirements just fine, but we need to know a lot more about your printer to say that for sure.

12v systems need heavy duty wiring, at least on the main supply lines. You can use 22ga for individual power consumers, such as fans, extruder heaters, etc. (No heatbeds.)


The Alunar firmware you linked is a fork from the main Marlin firmware. If the bed Y direction is reversed, usually the stepper is incorrectly placed (mirrored) this is seen frequently for the Anet A8 printer which is very similar to your printer. In your case the X direction is wrong, this is usually related to the wiring of the stepper, reversing the connector by 180 degrees should do the trick (hardware solution). As a software solution, changing direction is not difficult in Marlin based firmware; you just want to invert the stepper direction; the following section in the configuration.h file does that for you:

// Invert the stepper direction. Change (or reverse the motor connector) if an axis goes the wrong way.
#define INVERT_X_DIR false
#define INVERT_Y_DIR false
#define INVERT_Z_DIR true

Just change INVERT_X_DIR to true.

If your home position is still not working for you, you should look into this section of the same configuration file:

// Travel limits (mm) after homing, corresponding to endstop positions.
#define X_MIN_POS -33
#define Y_MIN_POS -10
#define Z_MIN_POS 0
#define X_MAX_POS X_BED_SIZE
#define Y_MAX_POS Y_BED_SIZE
#define Z_MAX_POS 240

Change the MIN_POS positions as such that it starts at the corner of the bed. A more in depth bed center calibration tutorial can be found here.

P.S. Please do not print anti-wobble caps for the Z-axis rods (as mentioned in another answer), these are not reducing the wobble, in fact they cause problems. What happens if you constrain the top is that you get a statically indeterminate construction; forces and displacements are not predictable! Better solutions to eliminate Z-wobble are lifting devices that decouple X/Y movement from the threaded rod (eccentricity of the threaded rod) from the Z movement. Also fixate the threaded rod above the springy stepper-to-threaded-rod coupler.


Gnarly filament: just one of those things, or grounds for complaint?

Sorry to say it, but MOST wrap-unders are caused by end-users releasing the free end of the filament when handling the spool. It is mathematically impossible to introduce a knot during initial spooling, and all the reputable filament vendors these days have pretty careful free-end control when the spool is taken off the spooler and sent to packaging.

Where you may get knots straight from the filament vendor is if they're respooling very carelessly and let go of the free end. You should only see this with very cheap filament.

So, it's possible that your vendor messed up, but you should probably rule out your own handling practices first. It's not hard to prevent losing the free end. The nicer spool styles these days have holes on the side-flanges for securing the free end during handling/storage. Or you can print one of many, many filament clip designs from Thingiverse or your favorite model site.

If you're very careful with handling and still get knots, switch suppliers. Anyone sloppy enough to repeatedly mis-handle new spools is likely also using extremely cheap material, and there have been a lot of anecdotal reports of very nasty industrial chemicals being mixed into the colorants of low-cost filament.


3DTouch sensor fails after probe deployment and triggering

After troubleshooting I have managed to fix the sensor problems.

(Please take note of the update at the end of the answer below as the problem started again shortly after the so-called fix...)

Digging into several posts I found this post that hints to a solution:

After readjusting, the sensor worked and I was able to produce a print, but the next day it failed again... What I found is that the bed and extruder are NOT shut off while probing although that should have been enabled in Marlin 1.1.8. I assumed that this de-powering is only during the actual probe lowering, so very short. So I figured that this might be an EMI problem. In a last resort I updated to Marlin 1.1.9 which has the functionality to shut the power off for heater and bed and everything now seems to work perfectly. I now see that the de-powering is a bit longer and in fact the extruder temperature drops slightly, this has never been seen with the previous firmware version.

Update:
Not long after the "update"/"fix" the problem manifested itself again... Further troubleshooting revealed that it was a bad connection of the connectors of the sensor that got temporarily "fixed" as the cables had been fiddled with during the firmware update.


Ender 3 Calibration Cube Fail + Can't Print Circles

First, check that the calibration part you have is actually a cube. Maybe you downloaded a trick 'calibration cube' model. Cura will show he overall dimensions of any model which it is slicing.

Ignore any print quality issues first off. A hollow calibration cube is mainly used to check the X/Y/Z motion and so long as you print at a sensible (slow) speed), the other parameters shouldn't have much effect (so long as the first layer is OK, and you get within 30% of the right extrusion).

If the calibration cube is within +/- 0.5mm on each side, it's probably good. Under/over extrusion, caliper technique, etc, can explain this sort of variation, and you might want to use a bigger test part like this star on my thingiverse account once you think you're close.

The 'steps per mm' setting is determined within the firmware, it is part of how your printer consumes G-code. For a delta printer, for example, there is some fancy maths to combine X/Y/Z into the motor movements. This means that you can't change steps/mm in Cura, you need to either change the firmware defaults and 'reset to factory settings', or modify the parameters in EEPROM by sending G-code.

Seeing too small a calibration part (for a Cartesian printer) can easily be explained by problems in the printer's motion system:

Stepper missing steps due to jerk or acceleration too high
Stepper missing steps due to binding/friction in the bearings (Send M84 to idle the stepper motor, and move X by hand)
Teeth missing on the drive belt (may show up on a diagonal 'bar' print)
Loose drive pinion (maybe backlash on the flat on the spindle means the problem is greater on small parts) - see below
Flex in the drive mechanism (e.g. belt mount to traveller is loose)

An annoying feature of a lot of these problems is that for any particular repetitive sequence of steps, you might see a very consistent result. Even thought to problem is something being badly adjusted, it gives the impression that the problem is calibration.

The drive wheel is held in place with a grub screw, see this diagram from the Anet-A8 assembly diagram.


What's the advantage to deploy 3D printing on IaaS

Most cloud models are based on virtual rather than physical services.

The closest thing I can think of as "IAAS" in the 3D printing space would be something like 3DHubs which connects people that have printer capacity with people that want to print.

The whole cloud 3D printing thing seem a bit questionable to how large/viable of a market it really is.  I know there are a LOT of people out there that want to make money off of (or at least defer the cost of) the printer they bought; but, the market seems over-saturated.  Heck, even UPS does it.

All the people that I know that use contract printing already have their own printer but contract out either for more volume, or a different material than they can print with their printer.  At work we have a printer; but, we go outside if we want volume (hundreds of pieces) but are not yet ready to commit to a mold.  When we go outside, we would only consider a trusted vetted supplier - not the cloud.


Wiring BLTouch V3.1 on Anet A6 and the JST connector polarity

Black is GND and should not be connected to VCC.
Note that you can simply pop out the metal parts (use a pin to press a small clip) from the connector and rearrange how you want them to be.
Note that most printer controller boards have the GND of all the endstops connected, so technically you don't need the black wire at all. I make my own extension cables (from 4 wire cable) where the brown and black are connected at the sensor side and a single white wire is used for the Z-min endstop.


Anycubic Chiron does not print correctly

It is impossible to give a definitive answer without photographic evidence, since your description of the problem does not give enough information. The most common causes of "circular objects not printing correctly" are loose belts and loose grub screws on the belt drive pulleys.

However, you should note that the printer's firmware will not allow the print head to be moved outside the defined maximum printing area under software (g-code) control. This will cause large objects to be truncated if they extend outside of the defined maximum printing area, and I suspect that this is what is happening.


You could still get heat creep with a Bowden tube.  It has different characteristics.  Instead of jamming up in the direct drive, the filament can melt too far upwards into the heat break where it can refreeze and jam.  The characteristic, if you can pull out the filament, is widened filament extending into the heat break.
See Air printing/jamming midway through raft creation
and
What are ways to avoid heat creep?
Adding fans to an enclosure improves the temperature control in the enclosure.


For an easy test, try manually pulling the filament through the U-loop of guide tube. How hard is it to pull through? It should only take 1-2 lbs of tension at most.

Then do a "tug test" on the extruder. Start it loading and grab the filament by hand to try to stop it from extruding. The Replicator 1/2/2x extruder style can typically pull ~8-10 lbs of tension and it should be fairly difficult to stop the filament. When you do stop the filament, you should hear clicking/thumping from the stepper stalling, NOT quiet grinding as the drive gear chews through the filament. If the grip slips rather than stalls, your extruder hardware needs to be tuned or replaced.

There are three common causes of excessive feed tube drag:

Use of polyethylene tubing instead of PTFE -- this makes a shockingly large difference in drag friction. You can use a heat gun or torch (outside!!) to tell the difference between PE and PTFE. PE will soften quickly and then melt fairly easily, whereas PTFE will simply go clear and eventually char without melting. Nylon is also sometimes used for feed tubes with acceptable results, but if you have any suspicion about the tube material, just buy new PTFE tubes from a reputable vendor like McMaster.
Too many loops/curves in the tube. Total drag friction is an exponential function of the total amount of curvature in the tube. You should have one good U-loop, no spirals or floppy zig-zags.
Excessive friction on the spool rotation. Any spool back-tension gets greatly magnified through the feed tube per the capstan equation. This can be caused by a bad spool holder, or if the filament is knotted on the spool due to letting the end of the spool loose during handling.


Should I comment out the code for what I am not testing when loading the test firmware for Ramps 1.4?

There's no reason to comment anything out. It will work just fine without any modification, even if you're just testing a single motor. That said, I don't see the value of this "test firmware" over just installing Marlin.


How to achieve dimensional accuracy of printed parts

Unfortunately, different firmwares and different slicers require different calibration techniques! There's a lot of software-specific advice out there, like printing a single-wall calibration box and measuring the wall thickness. That's a good technique for Slic3r, but not for Simplify3D. It can be very confusing.

Here's the general outline of what you should do:

Rough calibration check for printer steps/mm. Do the values in your firmware settings make sense for your linear motion hardware? For example, you can calculate what the theoretical values SHOULD be based on belt pitch and pulley tooth count. Print something moderately big (~100-200mm) and check if it's +/-1-2%. If it's off by more than that, your steps/mm is probably wrong.
Check for mechanical backlash using a backlash-checking print like this one: http://www.thingiverse.com/thing:252490 Tighten belts and perform other printer-specific tuning required to eliminate backlash. Backlash will throw off other calibration steps, so make sure there's no slop!
Follow the recommended extrusion volume calibration steps for your slicer. This starts with measuring your filament diameter with calipers and inputting that into your slicer. And then you will usually either "print a single-walled box and measure the thickness" or "print a series of 100% infill calibration boxes and adjust the extrusion multiplier to the largest value that looks good without bulging." By measuring filament diameter and then adjusting an extrusion calibration setting in the slicer, you will be able to measure future filament and prints will come out right. Giving the slicer fake diameter values will force you to recalibrate every time the diameter changes. Note that you must redo this calibration for each FILAMENT MATERIAL and EXTRUDER DESIGN. Different material/extruder pairs will have different bite depths and effective drive diameter.
Precision calibration check by printing a variety of object sizes and PLOTTING "desired size" as X and "actual size" as Y. Then find a linear fit equation, y=mx+b. (Do this separately for your printer's X, Y, and Z axes.) The value "m" is your scale error. You can use your slicer object scaling to fix this. For example, ABS usually requires 100.3-101% scaling to account for shrinkage. If you have scale error with a low-shrinkage material like PLA, you can adjust your firmware's steps/mm value to compensate. The value "b" is your fixed width error. Assuming you don't have backlash, this is usually caused by the small amount that molten plastic bulges out to the sides, or by extrusion volume calibration error. You can improve this by fine-tuning your extrusion volume. Many slicers also have "horizontal/XY size compensation" settings that you can use to shrink/expand the part by b/2 to correct the fixed width error. Any residual fixed-width error that you cannot correct with slicer settings should be added as a tolerance in your part models.

If you follow these steps, you should get +/-0.1mm or better dimensional precision on your prints.*

*Deltas not included. That's a whole other ball of wax.


Printer goes beyond the bed when auto leveling

I don't know how your firmware load handles G29 ,but here's a guess, based on information at the  reprap wiki .  Try using FBLR to force the travel limits.

  Parameters

  P Set the size of the grid that will be probed (P x P
  points). Not supported by non-linear delta printer bed leveling.
  Example: G29 P4 S Set the XY travel speed between probe points (in
  units/min)
  D Dry-Run mode. Just evaluate the bed Topology - Don't
  apply or clean the rotation Matrix. Useful to check the topology after
  a first run of G29.
  V Set the verbose level (0-4). Example: G29 V3
  T
  Generate a Bed Topology Report. Example: G29 P5 T for a detailed
  report. This is useful for manual bed leveling and finding flaws in
  the bed (to assist with part placement). Not supported by non-linear
  delta printer bed leveling.
  F Set the Front limit of the probing grid
  B Set the Back limit of the probing grid.
     L Set the Left limit of the
  probing grid
  R Set the Right limit of the probing grid


Recommended settings for ColorFabb Copperfill Filaments on a 0.25 mm Nozzle?

It looks like a problem with feeding filament. It could be good to know if you did try such big printouts before but even if - from your picture it looks like on far end there is too less filament but on near end it's too much of it (because of 110%). And near the big circle it looks better even on far end. And there are "waves" close to big circle.

How is that possible?
Assuming that your extruder works well it might be caused by bending bowden tube. If your filament is not slick enough - in some settings (positions/arrangements) of bowden it might create enough friction so it doesn't flow with proper rate. It might be also caused if your bowden tube was bent too much (broken).

To be sure please try to print 4 smaller (5 cm in diam) circles on bed's corners and the one in the center. Just one layer of course.

How to fix the issue?
In my opinion you could try to slow down whole printout. Try to print such big circle with 30% of regular speed. I'm pretty sure you'll get proper results.

Try to check if filament goes smoothly thought the tube. Check if it has proper inner diameter. You can try to clean up a tube inside if it's not perfect clean or change a tube to new one. I know it was probably ok for recent filaments but maybe this one is more "demanding" ;)


Is it possible to use an aftermarket controller on a MakerBot?

You can put pretty much any controller in pretty much any printer, with a few noteworthy details you need to keep in mind for a Replicator 1.

Makerbots use thermocouples. Most RepRap style 3d printers use thermistors. So you would need to replace the extruder temp sensors, or choose a new controller with thermocouple support.
Makerbots use 24v heaters and fans and PSUs. Most RepRap style 3d printers run on 12v (although this is slowly changing because 24v is better for performance and safety.) You can either pick a new controller that is known to be compatible with 24v, or replace all 24v-rated components with equivalent 12v-rated components.
The existing heatbed thermistor circuit is probably not the same kind of circuit that your new controller will expect. Older Makerbots use a small voltage divider circuit on the HBP PCB to convert the thermistor resistance to a voltage signal, whereas RepRap style controllers typically have this circuit on the mainboard and thus need only a simple thermistor hookup. You could add a new thermistor, or modify the existing circuit, or get an entirely new heatbed.
The existing endstops are full +5v,GND,Signal style mechanical switches with debounce capacitors and LED indicators. These should be compatible with most controller boards given proper firmware setting, but you may need to do some creative wiring if there isn't a suitable three-pin endstop port on your chosen board.
The LCD and 5-button panel will not work with other boards. You'll need to replace that or just run a remote host via USB.
Connectors may be different, of course. That's always an issue with any board swap.
You will need to export RepRap style gcode instead of .x3g files. Makerware/Desktop can export gcode but there may be some minor differences in Mcode assignments from what most RepRap style firmware will expect. I couldn't tell you offhand whether this will work, but to be safe, it would probably be best to use a more traditional RepRap slicer (Slic3r, Cura) or Simplify3D.

So that's a healthy to-do list. At a certain point you're practically building a new printer. But there is a significantly easier approach than installing a RepRap style controller: replace the dead Makerbot Mightyboard with a compatible community-designed Sailfish board like the Azteeg x3 by Panucatt or new CloneBoard Mini by Carl Raffle. Or, if you're ok with Chinese sourcing, a FlashForge Mightyboard will be a near 100% drop-fit replacement for your Makerbot Mightyboard. Any of these options will give you fresh new electronics with minimal hardware changes in the rest of the printer.

Either way is fine and you'll end up with a working printer. Using another Sailfish board will certainly be easier, if you don't object to staying within the Sailfish/x3g toolchain and Makerbot/Clone parts ecosystem. Makerbot does have a very bad community reputation these days, but it's important to remember that the Replicator 1 Dual is a completely open-source machine from the "pre-evil" days, and compatible spare parts are widely available from literally dozens of vendors. The Rep1-derived Makerbots and Clones collectively comprise the most popular single "flavor" of 3d printer in the world (totaling as much as perhaps a quarter of all consumer/hobbyist 3d printers sold to date) and many/most of the spare parts for Replicator 2/2x's and clones will also fit in a genuine Rep1.


Filament material for chemical application

There are two issues you have here, one is temperature stability and the other is chemical reactivity of plastics. I can't help you with the chemistry side, but I can help with the temperature.
Application 1 (Temp < 40 °C)
Any FDM plastic will perform reasonably well under these temperatures. I would suggest trying a Nylon, PETG or a PolyCarbonate filament as I know these are more resistant to acids than PLA or ABS. As far as strength of the parts, all FDM plastics will work well
Application 2 (Temp > 180 °C)
This temperature range is above the glass transition temperature of the PLA, ABS, PETG and Nylon are all well below 180 °C and therefore aren't worth considering. Your best option is PolyCarbonate, or PolyCarbonate-ABS which are both fairly high (roughly 140-150 °C). However, are both below your minimum temperature threshold.
My conclusion is to try a polycarbonate sample and see how it reacts to the chemicals you're working with, though it doesn't look hopeful.
For Chemical reactivity, I did some Google-fu and found a few links that look helpful for PolyCarbonate:

Chemical resistance polycarbonate

Polycarbonate Chemical Compatibility Chart


My personal technique for removing prints (particularly larger prints) is not to flex the mat at all. Instead, I wait until it's cool and then work the spatula under an edge and move it under the model to basically peel it from the mat.

Smaller prints usually pop right off if I start with this technique from one end.

Surface area on the bed (for a single part) is most important to how much work is involved. For example, a raft or brim will greatly increase the surface area.  The spatula is long enough that usually I can reach everywhere under the model so eventually it will pop free. I might have to work around the model a bit before it reaches this point.


Progressively worse relative size error at smaller absolute sizes

You should not look at the relative dimensional differences, you should be looking at the absolute differences. Multiplying the undersized dimensions in percentage with the cylinder diameter gives you a value of 0.4  mm for each cylinder give or take a few hundreds. So, basically your printer works very consistent it is just suffering from a systematic offset.

Basically, the printing process needs to
adjust the X-Y dimensions to compensate for plastic flow effects. An option or setting in Ultimaker Cura to counteract this is called Horizontal Expansion. Slic3r and Simplify3d have similar settings. In Slic3r it is called XY size compensation.


Ender 3 displaying wrong temperatures for hotend and bed

I got my printer fixed and am posting steps I took for people with similar problems in the future.

Initial problem:

After I replaced my entire heating unit and reconnected the wires, my printer started to read about 135/185 °C for the nozzle and bed at room temperature. It gives the "Heating failed, printer halted, please reset" error when I tried to heat the hot end and bed.

Troubleshooting steps:

Checked the resistance of the thermistors. Both the hot end and bed were about 100k.
Reflashed Marlin with different thermistor settings. Only the static (dummy) ones worked (reading a static value of 25/100 °C). All the other settings were giving very high readings at room temperature.
Replaced the mainboard. This fixed the bed reading but hot end was still not working. Checked the hot end thermistor again at this point and couldn't get any values, which suggests the thermistor wire was broken somewhere.
Replaced the hot end thermistor and that fixed all the issues.

So what I think happened was that I messed up the board when I was reconnecting the heating unit. Then at some point after I first measured the thermistor resistance, the hot end thermistor broke. Replaced the thermistor and that solved the issue.


It is really strange that although you increased the steps per mm, the amount extruded was less. I can think of two possible explanations:

You are extruding too quickly, at a rate at which the extruder can't keep up melting the filament fast enough, causing the filament to slip or the extruder to miss steps: try lowering the feedrate (a feedrate like 100mm/min is typical for 1.75mm filament) and make sure that the temperature is appropriate to your filament.
You are in absolute coordinate mode, and when you try to extrude 100mm it actually extrudes a different amount (based on the previous "position" of the extruder). Enter relative coordinate mode using G91.


Extruder spins for a few seconds after layer changes

Doing some googling, it looks like the BEFORE_LAYER_CHANGE comment in the G-code and stuff that follow come from the before_layer_gcode setting in your PrusaSlicer profile. Somehow, G92 E0.0 got in there. Remove it and the problem should go away.


How to tell machine how far travel limits without switches

Since 3D printers works with coodinates and the gcode generator requires the origin point and bed shape and bed size. knowing this your programs never will be out of the printing area.

My printer has a printing area of 16.5 x 16.5 cm, so I set this parameter to CURA, Slic3r and 3dsimplify and I can't generate the gcode if the part does not fit on the bed. So I print parts with 15cm maximum

Also the firmware has this limits to 16cm, the 0.5 cm is just for safety

Of course if I send a command with pronterface or any other gbrl controler I can go over the limits due the X0Y0 could be out of position (offset), but if you respect the origin point and don't try to go over the limits by yourself the machine will be ok.


In your case, since linear advance makes the issue disappear, the reason of the thinner lines is the same as explained in the link you provided:

The section (2) simply is very long because you probably have a Bowden setup which takes more than the length of the middle section to recover. However it does recover, see the first line (k=0) in the first image.
At higher (constant) speed the flowrate decreases further due to pressure in the nozzle causing a reduced supply of filament, but this effect cannot be corrected by linear advance because linear advance assumes a linear relationship between pressure in the nozzle and extrusion.


How to remove internal part of a hex grid

I ended up finding a reasonable solution myself:

Basically, I diffed two identical, non-hollow geometries, in which the first one had the cells larger than they needed to be (so overlapping with others), and the second one had them exactly of the right dimension:

difference() {
  base_geometry(range, angle, infill, extra_padding = 2);
  base_geometry(range, angle, infill, extra_padding = 0);
}

This way the only portion of the solid remaining was the extra_padding on the outer edges of the geometry.


What is causing these strings in the overhangs?

While this looks a lot like stringing, it's not what I would call stringing. I usually reserve that term for material that should never have left the nozzle to begin with, due to insufficient or missing retraction or excessive compression of the filament between the extruder and the nozzle. The "strings" you've shown look like desired wall extrusions that did not adhere to the adjacent walls in the same layer or to the previous layer.

This is common when printing concave perimeters that are overhanging, due to a combination of minimal-to-no contact with previous layer and acceleration of the nozzle away from the previous wall in the current layer. Sometimes under-extrusion can also be a factor.

You can often mitigate this by:

using thinner layers (for the whole print, or "adaptive layer height" that will dynamically adjust as needed). For a given wall slope (fixed rise over run), this will reduce the "rise", and thereby place the walls of the next layer such that they overlap more with the previous layer. Sometimes this makes the difference as to whether they overlap at all.
increasing hotend temperature. This will improve bonding with adjacent wall and with previous layer, if there's any contact with it.
decreasing print speed, especially for outer walls. This will reduce the effect of the nozzle pulling the wall away from the adjacent wall it's supposed to bond to, and will also deliver more heat to the adjacent wall and previous layer wall you want to bond to.

All three of these will also help if under-extrusion is part of the underlying cause.

If you can't get any of this to work, using supports is always an option, but spherical (as opposed to flattened) domes generally "shouldn't" need support to print.


Anet A8 extruder is clicking and not extruding

There are a number of unanswered questions which may serve as a guideline to narrow down a solution.

Instead of attempting a new print, consider to remove the filament again. Shine a light from below and look into the barrel of the extruder to determine if you can see light. If this is mechanically impractical, move to next option.

Manually feed the filament into the extruder. Use the panel to advance the filament rather than creating a print. Does the filament feed properly?

If yes, the problem is not in the extruder system, nor the heat block or hot end. You said you re-leveled the bed. Double check that the nozzle is not being blocked by the bed, preventing filament from extruding.

If the filament does not feed properly, you may not have completely cleared the heat break, hot end, or nozzle. If you can get or have nylon filament in the correct size, perform a nylon cleaning operation. This involves removing the existing filament, raising the nozzle temperature to 240°C while pushing nylon through. You have to be able to manually force the filament through until you see only clean nylon from the nozzle.

I have had to push nylon in at the correct temperature, then pull it back out without any extrusion due to the depth of the blockage.

After you've pushed as much as you can to get clean nylon (or none), cool the hot end to descend below 140°C. After a moment or two, set the temperature to 140°C and forcibly remove the filament from the upper portion of your assembly. It may require pliers and substantial force to get this out.

Repeat the heating, extrusion (or attempts), removal until you get clean nylon from the nozzle and clean nylon at the tip of the removed filament.

Only just today, I had to clear my nozzle using this method, but I was unable to get a reasonable extrusion of clean nylon. I have a 0.4 mm nozzle drill and applied that to the tip of the nozzle, carefully.

I found a burned on segment by this additional step and succeeding nylon cleanings went well and my nozzle is printing cleanly again.

If you don't have nylon, you can perform similar cleanings (called cold pulls) with ABS or PLA.


Issue with 3D printer making super thin layers

You need to level you bed.  Thin prints happen when the extruder is too low and is printing too close to the bed.

Download the following test codes from this address:

https://www.chepclub.com/bed-level.html

1) The first code is the most important you will want to run moves the extruder to five points on your board - Front Left and Right, Back Left and Right, and Center.  Using a folded piece of paper - I use a business card - drag the paper under extruder of each of the four corners.  You want to make sure you get a bit of drag when pulling out the paper/card.  If you feel have enough of a gap that you can run put the paper/card under the extruder and that you feel a bit of tug when pulling it out.  It runs the middle last - if you are having issue with the drag, adjust all four corners slowly until it is right.

2) The second runs the extruder in a square pattern on your board.  You simply want to run your finger of the print - if it sticks to the bed, you are good - if it doesn't, adjust your corners up and keep testing.


As @fred_dot_u mentioned above, keychains are a simple, personalized item to make.  In terms of interesting projects, things that I found intriguing when I first encountered 3D printing were objects that could not be made by other means, such as those "geared bearings" (Google: geared bearings 3d print).  Given the popularity of figet spinners a while back, they could be an interesting item.   A captive ball in a box, or three joined rings, can also be set up as a 3D print, and could have the same effect, while being easier for the kids to design.

EDIT:  Some links to versions of items along the above lines.  Thingiverse tends to slowly break links, though, so these might not last:

Geared Bearing
Captive Ball
Three Rings
Triple Gear
Self-aligning Bushing Keychain


Creality CR-10 problems with extrusion while printing

Clearly you're having an extrusion problem. Extrusion problems usually come either from a clogged nozzle (as @Adam S. said) or from the extruder it self. To determine where the problem is located I would first do a flow rate test using this. When doing this test you can determine if the extruder is grinding the filament or if it's not grabbing it too much. After the calibration of the flowrate you can be certain that the printer is (by .gcode) pushing the correct amount of filament. If the problem persist I would first do an unclogging (since it's cheaper than the following option) using something like this.

If both previous options do not solve the problem, I would highly recommend you to by a mk-8 like metal extruder. After a while, the plastic one that comes with the printer loses force and you'll lose steps. Personally, I had a similar problem where the first layer was printed in a droplet pattern and was solved by changing the extruder to a metal one.

Try these options and if the problem persist you could upload some pictures of the first layer or a video. Other possibilities I think of are that the filament is having trouble passing through the Bowden tube or maybe you'll have to reasemble the hotend.


What do I need to go along with my new SLA 3D printer?

Safety Gear
Gloves, you want to wear them whenever handling any resin. Single-use gloves are best - dispose of them after use. Consider them contaminated after touching anything in contact with resin and toss them before handling anything that shall not get in contact with resin. That includes door handles.
A good idea is to also wear eye protection, as resin in the eyes could destroy them.
While a dust mask might not be strictly necessary, it could reduce your exposure to the fumes of resin. Some resin fumes are known to create hypersensitivity.
It is also a good idea to put the printer into a dedicated workspace that is well ventilated and not your primary living space. I strongly recommend reading both Best way to deal with Resin Printers in your living space and Safe way of disposing resin
Post-Processing Station
You may want to build a post-processing station. Most pieces can be sourced in any home depot store or made from household items, so I don't recommend specific brands but the requirements.
Washing Station
A typical post-processing station consists of at least 2 vats large enough to submerge your print volume in, so you can wash off your print in the first and then wash it with fresh liquid in the second. The typical liquids for cleaning are isopropyl alcohol and sometimes technical alcohol. Some resins demand special liquids that are specific to the type of resin. Best, the washing vats have securely sealing lids. Glass is preferably as it is easy to clean.
To use the least amount of cleaning liquid, you might want to have a pair of needle spray bottles - one for each bath. Label them!
To avoid spillage and ruining tables, a plastic table cloth can be a good addition. Fold it with the contaminated side onto itself for storage. A different solution would be to put the cleaning station onto a ceramic or steel surface, which can be easily cleaned after use.
Curing Station/Chamber
The next step is curing the print under direct exposure to a UV light source, somewhat akin to how gel nails are hardened. Sometimes the sun is enough.
Since the resin residue from washing is now in the isopropyl alcohol (or other washing liquid), treat it as chemical waste. To reduce the waste of material, flock out the resin in it by exposing the liquid to the UV light and filter the result. The result is Isopropyl Alcohol with some remaining contaminants, which can be used again for the first rinsing step.
Other Tools
Besides cleaning and curing the print, you need to remove the print from the plate, so you need a spatula or scraper, which is reserved only for your SLA printer. Never use it on the build platform of your FDM printers and consider it contaminated with uncured resin after use. Best cure residue on it in the UV chamber and then physically chip off the hardened resin before handling it without gloves again.
Similarly, a tool to stir the resin and remove flakes is often used, and some makers have special spatulas to clean the vat. Clean them well after use.
You will want to have some nice snippets to remove the support structures at some spots and some pliers to break them free - safety first.
Needle files and sanding paper for cleanup where the support stuck are a given.
Resin Recovery
Since the resin in the trays might harden over time, you'll want to have some sort of rig to hold the vat at a tilted angle upside down so it can flow out, back into the resin bottle. A cover might also help to reduce exposure and allow short time storage in the machine. Thingieverse has a couple of solutions for lids, pouring and filtering stations as well as other accessories. Look for those that fit your printer.
The Resin should be stored in airtight and light-blocking bottles. As an extra security measure, you should store the resin in a closed cupboard to prevent light exposure through not totally opaque bottles.
More on Re-using resin can be found here
Further Reading/watching

Angus/Makers Muse on 3D printing safety
A rather good guide regarding Resin 3D printing


Software for adding supports to 3D printed miniatures in STL file

I don't think you'll find automated software to create supports "the way I want them to look."  So...

It might be worth investigating the "Advanced Properties" of Cura to see how thin, and thinly spaced, you can set its support walls to be.  I know there are settings for reducing the thickness at the top of the support, as well as some sort of "top gap" setting, for just the kind of problem you're dealing with.


Bed is leveled and not warped but still uneven printing?

Be sure that you have no previous bed meshes saved and automatically applied: use the commands M502, M500.
Once you have done that, try this technique:

It's about using a ruler to detect areas which are lower, and then use stickers below the glass to thicken those areas only, resulting in a much flatter surface.
If you don't want to use the blue tape (which will worsen the heat transfer, but not so much after all) you could use 0.3 mm silicone thermal tape, which is more heat conductive but it's also quite thicker than blue tape.
This other alternative consists of flattening the plate itself, but it's inevitably performed when cold, while the tape technique above can be performed at the desired temperature (since the warping may not be constant).


Cura confused as to what's touching the buildplate?

The up- or down-ness of a part is its Z-orientation, which is specified in STL. It looks like whoever published that STL file published it upside down, requiring you to flip the part or rotate it by 180. You can flip it in Cura as you've done or leave a comment to the author of the STL that the part is upside down.  However, the author may not know how to fix this because low-end modeling tools typically do not have the capability of flipping a model. In these cases, using another tool such as Cura or Slicer can generate a right-side up model. Cura seems to like generating AMF files, so I use Slicer to generate STL files for upside down models. Once you correct the STL file, you'll be able to import the model directly into Cura right-side up.


How neodymium magnet affect (if any) on extruder motor

The best way to know is placing the magnet on the shaft; if you see that motor starts shaking or stops this mean that you affects the motor operation, but I think if any magnet interference can be deprecated due internal coils of the motor during operation.

The motor works with some coils in the rotor and some magnets in the stator (motor frame). But the shaft is to far from the coils to be affected for the magnetism of one small neodimiun magnet which needs at least 7mm to trap another small metal objet or for induction sensing and 2mm as maximum for creating electrical flows (generation); this values are afected if the magnet is placed over other metal part reducing his atraction field, and the armor is too big for an small magnet 8x3mm.

You can attach some indicator with a double sided adhesive tape (3M) if still are worried about affecting your extruder.

If your motor extruder is heating during extended usage periods you should adjust the motor current, for example: you motors is rated 0.5A you should calibarte the current for 0.48A or 0.45; this could reduce the torque force of the motor by a little. Or maybe the current current :D is calibrated above 0.5A thats way you are getting over heating.


That particular font is Sarina Regular and is part of the Google Fonts collection. Just Google "connected handwritten fonts" to find more. Kimberly Geswein does a good selection of handwritten fonts. A lot of them are constant width, but most are unconnected.


Identifying the plastic type of an unknown spool of filament or recyclable waste

ABS dissolves in acetone, you could try clipping a small section and leave it in some acetone for a few minutes and if it begins to dissolve it's safe to assume that it's ABS, if not then you'll know that it's not.

This won't confirm that it is PLA, only whether it's ABS or not.


Different Probe Z offset for G28 and G29

I'm answering my own question here.

The Issue was that I set Z_MIN_POS to -2.0 I guess these 2 mm were subtracted from G28 but not from G29.

I don't know wether this is expected behaviour but changing Z_MIN_POS back to 0 fixed the issue for me.


Writing G-code: Audible Alert at end of print


How to choose a right 3D printer filament type?

Determine what properties you need the filament to have.
There are a very wide variety of filaments because they all have somewhat different properties.  You need to determine what properties you need your final print to possess.  For instance, ABS can be smoothed used acetone and PLA is biodegradable. More exotic filaments could be conductive or be extremely flexible. Do not neglect to consider safety of the plastic in your application. A full list of properties is too broad for an appropriate answer from this site.

Determine what you printer is designed to handle.
Most printers can handle PLA and ABS with little issue but higher temperatures are required to use some materials such as nylon and polycarbonate.  Determine beforehand what your printer is designed to handle.  This includes determining whether you have and appropriate heated bed or other accessories.

Determine what you can afford.
Printing not only requires the cost of the weight of filament in the final print but all of the support structures and misprints you produce. Not only should you look for inexpensive filaments, but you should look for ones that are good enough quality you don't waste time and money fighting problems with the raw material.

All in all, this will vary case by case.  I would recommend that you start with PLA or ABS as they are common and relatively easy to work with but that you do your own research into what each individual filament type has to offer..


Kinda, sort of, but not really. I'll look at the A4988 (datasheet).

The motor pins are connected by diodes to ground and Vbb (the motor suppply voltage). Essentially, they act as a bridge rectifier making any back EMF or inductive spikes appear (rectified) on Vbb. If you were to suddenly power down the driver this could cause a rather large spike on Vbb.

According to the datasheet, there is a 40 V Zener on Vbb which will clamp the voltage to that level. (Another popular stepper driver, the DRV8825, does not appear to have this Zener - always check your datasheet!)

So, yes, there is inductive kickback protection. However, it only clamps the voltage to 40 V. Depending on the rest of your circuit, this could be quite damaging.

The datasheet recommends that a 100 μF capacitor be placed on Vbb. If you are driving a typical stepper motor with 2 A and 4 mH coil inductance, the energy stored in the coil is 8 mJ. This energy is only enough to take the capacitor up from 12 V to ~17.5 V, so if you have a large enough capacitor on your stepper driver (as you should!) then you're protected against inductive kickback.

Note that if you move the motors by hand then you can still build up a higher voltage on Vbb. I've heard anecdotes of people who damaged their printers like that.


Insulate hotend on Makerbot Smart Extruder

I recently wrapped a LOT of hot PLA around my print head and, as a result, had to remove the kapton tape and the fibreglass insulation that came with it.

I was reluctant to use fibreglass because of the tissue embedding hazard and the lung hazard (especially on what is effectively an indoor appliance) and kapton tape is very hard to find in Australia.

After some research, I wrapped the print head in 100% wool felt that I bought from a fabric store (be very careful, as most craft felt nowadays is either acrylic, polyester or a poly/wool blend) and then bound it all up with teflon thread tape (plumber's thread tape).

Cotton has a scorch temperature of 150 to 200°C, while wool won't scorch until 500 to 600°C, and the teflon tape can handle temperatures between 200 to 300°C.

Did it work? Well I can now put my finger on the outside of the tape after the element has been at 200°C for 10 minutes, and only feel a little warmth. The print head heats up twice as fast, and I can run my massively oversized print cooling fan at 40% rather than the 10% I could use before. There is no odor of anything cooking off either. Success!


I'm searching for a tool to generate 2D PDF of one side of my model

OpenSCAD has a great feature called projection which allows you to select a vertical location and effectively "cast a shadow" of the part. The projection becomes a 2D object scaled to the original model.

One can rotate, translate or otherwise transform the model prior to performing the projection function, in order to get the appropriate 2D drawing.

The resulting "model" is rendered using F6 and can be output as .DXF or .SVG as well as a number of other formats that might not be as useful to you.

EDIT: I've been recently using Onshape to create drawings from 3D models. It's also a free program, browser based which allows you to import your STL model (or other acceptable formats). Once imported, a drawing can be created with three-view and isometric, or you can edit to create only a single view. This can then be exported/downloaded as a PDF.

The screen capture image below is from a project I've recently created. The original STL file was imported and the result is quite clean.


If making your own caps ends up being the best solution, TPU (thermoplastic polyurethane) is probably your best bet. I don't have specific information on printed TPU filament and ozone, but TPU is widely regarded as one of the most chemical-resistant materials you can easily print with, and this page by Ozone Solutions rates polyurethane (no mention of specific types) A/Excellent described as:

  Ozone has no effect on these materials. They will last indefinitely.

Being at least slightly flexible, TPU will also yield a good seal without any additional gasket. You should probably choose an unpigmented "natural/clear" TPU filament in case the pigments do react.

It might (probably would) also work to coat an existing cap with polyurethane. I'm not sure how you'd best get it to adhere, but lightly sanding the plastic then using a spray in multiple coats is what I'd try first.


Do firmware updates affect print speeds?

I agree with @silver, but also wanted to point out that maybe the acceleration values on the old firmware you had were different from the default in TH3D R2.7.

The current settings can be retrieved using the M503 command, which should return the values from the eeprom:

Maximum Acceleration (units/s2):
M201 X1000 Y1000 Z100 E10000
Acceleration (units/s2): P R T
M204 P400.00 R1000.00 T1000.00

You can then lookup the default settings for your printer model and use M201 and M204 to set the new values. Then M500 to save the new settings to the EEPROM.


Over extruding and feeding gear is grinding Ender 3 pro

It sounds like a setting mismatch between your slicer settings and the physical printer configuration. Diagnostic and informational questions follow:

Can you provide more details of your machine configuration and your slicer settings?
Are you using the Creality Slicer?
Can you also provide more information about what you are attempting to print?
Are you printing a downloaded design or your own?
Have you printed successfully before? If so, the key question would be to ask what has changed.

There are a number of settings to check, but the first one that comes to mind is the filament diameter setting in the slicer. Secondary to that would be the flow percent. Check the diameter of your filament versus the setting in the slicer. The grinding of the gear makes me think that the physical filament diameter is larger than the slicer setting.  This could explain extruding too much material and producing "blobs" and also the grinding.


Five top layers should normally be more than enough to create a seamless top layer.

Indeed, PETG prints a little differently than PLA. It requires a higher hot end temperature, less part cooling (to improve sticking to previous layers), a higher build plate temperature and usually care in choosing the right initial layer height. Once the printer  needs to create the top surface layers, too much temperature, too less cooling and too low of an infill percentage can cause the top bridging over the infill to fail. Your settings seem to be fine except for the low percentage of infill, 15% is very low.

Other possible causes could be under-extrusion and too fast printing, but in this case the low infill percentage is probably the main reason. To get a better top layer you could first try to increase the infill percentage. If you go to 20 or 30 % infill, you would only marginally "waste" filament. More filament and time is wasted when whole prints fail as of a bad top layer.


Is it possible to run 2 Ender 3's off one power supply?

The heated bed alone draws 220 W of 24 V power, so I'm going to say no, you shouldn't attempt to run two Ender 3 machines from a single power supply.
Instead, because the whole machine only draws about 3.5 A at 115 V (or half that at 230 V), you should consider installing a power strip or (better) a small UPS to both power both machines from your existing outlet(s) and also protect the machines from power surges and short power interruptions.  You won't overload your outlets, and you won't risk burning out a power supply by drawing twice the power it's built to provide.


3D printer ends print by sinking in to it and getting stuck

As can be seen from the G-code file, the head is instructed to travel to x=0, y=0 (G28 X0 Y0 is actually a homing instruction to home the head and label the position with zero X and zero Y). After that it powers off the motors (M84).

From your picture, it looks like the head digs in the print without moving to the home position, so G28 X0 Y0  is not working (although you mention it tries to move while digging in?!?). That is strange as there is no instruction to lower the head. Please alter G28 to G0 so that it reads:

G0 X0 Y0

(or G1 X0 Y0 which does work and will instruct the head to move).

The digging into the print could be explained by the weight of the head/carriage that cannot be held when the steppers are not powered anymore (as instructed by M84). When the nozzle is hot, the nozzle will then dig into your print.

Edit:

Now that I see your comment on another answer, your proprietary software may produce different G-code than Cura does, this could imply that your printer does not use a "standard" G-code interpreter or does not implement all G-codes.


Heated Bed vs Heated enclosure for large scale printer

I tend to agree with Davo, that you might want both. But I'd probably try the enclosure first. My printer is about 1200 by 400. I looked at options, and found some difficult trade-offs:

First, the big heatbed approach:

as you know, getting a single heatbed that big will be expensive (and if it ever breaks or fails, you have to replace it all).
a big heatbed also draws far more power than a RAMPS board can switch, so you'll have to use the on-board control to control a power relay (solid state or mechanical).
a big heatbed will also waste a great deal of power when you're doing small things.

Second, the heated enclosure approach:

more costly to heat up at the beginning, but if insulated it may be cheaper for long prints (with a bed that large, your prints might take really long, too) because it can retain the heat better.
if you keep the air circulating inside, you'll get much more uniform heat, rather than hot first layers and cooler higher layers.
consider the effect of the heat on all the other components: motors, electronics, pre-heating the fibers, thinning any lubricants,....
you could save some heating cost and time by providing a way to shrink the space to be heated: perhaps just a partition you can insert when doing smaller prints. It wouldn't have to be nearly airtight to make a big difference.

A third option is several small heatbeds:

this lets you turn on just the ones you need for any given print
still expensive, but cheaper than one big one, especially when any of them fails.
there will be uneven heat at the seams, but if you place the boards tight together I doubt it's enough to matter. You could also carefully trim the boards' edges to get the spacing closer to uniform.
temperature regulation will be tricky. If you want to support a temperature sensor for each board, you'll have to start hacking at the control software, because (as far as I can tell) there's no provision for multiple heaters. Probably easier to create a completely separate unit with a big power supply, and a simple thermostat for each of the beds, that you just set manually before starting a print.

Overall, I think the heated enclosure may be best. I like the hair dryer idea or heat gun idea, of course you'll need a little extra circuitry to switch it, but you can use the usual software for temperature regulation by installing thermistor or thermocouple in the case (just be careful about circulating the air well enough to avoid "hot spots").

You may want to add an extra cutoff to protect against runaway heating -- I had that happen once when a thermistor literally fell out of the mounting hole in the hotend. Something like https://www.grainger.com/product/SUPCO-Thermostat-407L11.

Let us know how it turns out.


What part is this? Circular threading spool gear, about 10 mm diameter

This is a timing belt pulley.

Specifically, is a GT2 timing pulley, 2 mm pitch (between teeth), 6 mm wide. The drive diameter is measured by the number of teeth (16 in this case) , the shaft diameter (bore) is measured in mm.

The 'GT2' part refers to the tooth profile, some other examples are shown half way down this page.


It's a question of what you want to use the belt for.
All Belts are subject to stress as they run around the motor and idlers and gears and bend. They will get eaten as they are subject to friction against parts, they will stretch as they are subject to tension. All this applies some sort of stress or another on the belt. Anything that is subject to stress wears. And as it wears, it will fail. The question is just: What is your life expectancy? The lifetime expectancy is again dependant on how the belt is used, so usage dictates lifetime of the belt.
Each belt type has an application it is designed for. A bending radius that is to be kept at, a gear it is to be used with, a load it is expected to move, a tension it is expected to uphold, and a lifetime it is expected to serve.
Let's take a short look at some rough ideas what
a soft rubber belt without additions
This is usually a bad choice for printers, but can occasionally be in very cheap kits. This kind of belt has applications. It is for really low loads, it can work tight bends for a long time and provides superb self-tensioning with just a very short tensioning device. On the other side, most rubbers don't take heat well, stretches a lot, wear fast and can only move a light load. If it rubs against a standing object, it squeaks horribly.
a medium hard, somewhat elastic belt reinforced with fibers
The standard belt we often get with printer kits. the fibers lessen the material's stretching ability while offering still some self-tensioning (depending on the fibers). These properties allow to move medium loads yet harder material demands slightly larger bend diameters (not too much, but measurable!). When the piece gets friction against a standing surface the sound will be not that horrible, but the harder rubber might start to shave off, break teeth and destroy the belt after some time. The typical reinforcing is done with cloth, usually cotton, so there are some limits to how much they can take.
reinforcing with aramid fibers
Some fibers are better than others for our applications because of how they stretch and reinforce it. Aramid fibers, for example, are better than cloth. Some consider them as impossible to wear out with the tension in 3D Printing applications alone, but that is not entirely the case. They still stretch under larger loads or on longer lengths enough that it can be a problem (or become one). They also can still be shredded with friction (and heat). For a professional machine, the expected lifetime is quite nice. They are though, but only as good as the rubber used and if properly installed. There are also generally two types: long fibers and short fibers. Long fibers have a somewhat even stretching behavior, while short fibers have totally different stretching behavior. The latter type is looked at in scholarly articles like Yin, Zhou, Lou et al.
a hard belt reinforced with fibers
Let's take... Uhm... a toothed belt from a car. I believe some of these are aramid-reinforced, old ones are on cloth cores, most modern ones I know are steel reinforced. It is somewhat hard. By design, it is made to withstand a strong tension at high speeds. It needs somewhat big bending radii for the hard rubber, but that is easily given by the gears and the large teeth don't break easily. Over the lifetime it will slowly stretch due to the temperature it will encounter, till at some point it gets too loose or looses too many teeth as the parameters don't match up with the teeth anymore and they get ground away. It is made to deliver high torque and could move - if something similar was used on a printer-like machine (like a large CNC), a heavy load for a long time, but the machine needs to be made accordingly.
steel reinforced belt
Steel is going stiffer. Steel reinforcements usually get the stretching parameter to a bare minimum at the cost of increasing their minimum bend and added weight. They can be used to move very heavy loads without the belt starting to slack as it simply can't stretch to give slack on the underside of the belt loop when forces are applied. Steel belts are pretty much Heavy Duty. If you can work with the bending radii belonging to them (as said, usually a little bigger than a similar fiber-reinforced one), you could make use of these properties, for example in a CNC Router with a full spindle or when moving very heavy tool heads.
carbonfiber reinforced
And then there is the super heavy-duty carbon fiber. One can barely stretch it (steel is less stretchy), making these belts super tough in the stretching compartment and granting an extremely long life under most conditions. In comparison to steel, they can work much tighter radii. Usually, they are coupled with urethanes to get a high wear resistance against abrasion. The biggest downside: their price.
Belt Materials
Silicone
Silicone is soft but high temperature resistant but dislikes abrasive forces.
Uretane
Urethanes are not the best to handle the heat, but they can handle abrasive forces. They also don't create dust in the same way as other rubbers.
Neoprene
The most interesting feature of neoprene belts is their reduced noise under work.


Getting hot air from the radiator is definitely wrong idea because of few reasons:

hot air can damage your fan (as they are usually not heatproof). Cold air cools the fan
cold air is denser so fan can suck more cold air than hot air so cooling is more efficient (fig A)
in terms of plug of radiator (with dust) it's much better to try to push cold air into plugged fan (fig C) than to suck the air from it (fig B). When flow is decreased there is higher possibility to damage the fan as it doesn't cool itself

Of course we are talking about 3D printers with small plastic fans. Please notice (almost) all fans construction: they are designed to get air from the top of the fan and push it to the bottom (this construction prevents damaging/plugging fan motor by dust)... and their mounting wholes (or clips) are usually... naturally suggesting to direct air to the heatsink)


What are the advantages and disadvantages of an all-metal hot end compared to one with a PTFE heat break?

This is a good question to make a comparison table. All-metal hotends Vs. PTFE liner hotends.

All metal:

Works well for high (+250ºC) temperatures filaments like nylon or PC.
No need to replace the PTFE liner (pretty obvious).
Retraction performs worse.
Plastic can get stuck to the inner walls. This can lead to clogging, more likely when changing from ABS to PLA (higher temp plastic to lower temp plastic).

PTFE liner hotend:

Limited working temperature. Above 250 PTFE will start to degrade.
PTFE tube needs to be replaced more or less often, depending on the use of your printer.
Retraction performs better.
Plastic is less likely to get stuck in inner wall (PTFE is very nonstick).
When using PTFE liner, the plastic is melted very close to the nozzle. Unlike other techniques, in FFF/FDM 3D printing this is more desirable. E.g. to avoid 'heat creep', for a better flow control and more accurate output dimension.

Of course there are more points to compare. Please comment to add any other useful point.


Ender 3 + SKR 1.4 + Marlin 2.0.x bugfix - what bed size/min/max positions should I use?

The Ender 3 has a printable area of 220x220x250 mm according to the specifications. So, there is nothing wrong. Sometimes heated beds are slightly larger than the actual print area. E.g. 235x235 mm or 310x310 mm. For centering the nozzle to the build plate, you should look into "How to center my prints on the build platform? (Re-calibrate homing offset)" or "Recalibrating Home-position.


Subtract of two STL files in Slic3r software

Given my limited familiarity with all the CAD tools that exist, I would fall back to something that I know does binary operations on volumes -- openScad.

One can create two objects, one from each of the two STL files, and subtract one from the other.  One can also compute intersections, unions, and other operations.

There are probably other programs that also do this, but openScad allows for doing in programmatically, so that once you have it right, you can update the objects without needing to redo the finicky part of the operations.

slic3r may do this, but I haven't seen such features in my multi-year use of slic3r for slicing.

When in doubt, IMO it is better to script something.  It is virtually never that I do something only once, especially in 3D printing where rapid prototype leads to rapid change and improvement.


Why are stepper motors used in 3D printers?

FDM 3D printers need to do repeatable moves. Servos might give better and more repeatable torque, but they don't give very precise movement without the need of an encoder system. This makes Steppers cheaper and easier adaptable in most cases, even though there are some printers that use different motor systems.

Note that different printers like SLS printer do use several simple motors, especially for the system putting down powder, and the tilting system in the new mSLA Prusa uses - afaik - a simple motor doing one rotation per tilting motion.


Prusa i3 mk3 step skipping and layer shifting

Long story short: Try to replace the stock power supply.

We connected UPS between the printer supply and the wall outlet and the skips reduced to one/two per print.
We replaced the supply with random old used Mean Well SP-320 (zero care about the power panic feature, just plain 24V connected) and voilà: reference design passed.
Also few more complex designs after supply switch are still flawless, so we hope that was the problem and it's fixed now.
This Q&A post is to help others to skip the major frustration and save some time.


I actually find it's not needed for PLA. I generally have it heated to 40 °C and use blue painters tape along with some hairspray (I prefer Tresemme as it smells gorgeous).

I've experimented with a glass bed, and Buildtak but I find blue painters tape is the key. I overlap the blue tape ends to the bed so it sticks, then spray the hairspray onto the tape. Also bed leveling is super important as are your print settings. What you want for the first layer is to have it essentially "pushing" into the bed. That way it gets good contact and wont curl up during the print, though it can be a challenge to get off later.

TL;DR for PLA you dont need a heated bed, its more about the surface and 1st layer height.


Carbon or glass fiber reinforced PLA likely has the strongest without deformation. PLA will snap before deforming.

Fiber reinforced ABS is also an option. ABS is stronger but will bend before breaking.

Both are hard on nozzles and may require a stainless steel nozzle.


Creality CR-10S Pro 3D printer heated bed turns off after first few layers: normal?

Cr-10 S Pro has an eco mode make sure it's not turned on because this will turn your bed off after the first few layers have printed.


Z-offset issues with Slic3r and Da Vinci Nano

Behavioral analysis
To find out what is actually wrong, let's do a simple series of test commands first: a G-code that homes the printhead, moves it up 100 mm (10 cm), then zeroes there, moves up 20 more and back to the new 0 at 100 mm above the bed. Make sure not a single offset is active anywhere when sending/loading the G-code as this is to test for the actual movement.
G28
G1 Z100
G92 Z0
G90
G1 Z20
G1 Z0

Measuring the distance to the bed should give us something hopefully close to 100 mm. If it is longer or shorter, we have a problem with the bed position to the endstop, even if the bed itself is level to the machine. A releveling is advised unless there is a reason to home to a position widely outside of the printing height or if leveling proves to be impossible.
Why is the error experienced?!
The culprit seems to be that the Z-offset parameter in slic3r is not updated properly when altering it. I just tested this with a ludicrous offset and it took several saving and slicing attempts to register that Z0 was supposed to be 200 mm over the endstop via the offset setting. Compare these two blocks:
G90 ; use absolute coordinates
M82 ; use absolute distances for extrusion
G92 E0
G1 Z0.350 F7800.000

And this one:
G90 ; use absolute coordinates
M82 ; use absolute distances for extrusion
G92 E0
G1 Z-199.650 F7800.000

The offset only appears factored in starting with the actual print's G1 commands. But how did I eventually manage to make it update?
Forcing the update
To force an update of all the settings, I did create a secondary printer profile (just saved the same one and in the new one set the offset back to 0) and then swapped between the two back and forth twice and then the correct offset one. This seems to be a very reliable way to force an update of this setting, as it did register every swap after the first one.
Workarounds
manual Offsetting via Filament parameter
But there is a way around that is always taken into account: we can add a custom Filament Start Code, which contains the needed offset under Filament Settings tab > Custom G-Code:
G1 Z<offset we need to be exactly at layer 0 height>
G92 Z0.3

But this is a rather clumsy way and should only be made if nothing else helps and not in conjunction with any offset in the machine setting!
Tackle the problem by the root
The problem isn't usually the offset but a bed leveled to the wrong height. To level the bed the printer should be brought to Z0 via G28 and then leveled again. If this proves futile, setting the offset and forcing an update in slic3r is needed.


Let's look at the elements and what they do:
The Heater Cartridge (blue) is the device that converts electric to thermal energy to melt the plastic. 30 and 40 W are common.
The Thermosensor (red) is there to give feedback to the mainboard.
The Filament Path (gold) in this area is made up of the nozzle and the heatbreak, it contains the meltzone.
The Heater Block (transparent green) is the mounting for all parts. It also acts as the medium to transfer the thermal energy from the Heater Cartidge to the Thermo Sensor and the Filament Path. It also acts as a dampener for the control circuit.
Now, let's put things together and omit the wires and cold end (and internal geometry of the filament path, cause I am lazy):

Now, the construction gives us several reasons for the shape of the heater block:

Ease of construction. Taking a simple block and adding a couple of holes and one cut allows very fast production.
Maximum contact surface. To get the maximum contact surface to the heater cartrige, the heater block has to make contact along its whole length, dictating a minimum size in 2 direction. The same is true for the thermosensor.
The heater block transmits temperature pretty much radially from the heater cartridge. Because it is metal, the gradient between areas is very low, but it is measureable. These would be the thermal equivalent lines on heating up:

You may easily notice that the temperature lines appear more straight as they come closer to the filament path and thermosensor. This helps to give the filament in the heatbreak and nozzle more even heating and better printing.
The mockup I made has a deliberate flaw though: a change in temperature first affects the filament and then shows up on the sensor, making the temperature in the filament path wobble to the extreme. The Heater Block acts pretty much as a transmitter just as much as a time dilation between the heating command and the pickup.
Because this arrangement is not very good, let's swap sensor and filament path around and look at the same lines.

Now we have a much shorter feedback loop, allowing our printer to react quicker to temperature changes and the filament path also gets heated more evenly. The temperature inside the filament path does change less around the target temperature. The whole block now acts mostly as a distribution medium but also as a storage for heat energy:
Up to this point, we did not take into account a very simple fact: the hotend drains thermal energy via two areas:

The outer surface of the heater block emits heat to the air.
Filament gets molten and extruded.

Factor 1 is simple and here a bigger heater block actually is positive: The thermal 'storage' capacity is dependant on the volume, so goes with $xyz \approx a^3$. The surface to emit heat from goes with $2\times(xy+xz+yz)\approx 6\times a^2$. Plotting a graph of that shows us the square-cube law: the capacity increase for one unit does increase the surface just by a fraction of that, so the storage gets better the larger the heater block is.
Factor 2 is why we need to have a storage of thermal energy in the first place: the flow of filament is not exactly the same all the time. Of course, we have moments of even flow, but we also have moments of low or no flow when the printer moves between parts of the print. This alteration of the drain of thermal energy from the heater block means that if we would go down to a bare minimum size, we'd heat up the block fast whenever we are on a move action and cool as the extrusion starts till equilibrium is achieved again. The more thermal capacity is there to store energy, the less the lack of extrusion will immediately affect the print and the more even the temperature will be in the filament path.
Fast printing?!
How is faster printing achieved with a special hotend? Well, 4 factors are used in hotends meant for very fast or very hot printing:

Longer, more powerful heater cartridge.
Longer filament path.
Extra large Heater Block to even out the temperature changes under extrusion more.
Insulating the Heater Block to the air.

One of the prime examples would be an e3D-Volcano.


What to do if filament spool won't fit in 3D printer

A spool does not need to be inside a printer. Or on. Or even next to.
My Ender 3 pulls his filament in from the rack above it, my TronXY X1 pulls it from about 80 cm to the left of it, where it hangs from a shelf.
When making a solution that pulls in filament from afar, it is necessary to make sure the path is unobstructed and works for the whole movement range of the printer without getting bent sharply, as that can snap or kink the filament.
In the case of the small printer you have, leave open or remove the door to the filament chamber and make sure to place the spool holder so it drags in the filament straight. There are even spool holders designed specifically for this printer.
There are many designs of spool holders out there, many of them free and with minimal assembly.
RE-spooling
Some printers, especially ones that only take marked rolls, might need their spool cores re-filled. In that case, you need to take utmost care: re-filling a spool needs to be without any twist to the filament or you risk entangling, and you need to make sure to not kink or bend the filament in doing so, or risk breaking at those spots.
Due to the risks involved, this should be avoided whenever possible!


With marlin firmware:

source here: filiament sensor config

//#define FILAMENT_RUNOUT_SENSOR
#if ENABLED(FILAMENT_RUNOUT_SENSOR)
  #define FIL_RUNOUT_INVERTING false // set to true to invert the logic of the sensor.
  #define ENDSTOPPULLUP_FIL_RUNOUT // Uncomment to use internal pullup for filament runout pins if the sensor is defined.
  #define FILAMENT_RUNOUT_SCRIPT "M600"
#endif

  With this feature, a mechanical or opto endstop switch is used to
  check for the presence of filament in the feeder (usually the switch
  is closed when filament is present). If the filament runs out, Marlin
  will run the specified GCode script (by default “M600”). RAMPS-based
  boards use SERVO3_PIN. For other boards you may need to define
  FIL_RUNOUT_PIN.

and this is a nice piece of hardware: run out sensor


Should I use different nozzles for different materials?

There is absolutely no reason to use different nozzles, not even if filaments do require different temperatures.

The only exception is when printing abrasive filaments (such as glow-in-the-dark and carbon-fiber) in which case you should use an abrasion-resistant, stainless steel nozzle. This nozzle can also be used to to print "regular" filaments but a regular brass nozzle has slightly more favorable properties if you do not require abrasion resistance.


Z-Axis doesn't work only during printing

I would check the gcode you're generating to make sure it's not full of "bad" z-commands.
Further, I'd take any gcode file you have and manually edit it, leaving in all the initializations, heatings, zeroing, etc.,  and then delete everything except some z-motion commands.  Run that as a test case to see what happens.
I  think it's extremely unlikely that the gantry has enough mass to force the z-screws to counter-rotate (lowering the gantry), and you'd see that with power off in any case.
edit
As Greenonline discovered, a bad choice of lead screw might cause the behavior you're seeing.  It would be a bit scary if a stock kit such as the one you bought provided high-pitch Z-screws.  Better check that out!


Pretty ugly surface remains after using support ramp. Are my slicer settings correct?

I'm not terribly familiar with slic3r, but it looks like you have a setting (possibly a default one) to slow down on printing overhangs. This was a popular "feature" in slicing software (Cura has it I know) but it's exactly the opposite of what you should be doing. When slowing down to print an overhang, the pressure in the nozzle forces the material to keep coming out at the same rate it was coming out until it subsides, and you end up with a big hanging glob of ooze like in your photo.

If your printer firmware has linear-advance/pressure-advance functionality, this can mostly be eliminated. But if not (most stock firmware), you need to maintain full speed on overhangs, and might even need to turn up your acceleration limits so that you don't get a significant slowdown just by decelerating to go around the corner.


Is there an easy way to add rounded edges to semicircle in OpenSCAD?

I'm far from a wizard with OpenSCAD, but enjoy using the program, learning something new every time. In your case, it's likely that you can use the roundanything library to accomplish your objective.
The library will present various implementations in the samples, making it an exercise for the reader to determine which module calls will present the solution.
The image below shows a part which has had the radii applied in a manner similar to your image:


How can I add auto bed leveling before print?

Rather than modifying the firmware to handle this, have you considered a pre-processing script on your computer, greping for a G29 in the G-code, then adding a G28/G29 pair at the start of the file if no G29 is found?


To use it locally you need to be able to view the desktop.
sudo raspi-config  to pull up the config menu and enable boot to desktop.
If there is no browser installed already you'll need to install one.
sudo apt-get update
sudo apt-get install epiphany-browser

Open the browser and navigate to http://localhost/

I recommend configuring access control when it prompts you. After you configure it, click login in the top right and login to use octopi.

ALTERNATIVE

octocmd is a command line interface for octoprint. If you would rather not boot into the desktop then this is the way to go.


Is a BLTouch probe used during a print after the first layer?

Your assessment is correct, after probing before printing it deploys several times, after that it is stowed till the end of the print unless you call for deployment.

The probe is used by G-code command G29; this command is used by a few printer firmwares to perform a bed probing sequence where, depending on the options set in the firmware, the surface of the bed is scanned by deploying the sensor at various locations. From these measurements, the firmware will determine the shape or tilt of the bed to compensate for deviations in Z height during the first couple of layers or millimeters of the print. Basically, it will keep your nozzle (approximately, as it is based on calculations) at the same distance all over the bed area.

Once the print starts after the G29 command, the sensor is stowed until the next print calls the G29 command (or M280 with arguments to deploy on Marlin/Duet/Smoothieware, or M340 on Repetier firmware).


How to get rid of deforming small prints?

Pla is flexible and can be shaped at temperatures as low as 50 deg C. To prevent deforming your prints in removing them, you should wait for the bed to reach room temperature. This takes about 5 minutes after a print ended.


Ender 3 V2 USB connection powers screen, but isn't detected by PC or Pi

After trying about 10 USB cables I finally found one that would work with the Ender and Pi. Specifically, it was my Logitech MX Ergo USB cable.


Ultimaker Cura problems with build platform size and overhang support

Ultimaker Cura print bed size sizes (shrinks) when you enable skirt, brim or raft build adhesion options. Try to print without build plate adhesion option if you want to push printing to the limits of the build plate. Furthermore, you mention the use of PVA, using 2 cores, the priming print tower also needs space to be printed, this can be also limiting your build plate space. Note that you can define where to print the tower, you could try locating it in a corner where the fan does not reach.

From your screenshot with the fan flat it appears that you have selected dual extrusion. Note that the bed size depends on the amount of cores you use, from Ultimaker:

  Left or right nozzle: 215 x 215 x 300 mm (8.5 x 8.5 x 11.8 inches)

  Dual extrusion: 197 x 215 x 300 mm (7.8 x 8.5 x 11.8 inches)

As an example I have made a 7.44" cylinder of 2" height and put it onto the UM3E build plate to show the differences when you use dual extrusion.

This image shows the cylinder when printed with a single core:

This image shows the same cylinder, but now with enabled "Extruder 2" as the "Support Extruder" option:

Having an Ultimaker 3E myself, printing PVA might not be very good choice as you need to print a lot of support material when printing upright. PVA cooks easily even in the B core, it also needs to be very dry, PVA takes up moisture very fast and becomes useless after that. At work we have much better experience with break-away support material.

Another consideration why you should not print this upright is the orientation of the layers. It is generally known that the layer to layer bonding is less strong that the material itself, it at least provides a lot of notches from which cracks can initiate and grow. This means that if you want to print this, you should lay it flat, this way the centrifugal force is in line with the layer deposition direction.

With the correct layer height (read thin layers), you should be able to print this flat without support. I have printed similar structures like turbo turbine wheels with similar overhangs without support.


In OctoPrint when receiving temperature data (M105) what is T0?

T is the selected tool, T0 is the first hotend tool. If you only have one hotend, T and T0 are exactly the same.

Do note that G-codes are described on the G-code wiki page, for M105 you can find:

  The parameters mean the following:
   - T, T0, ..., Tn - extruder temperature. In a single extruder setup, only T will be reported. Some firmware variants will report no T0 in multi extruder setups - in that case T is to be considered the temperature of the first tool. Otherwise, T should be considered the temperature of the currently selected tool (which will be repeated in one of the Tn entries)
   - B - bed temperature
   - C - chamber temperature
   - @ - Hotend power (Prusa only)
   - B@ - Bed power (Prusa only)
   - P - PINDAv2 actual (Prusa MK2.5/s MK3/s only)
   - A - Ambient actual (Prusa MK3/s only)


File too big to open in Tinkercad. How can I shrink it?

If you have 3D software like Blender you can import your model and use the decimate modifier to lower the number of vertices and then re-export.
Here is a link to how you can do this: Simplify Geometry with the Decimate Modifier in Blender 2.9.