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Installing multiple versions of ChiTu side by side
I am using two resin printers based on the ChiTu software (Creality LD-002R and SainSmart Kumitsu KL9), and the former uses ChiTu 1.6.2, while the latter came with 1.6.1. I believe both will work just fine with the latest version, but it occurs to me that having separate copies of the software may be a good idea to keep configurations separate as well: Creality's version of the software came pre-configured (and the settings are undocumented!), while the SainSmart manual documents the software settings.
I don't want to go back-and forth between two sets of settings manually — the secret recipe approach has poor UX and time's a wastin'. I am wondering if there is any concern with installing multiple copies of ChiTu. And if anyone has a smarter way to accomplish the same (printer profiles? INI files?), I am all ears.

Running multiple versions of the same software did not sit well with the software person in me, so I dug a little deeper.
ChiTu has a "settings" button to the right side, and under that section it is possible to configure different, separate printer profiles. That may take care of the differences if properly configured, unfortunately only some printer profiles are pre-loaded. ChiTu 1.6.4 includes the Creality LD-002R profile, while the very recent Kumitsu KL9 is not predefined (yet), but the manual comes with a screenshot of the parameters just as they need to be entered.


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How to force Cura to walk through a layer in one run?
I already tried a lot settings in Cura and try to search for a solution but without success. Maybe someone got this issue and solved it.
I want to prevent Cura from printing such gaps at the wings to make it in one run. With ironing one run would (hopefully) bring better results. See the animation for what I mean.

Why want to do this? I hope to prevent thes ironing issues shown in the following pic.

There's no way to do this in Cura. Could you perhaps describe (and show a photo of) the print quality problem you're trying to solve?

Are you asking it to print straight across the gap, retracting the filament there instead of making the extra pass on the other side?

@DoxyLover yeaht that´s what I want.

The photo is really unclear (extreme low resolution, out of focus, blurred) and you still haven't explained what you want and what the problem is. Is this layer the ironing layer and something about returning looks cosmetically bad?

I am not aware of a general solution.
For your specific issue, try rotating the object 90 degrees around the z-axis.

This answer hints to changing the print orientation to prevent the slicer to create "pockets" that are filled later. But, since we cannot see the rest of the design, or for more complex designs, it is possible that you cannot change the orientation. Maybe concentric pattern will help you, but that doesn't always works or looks fine.
However, there is a way to solve this (but it requires a different slicer then Cura) using the upcoming release of PrusaSlicer as discussed during Prusa Live #3, live stream @ June, 17 2020 under "Ironing & Monotone infill". The monotone infill will fill in the "pockets" in the same direction to prevent defects caused by build-up of filament at the wrong side. This feature may be very useful for better filling in layers.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

sort: votes


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Can photopolymer resin colors be mixed?
Can different resin colors be mixed to generate new colors? I use eSun water washable resins, but I am happy to switch if this is a different vendor's capability.

water soluble or water washable?

washable. Fixed.

Yes and No at the same time
First of all, yes, you can mix resins. However, you should only mix resins that are of the same makeup, as in one brand and type. Why? because different types of resin have different compositions and different polymerization types. Mixing different types can result in unpredictable behavior, and not working at all!
To test, use a tiny amount of your brand and type matched resins and apply to the vat, then print something really tiny, like just 2 or 3 layers of a 20x20x20 mm cube.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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Bowden-direct hybrid
I've got a direct drive extruder printer, that I have equipped with a Bowden-tube to give it a nice and defined filament path from my spool and to protect it from moisture when it exits my drybox. I've noticed that this 1 m Bowden tube adds quite a bit of friction to the system. I am keenly aware of it as feeding filament form the drybox into the tube by hand is quite a chore already, especially with high friction materials like PETG. Also I notice that I can sustain only lower volumetric flow without skipping or underextrusion after adding the tube.
So I figured, why not have a motor on both sides of the bowden tube? A big and heavy one at the entrance, providing a baseline pressure on the filament. And a comparatively light one on the other end, adding that fine control you want for your retraction, rather than trying to implement that via a 1 m wet noodle full of static friction.
Seems like it would give you the best of both worlds. Not quite as light as a full Bowden system, but you could have all the control of a direct drive system, with much less of the weight/flow rate tradeoff.
Anyone aware of this being done before? Or any good arguments as to why it is a stupid idea? Seems like a fairly straightforward mod; in the simplest implementation, just add an additional extruder of the same spec on the other side of your Bowden tube, and split the control signal to be the same amongst both motors.

A Bowden tube is by design fairly small diameter to match the filament within, constraining the forces applied by the remote extruder mechanism. As you've noted, friction is a consideration.
For your application, you would not have to have such a tightly constrained diameter. You could use a Bowden tube for 2.85 mm filament, if your direct drive extruder is made for 1.75 mm filament.
You'd have the environmental control of the smaller tube, the path control and all of the other benefits, but none (or little) of the friction.
Additionally, you would not have the complexity of managing retraction or synchronizing feed that a dual motor system presents.

Thats what I thought; but my polybox dry box came with some 2.85 sized tubing, and the friction in running 1.75 mm filament though was absolutely horrible. Maybe just a bad batch, or something stuck inside? Didn't have any kinks or obviously deformed openings. Regardless of the impact of the tube though, a small extruder on the hontend to provide fine control combined with one at the inlet for baseload pressure might make sense.

Sounds like bad tubing, probably not PTFE.

I have a similar setup with one of my printers (that is using 1.75 mm filament), this answer is therefore my own experience with guiding tubes from spool to extruder (my previous was a direct drive extruder, the latter uses a Bowden setup, but both with a tube leading up to the extruder).
Initially I used smaller diameter tubing (inner diameter of 2 and 3 mm, that is commonly used for Bowden setups for respectively for 1.75 mm and 2.85 mm filament), but when I changed to 4 mm inner diameter (and 6 mm outer diameter) all friction was gone. The benefit of using 4 mm inner diameter is that it fits over the 2/4 mm ID/OD tubes, and as such I slide the larger inner diameter tube over a piece of 4 mm outer diameter, forme, this also simplifies feeding the filament to the extruder.

Yeah that is the tube that came with my polybox; 4/6 mm. Perhaps I only tried with PETG but the friction there was insane.

@EelcoHoogendoorn I seldomly print in PLA, so my experiences are with PETG as well. I guess your tubes might not be so low friction, are you sure they are PTFE? PTFE tubes are soft, pliable, the harder tubes are often not PTFE. See also this comment.


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Is there a convenient GUI tool for configuring Marlin settings?
I am looking for a tool to configure various runtime settings of Marlin firmware (e.g. bed leveling) that would be accessible from a computer rather than from the LCD menu on the printer.
In a slightly similar vein I found this marlin-config tool from github user akaJes. However, this tool configures build-time settings of the firmware (e.g. which menus to include in the first place into the build) whereas I'm looking for something that controls the settings and printer when the firmware has already been uploaded.
The main goal in my search is discoverability - I know I can find the appropriate G-codes for whatever I want to change, but I don't necessarily always know in advance that a given setting exists in the first place.


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Best filament for epoxy bonded structural parts
I am planning to print some large structural components, and I intend to form them by glueing together a number of printed parts, and skinning those with composites. In other words this plastic needs to bond well to epoxy.
What is the optimal material here? My logic makes me arrive at fiber-reinforced PC as the only good choice. But please point out to me if my logic goes wrong somewhere.
PETG/PP/PA/ABS/ASA are all out of the window. I want this to bond well using run off the mill laminating epoxy. And by 'bond well' I dont mean 'cant pull it off with the first try with my fingers', but I mean I want the glue bond to be about as strong as the underlying material, and that just isnt going to happen with any of the above. I know that for every plastic there is some $100 a tube toxic goop you can get to stick with a few dozen steps of surface prep; but im not going to use that as a laminating resin.
Moreover, I want a fiber reinforced material. Not for the strength per se, but for minimum warp. When printing multiple 30x30cm pieces, I want them to slide together without gaps (or the gaps I designed into it); and if the piece as designed was intended to be straight after assembly, i want to to be straight after assembly. Its frustratingly hard to find quantitative information on warping properties. But polycarbonate without fiber reinforcement does not fit the bill, thats for sure.
Plain PLA might be another decent option. I cant find much quantitative information about bonding it to epoxy, but at least its not a known no-go. There is some worry about the heat of curing the composites deforming the PLA though.
PVB might be another good bet. Easy to print with, and great at bonding. Might be sensitive to solvents in your laminating resin though.
Of course all other criteria for a nice filament apply as well; consistent extrusion, layer adhesion, all that.
Is CF-PC the way to go? I see very little in the way of reviews about CF-PC; it does not seem to be that popular a combination, which is a bad sign, but I cannot discern much reason for it.

Just an idea, but if the surface was formed of trapeziodal slots (or some other undercut profile) then the epoxy would be physically connected to it instead of only chemically. I guess you would need rather runny epoxy.

Yeah; I've only recently gotten into fiber reinforced filaments and I noticed their surface microstructure trends to be quite rough. Indeed you might take that even further by modifying the surface on the gcode level. It might suffice; but it sounds like a lot of testing before you know how it plays out in practice; and I'd rather spend money on a solution that should 'just work'. But it's an interesting avenue for sure.

[* sp: trapezoidal, of course.]


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How do I know if a filament is abrasive?
There are tons of fancy filaments around. And a lot are super nice to look at or have super cool properties, like carbon-filled nylon being comparatively far stronger than other material, wood fill is aesthetically pleasing and even just Glow in the dark! But a maker space nearby just banned any of those as abrasive filament. But, how can I know if my filament is abrasive?

Usually, the filament is advertised as being abrasive. Or, the advertisement/filament properties say to use a (hardened) steel nozzle.

glow in the dark is extremely abrasive, wood notsomuch.

A filament made of pure plastic won't be abrasive. The abrasion comes from the added particles.
Filaments with added particles of any kind (there are not so many after all: glass/carbon fibres, metals, glow in the dark, wood, stone) will usually be always be advertised as such because they always carry a higher price tag compared to the plain plastic, therefore you know that it contains potentially abrasive particles.
Once you know that particles are added, most of the time they will be abrasive: as far as I know, only cork is not, any other kind of particles I listed (including wood particles) may easily scratch brass.
If it were your printer, we could discuss how much each kind of particles will abrade, but in your case the ban seems to be complete, therefore only plain plastics (including "plus/+/Pro" blends, like for PLA and ABS) are allowed.

I was going to write a similar heuristic answer like this before you did it first, but I was unsure if it's complete. I seem to recall at least some nylon variants being warned about as abrasive and don't understand the mechanism there.

@R..GitHubSTOPHELPINGICE nylon 6, 66, 12 are not abrasive by themselves. Those variants you mention maybe comprise fillers?

Glow in the Dark isn't always advertized as containing particles

Do note that diamond particles filled filament exists that is not abrasive! (According to their claim and reported tests)


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Heated bed is not heating up
Hello I am building a clone of Prusa MK2. So I connected all the connections to the RAMPS 1.4 shield. I used Pronterface successfully to set the temperature of bed, but it did not heat up... So I tested the RAMPS D8 D9 connectors which showed 2 volts and D10 measures 12 volts. I replaced the MOSFETs and now it shows 4 volts. I also tested my heated bed. The + and - terminals measure 2.2-2.3 Ohms, and the multimeter beeps when I test for continuity and measures 0.5 Ohm.
Can someone help me what the issues are?

How can you measure a resistance without continuity? A heated bed will have a resistance in the order of 1 to 2-ish Ohms, so that should be okay.

I have shown you the image. When i test for continuity it measures 0.5 ohm and now it beeps


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Prusa i3 MK3S supports fail to print on bed
My printer currently has issues printing supports of multiple objects. The support gets smushed around the printbed after a while. I’ve attached a picture of the failed support.
I’ve tried lowering and raising the first layer height but it doesn’t seem to have effect. Also I’ve tried raising the heated bed to 70 degree.
How could it happen that it’s pushing the supports around?
I’m using a 0.25 mm nozzle, bed heated at 70 or 60 °C, nozzle at 210 or 215 °C, layer height lowered 0.050 and raised 0.050. I use 7x7 mesh bed leveling. Reran calibration wizard.

Serious underextrusion here but only in the parts on the sides.

It’s printing the supports like that. I’ve now readjusted the first layer up 0.1mm, wich i think was way too much but it seems to have better results than 0.05 up from where I was printing fine before.

What's your first layer? a 0.25 mm nozzle only allows to print up to 0.2 mm thick layers! Also, wipe down your print bed with some alcohol to ged rid of fingerprints.

It is difficult to see, but over-extrusion and a nozzle too far from the bed is my best guess based on this image quality.

@Marco: There are all sorts of ways you can perturb and possibly "improve" the first layer by adusting the distance to the bed and otherp parameters, but the only one that's not going to break other things is getting the distance right (accurate).

@0scar it's a very very small piece, this image is more detailed than my eyes can see. Why do you think over and the other thinks under?

@marco: whether it's over or under depends on how much you've messed up the distance to the bed.


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Ender 3 Layer Shifting
I recently got an ender 3.
It was working well for 2 prints. I managed to print two small items which were upgrades for the printer (filament guide and cable clip).
Following this, I tried to print some larger designs and I noticed it began shifting the layers on the x-axis...
How do I fix it?

Have you made sure that the belt for the x-axis is quite tight?

Can you confirm that you're sure this is X (left/right, the axis the hotend carriage moves along) and not Y (the axis the bed moves along). Y-axis layer shifts are a lot more common.

If the layer shifts really are along the X-axis, it's likely that the gantry is not square with the Z-axis (leaning), thereby making the nozzle collide with the print. In addition to squareness, check that all the Z rollers are tight on the Z-axis aluminum extrusions and that there is not any play in the one on the right especially. The places where the gantry bolts onto the plates that hold the Z rollers have a plenty play to mount them non-square, and having this wrong is a common problem. Also, of course, make sure the bed is level (with respect to the nozzle; see general bed leveling info)

Yes, it is the axis. I will try that too, I saw an upgrade for a z-axis spacer too.


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New filament makes brittle prints
I recently bought 5 spools of white 1.75 mm PLA off Amazon.  However, I experienced some very strange behavior when I started to print with it.  First, the filament wouldn't stick to the print bed.  I'd had no such trouble with the past several batches of filament (all from different makers, I think - my usual supplier is closed for COVID), but this filament refused to stick - or rather, it failed partway through three consecutive prints.  I squished the first layer into the bed, but it didn't help.  Not sure what else to do, I applied glue stick to my print bed (despite having a special print surface that has worked quite well on its own for over a year).  Well, it worked - too well.  The next print adhered firmly to the print bed, and applying pliers and a vise succeeded only in explosively shattering the parts, leaving most of the bottom few mm still stuck fast to the print surface.  I finally managed to remove the remains by letting it cool, then heating the bed quickly to ~75 °C and applying steady moderate torque with pliers for 5-15 seconds.
That was not a desirable outcome, so I cleaned the print surface with water and then alcohol.  Unfortunately, the next print I did had the same problem, and snapped during attempted removal.
This leads into the second, somewhat more fundamental problem with this filament - I don't have numbers, but it seems way more brittle, and a little weaker, than the average filament.  The parts I printed were ones I've printed before, and they generally hold up to more abuse than the ones I've printed with this new filament.  If I had to put a number on it - the new filament has maybe 50 %-75 % of the strength of most filament I've used, and/or is 150 % as brittle?  Yeah - I just tried to shave off an edge with a deburring tool, and rather than form nice little plastic curls, it crackled and shot tiny chips of plastic.  (Except for one corner, which was well behaved some of the time?)
Can anyone diagnose my filament from these symptoms?  Is there something I can do to fix it (e.g. bake it for 8 hours or whatever), or should I just return it?

At least the removal problem is your technique. You should never be putting force on the print to remove it. Use the "putty knife" tool or similar to separate it slowly from bed starting from edges.

@R..GitHubSTOPHELPINGICE A metal tool would likely damage my print surface, and a plastic tool almost certainly wouldn't make it under the print to start with - wouldn't have an edge both strong and thin enough to fit.  Do you have any suggestions?  Note that I've removed hundreds of prints from the bed before, and this is the first time any prints have been so stuck.

What type of build surface do you have? A putty knife type tool should be fine on buildtak clones and glass at least, and I would expect on other types too. You run the blade along the surface similar to how you use a razor blade to clean adhesives off glass or burnt-on mess off a flat-top electric stove, not downward in a way that would dig in.

As for your problem with brittleness and adhesion before using the glue, I wonder if the filament just has poor size accuracy. If the diameter is slightly too low, you'll have underextruson that would explain all these issues. Do you have a high-precision caliper (better than 0.1 mm) you can use to measure and see?

@R..GitHubSTOPHELPINGICE I have one from geckotek.co - it's a ~2.5 mm layer of some kind of plastic (reminds me of nylon, maybe?).  A metal knife would risk scratching or gouging the surface.  (The build surface instructions recommend against metal tools.)  Yeah, I have calipers that measure to two decimal points - I got 1.76 mm at several points on the filament when I just checked, and 1.75 mm in at least one spot.

Sounds like the print temp might be off. different materials like different temps, so play around with that setting, say +20 and -20 from what you have now, and see what's worse and better, then hone in.


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"configuration files" issue when trying to run Ultimaker Cura on RPI 4
I have installed Cura on my RPI 4 by using the "sudo apt-get install cura" terminal command.
Whenever I try to run the application, however, I get this:

Is there something wrong with the configuration files? I have tried clicking the "Backup and reset configuration", and even deleting the configuration files folder. But it doesn't help.

The regular version of Cura has system requirements that the Raspberry Pi cannot meet, including the GPU required to run it.
However, it looks like you can try an experimental version of Cura here.


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Artillery Sidewinder X1 3DTouch not working
The printer I am working on is an Artillery Sidewinder X1.
I have fitted it with a 3DTouch (BLTouch clone) bed leveling probe purchased from Bangood.
I have printed a mount for it and plugged it into the main board. Once that was done, I edited the firmware and enabled all settings for the 3DTouch roughly following the directions from Teaching Tech's video here.
After flashing the firmware, an error message appears on every boot saying:
Failed to enable Bed Leveling
echo: Bed Leveling off echo:
Fade Height Off ok

After pressing confirm, ABL routine does not work. It homes the X-axis, then the Y-axis, deploys and stows the 3DTouch probe once. It also will show an error message for a split second (so I am unable to know what it says) the comes up with an EEPROM message.
Auto homing does the same thing as ABL routine but with a different error:
STOP called because of BLTouch
error - restart with M999
Error:Printer stopped due to errors.
Fix the error and use
M999 to restart. (Temperature
is reset. Set it after res[e]t

I have also zipped up my Marlin firmware configuration I am currently using. They can be found here: here.
My servo pin is connected to D11 and my two wire pin is connected to the ZMAX endstop. Here is a diagram:

My personal experiences with 3DTouch is that they are of inferior quality opposed to the original, at first they work (most of the times), but they will break fast (from experience, I've had about 4 of them on different printers, all died eventually).

@0scar I made this post almost half a year ago now when I first bought the sensor. It has been working fine ever since and I have never had a problem with it.

Ok so I did a bit of testing with the wiring and it turns out I just had the 3DTouch in the Z- socket instead of Z+ :-) .
Another idiot mistake from me!


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Removing test print from magnetic flexible paper coated build plate
I have a Monoprice MP10 with magnetic flexible paper coated build plate and I have just tried printing bed level test which is, of necessity, very thin on the build plate.
Watching the item print, I saw that the bed level was obviously way way off at the back left corner and down the left side. I was printing with PLA. There was no point in letting the print continue so I stopped it, let the build plate cool down and tried to remove the print.
The bottom line and right hand side came off cleanly but the top left corner and all down the left side stuck firmly. As it was so thin a layer there is no chance of getting something underneath an edge without damaging the paper surface. I tried acetone but this had no effect other than turning the surface white and thin cracks appearing in the paper surface. Wiped down with alcohol which toned down the white but was no help in getting the thin layer of PLA off.
I tried reheating surface, no joy. Does anyone have a foolproof way of getting this off as soap and water don't work either?

you have a scraper?

In my experience with the Creality magnetic textured build surface, it's easier to remove a thin print while the surface is still pretty warm -- probably between 35 °C and 40 °C -- as opposed to fully cooled to room temperature.
If the print is very thin, however (as when the nozzle is much too close to the build surface) printing over it may be the only sensible option.  In fact, if the print residue is too thin to get a scraper under, it likely won't show in another print with the same color/type filament, so you can just ignore it unless you're changing color or material.
BTW, don't use acetone.  For anything, unless nothing else will do the job.  Too flammable, too toxic, and it dissolves stuff you don't want to dissolve (but won't do anything notable to PLA, which is why you can't do acetone vapor smoothing with PLA).

You could try freezing your bed with cooling spray around the print and then wait some seconds and try peel it off.
I had the problem once on my PEI sheet and it did help. I used this spray: Spray
But make sure you don't break any electric parts on your printer.

Could putting the bed in the freezer accomplish the same thing? Not being sarcastic, just a thought.

You could print something on top of it, like a giant square covering the whole affected area. You should use some slightly higher temperatures than usual to make it adhere good (e.g. 75 °C bed 210 °C hotend), make sure that you print several layers.
There are 2 options removing the new print when there is an elevated temperature in the bed left after printing, or removing after a complete cool down.


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Passing from nozzle diameter 0.4 mm to 0.2 mm causing filament jamming in heater
Im using Prusa Slicer 2.1 for my FlyingBear Ghost 4.
I just changed my 0.4 mm nozzle for a 0.2 mm but it seems to jam in the heater probably due to too much filament trying to get out by the nozzle. Where is the setting to reduce the filement speed and how much I should reduce it?
Here are my settings:
Config.txt

permission fixed

0.2 mm and 0.4 mm are half the diameter, but the maximum flow is not just half: Flow scales with the area. The 0.4 mm nozzle has an area 4 times as the 0.2 mm one:
$\frac{A_1} {A_2}=\frac {0.2^2}{0.1^2}=4$
You need to reduce print speed or the volumetric flow by this factor or make sure your printer can handle the increased flow by reducing the viscosity of the melt - for example by increasing the print temperature.
Also note, that a 0.2 mm nozzle can't be operated with layer heights above 0.15 mm.

Ok, where do I change the settings in prusaslicer?

@EricBrochu reduce print speed, I think it's usually 60 mm/s, so it would be 30 mm/s

@Trish: That should be 15 (1/4). But it might be possible to get by with more if the limiting factor at 60 was melt rate rather than viscosity.

@R..GitHubSTOPHELPINGICE yes, brainfail XD

Here's where you change the speed in Prusa:

As Trish said, you're likely trying to push too much material through too fast.
Steps you can take:

Increase print temp
Decrease print speed
Slice for thinner layers
Don't forget to adjust your nozzle diameter and/or extrusion width(s) as well.

I'd personally start with increasing my print temp 10 degrees and cutting my print speed in half, as well as making sure I had 0.2 mm nozzle and extrusion widths.

you don't answer the question at all.

I addressed the issue described in your title. Now I've also answered the question in your question. :)

What about the speed of the filament entering the heater. I do not think that Print speed is a problem, its the speed the feeder pushes the filament.

Filament advance speed is calculated, and essentially equal to the demand (how much output you need per second) (minus offgassing), which is based on your travel velocity (feed rate), layer thickness, and extrusion width. For more details, please see steps 2, 3, and 4 in the part of my answer of which you were originally critical.

i always print with 0.1mm layers, can't go thinner.

The discussion about slowing the print speed is important, but in my experience it is not at the root of the problem, and slowing down printing may make it worse.
If ny "heater" you mean the complete hot-end, then I suspect you are jamming in the cooler part of the hot-end.  This cooler part is separated from the heater itself by the heat break, which is often a thin-walled metal tube.
The hot side of the heat break is heated by the heater.  The cooler-end, the cool side of the heat break, is cooled by two things:

cold filament being moved through it and
airflow from the fan over the heat sink fins.

It is heated by:

Thermal conduction through the thin metal tube
Convection airflow from the hot-end vertically and over the cooler-end
Hot filament being pulled through the heat break during retraction.

When you are printing with a smaller cross-section of extruded filament, the slicer program should adjust the flow rate and speeds based on the lesser volume of plastic extruded for a given pressure.  Unfortunately, this is less plastic, so the filament cools the cooler end of the heat break less than it would if the feed rate were higher.  As a result, the temperature of the cooler end goes up.  If there is insufficient airflow to keep the cooler side below the softening point of filament, the filament softens and jams inside the cooler end.
Of course, if your jam actually is in the hot end, this discussion is not relevant.
But, I have found with my Prusa i3m3 that I have had problems with jamming in the cooler end, especially when I printed filament with a higher melting temperature, ABS in this case.  I reduced the area of the airflow so that no air could pass through other than by passing over the heat sink fins, and the ABS printed correctly.
All of 3D printing is a balance of one factor against another.  It is hard to lose, though, by increasing the cooler-end temperature.  All will seem well until you print something with a lower flow, or a higher retraction rate, or you try using a higher temperature for the same filament.  Then the jam can unexpectedly occur, or, perhaps worse, it can be an intermittent jam, or there can be a lot to sticktion, and printing becomes prone to gaps, or occasional under extrusion.

Ah, now it makes sense - yes, smaller nozzles do create heat creep, in addition to being challenged with high flow due to viscosity.


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Bed probing feed rates
I was watching a friend's Prusa run the bed-probe routine and I realized how pathetically slow mine is and takes forever. I want to speed it up.
What parameters in Marlin's Configuration.h do I modify? Also, it seems to retract for the second "accurate" probe by like 10 mm which could be reduced by 8 mm or so. Where is that one? I looked through but can't be sure. Also, could I just change the feedrate in the pre-script?
#define DEFAULT_MAX_FEEDRATE { 300, 300, 8, 50 }    // was { 400, 400, 8, 50 }

To speed up the probing for a touch sensor, a "High Speed" option is available in Configuration_adv.h which is by default disabled (//#define BLTOUCH_HS_MODE) as not all printers/sensors are able to use this.
You can also increase the homing speeds in your Configuration.h file.
// Homing speeds (mm/min)
#define HOMING_FEEDRATE_XY (50*60)
#define HOMING_FEEDRATE_Z  (4*60)

.
..
...
..
.
// Feedrate (mm/min) for the first approach when double-probing (MULTIPLE_PROBING == 2)
#define Z_PROBE_SPEED_FAST HOMING_FEEDRATE_Z

// Feedrate (mm/min) for the "accurate" probe of each point
#define Z_PROBE_SPEED_SLOW (Z_PROBE_SPEED_FAST / 2)

However, you can simply speed up the movement between probe locations by setting the movement speed directly through G-code. The G29 code, used for automatic probing of the bed surface is described in "G29 Auto Bed Leveling (Marlin - MK4duo)". The S parameter in G29 can be used to set the movement speed between probes, where the units are specified in "units/min", e.g. mm/min.
Note that you potentially can change the Z-height for deployment:
/**
 * Z probes require clearance when deploying, stowing, and moving between
 * probe points to avoid hitting the bed and other hardware.
 * Servo-mounted probes require extra space for the arm to rotate.
 * Inductive probes need space to keep from triggering early.
 *
 * Use these settings to specify the distance (mm) to raise the probe (or
 * lower the bed). The values set here apply over and above any (negative)
 * probe Z Offset set with NOZZLE_TO_PROBE_OFFSET, M851, or the LCD.
 * Only integer values >= 1 are valid here.
 *
 * Example: `M851 Z-5` with a CLEARANCE of 4  =>  9mm from bed to nozzle.
 *     But: `M851 Z+1` with a CLEARANCE of 2  =>  2mm from bed to nozzle.
 */
#define Z_CLEARANCE_DEPLOY_PROBE   10 // Z Clearance for Deploy/Stow
#define Z_CLEARANCE_BETWEEN_PROBES  5 // Z Clearance between probe points
#define Z_CLEARANCE_MULTI_PROBE     5 // Z Clearance between multiple probes
//#define Z_AFTER_PROBING           5 // Z position after probing is done


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Retraction fine but recovery occasionally just doesn't happen
I'm having issues with retraction. My printer prints very well normally, but has an intermittent problem with retraction: the retraction itself always happens, but sometimes the subsequent recovery just doesn't take place, which obviously results in gaps in the extrusion. I'm running out of diagnostics to try - can anyone suggest what might be causing this? I have:

Removed the stepper from the extruder so it's free running
Changed the driver board (to a newer design, although both are based on the TMC2130)
Reseated all the connectors
Switched off the driver's "StealthChop" function in favour of the fallback "SpreadCycle"
Tried G-code produced in Prusa Slicer and known good code from Cura (taken from a retraction test put up on Thingiverse)
Updated Marlin from 2.0.4.4 to 2.0.6.1

The machine is a Creality Ender 3, although the previous owner (who has reported no problems when he was using it; he's a friend, not an anonymous eBay seller) replaced the board with an MKS Gen L and the drivers with Big Tree Tech TMC2130s in SPI mode. The extruder stepper is the stock Creality model.
Other relevant settings:

VRef on extruder driver is 0.875 V. As far as I can make out, the maximum suggested for these motors is 1.0 V
Extruder current is firmware set to 900 mA
Maximum feed rate for E is set in firmware to 25 mm/s, which I think is fairly low
DEFAULT_MAX_ACCELERATION is set to 5000 mm/s2, but DEFAULT_RETRACT_ACCELERATION is set to 500 mm/s2 and (with no M204 instructions in the G-code) I would presume this takes precedence

I'm tearing my hair out here! Most of the changes I listed above had no effect, but I would say that the change to SpreadCycle for the driver reduced the occurrence and it seems to be more prevalent when the retraction distance is increased (4 mm is worse than 2 mm). The thing that's really confusing is the lack of symmetry - retractions always work, feeding forwards during printing always works, but feeding forwards during recovery sometimes doesn't - the stepper just doesn't turn.
I can increase the VRef or current, reduce the retraction speed and acceleration further and perhaps one of these will be the answer, but I'd like, ideally, to understand what's going wrong so I can target my fix. Does anyone have any ideas?
Edit
After comment discussion on overheating drivers, I measured a steady temperature of 77 °C with a thermistor pushed to the bottom of the stepper driver's heatsink fins. Is this expected or could it represent an overheating problem?
Edit 2
It turns out that the terminal is periodically printing a message indicating there may be a problem with the driver temperature (e.g. 2020-09-14 23:22:15,877 - Recv: 00:00: E driver overtemperature warning! (900mA)).
If there is a continuing problem, the stepper current should be throttled automatically, which is not happening. Nor is the actual overtemperature error condition being reached, because if this happened, the driver should completely shut down until it cools 25 °C and I believe Marlin should abandon the print at this point. Neither of these things seems to be happening, but perhaps the raised temperature is causing my stepper issues, nonetheless.

As I understand, DEFAULT_RETRACT_ACCELERATION is only relevant if you're using firmware retraction (G10/G11). Normally I'd assume not (it's not in stock Ender 3 firmware), but since there's clearly custom firmware you could be - are you?

No - retraction is done the old-school, slicer way. I hadn't realised this was only relevant for firmware retraction, but of course how would it know a move is retraction otherwise? DEFAULT_ACCELERATION is also set to 500, though, and I think that is relevant for all other moves that include an extruder parameter. If acceleration was set too high, could it cause long feed instructions to be completely, but intermittently ignored?

I don't think so, at least not directly. Is it possible the E stepper driver is overheating from driving high-acceleration retracts/unretracts, which are high-load operations, and shutting down momentarily while it returns to operable temperature?

Also, are the skipped recoveries entirely deterministic for a fixed gcode file? Or do they vary every time you print it?

Overheating probably is a possibility. I haven't measured the driver temperature and although there is a case fan, ventilation is perhaps less than it could be. I'd thought the low current, speed limits and apparently more efficient chopping algorithms the TMC2130 uses might make this a lower possibility, but I also don't know how an overheating driver might behave: this might be a classic indication for all I know. If I can measure the temperature of the heatsink, what range might I be looking for to indicate a problem?

I believe the skipping is happening at random. It's certainly different between the two (different versions of the) TMC2130 boards I've used.

Did you flash custom firmware?

@BobSammers: I'm not sure what temperature is the limit, but my understanding is that most drivers have overtemp safety to shutdown when temp is too high.

@Trish Yes. It's stock Marlin but with changes to the two config files to support the hardware changes that the previous owner made to the printer. I didn't make the edits but I have seen them, merging the 2.0.4.4 config files I inherited to 2.0.6.x. To my limited understanding, they look like sensible alterations.

@R... Yes, the TMC2130 datasheet talks about this. It "prewarns" at 125C, and an error condition and shutdown occurs at 150C; it then won't do anything until temp drops to 125C. As I seem to be getting only warning messages (see edit above), sporadically, and nothing more (and Marlin's automatic current reduction / print cancellation isn't kicking in), I don't know whether this is the whole story: this doesn't seem to be the right set of conditions for instructions to be dropped.

@BobSammers I have the exact same issue on my tevo tarantula pro. No custom hardware installed, and, I don't get any error messages in the terminal (trying via octoprint). And I'm nowhere near the solution...

The weird thing though...I created a gcode file, the only thing it does is retracts and immediately recovers, multiple times. And I never seen this issue with this test. But as soon as I start printing something, the issue appears

@BobSammers if you're still struggling with this issue, I have managed to solve mine: the VREF on stepper drivers was about 1.3V which is too high. Lowering it to 1.2V completely solved the issue for me. So I'd suggest trying lowering it by 0.05V and see what gives the best results!

Thanks for your comments, @Timofey. I think I've solved this and in a similar fashion to you. I've done two things: I've reduced the stepper current by 50mA and reduced DEFAULT_MAX_ACCELERATION to (from memory) 2000mm/s2. The first value was already at the default and the other I didn't think should be having any effect, but between them they seem to have sorted out the recovery and stopped the warning messages in the log. Classic change two things, don't know which has worked rookie error, but I'm happy with it as it is!

This could also be unrelated to the extruder controller.  I've had issues like this when molten plastic injected itself into a gap between the heatsink and the hotend and solidified.  The result was increased friction which could cause the extruder motor to overheat or cause the filament to slip during retraction recovery.


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Problem with grid infill (line positioning)
I have a problem with the grid infill on my BCN3D+ Dual Paste extruder: when I print a structure the lines of the infill are not evenly printed, every two lines the gap between the lines is higher (see the photo) while in the Simplify printing preview (preview image) the space between the infill lines is the same all the time. Do someone know if it can be a problem of the printer or a Simplify command?

What kind of extruder is that?

My guess is that the nozzle assembly just isn't rigid and is deflected according to the last direction it moved or something like that.

It happens with different printing materials (ceramics before calcination) and today I tried with another 3D printer (same model) and It didn't happen, so it should be something of the printer itself, it is a BCN3D+ double paste extruder

It looks like a case of one axis affecting the other.  This is a subset of cases where things are not rigid enough.  Basically the movement direction in X is causing an offset in the Y, or whatever you want to call the axes.  It is present in small amounts in all screw-driven setups where the screw essentially acts as a wedge, and can be in others for various other reasons.  The solution is to tighten up your linear bearings/slides so that there is less transverse play.
There is also a chance that you are trying to print beyond the resolution of your printer, in which case it is "rounding" to the nearest within its capabilities, but that seems less likely.

how does this correlate with the information given? The BNC3D is not screw driven on the X axis - it is belt driven.

The correlation is in the direction of one axis affecting the other axis.  There are other ways such as having a belt connection location not directly in line with the effective CG (center of force?) of what it pulls.  It's fairly easy to check for by moving and watching the nozzle and the solution is the same regardless of belt or screw - adjust the linear control elements to reduce transverse slop.


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Printer is using BLTouch to home but it is not using it to auto level
I have recently set up my Ender 3 with an SKR MINI E3 V1.2 and a BLTouch which I have been using for a while. After many troubles with compiling the firmware, I managed to compile and upload the firmware; enabling BLTouch and changing the settings.
I've seen it somewhere (I can't remember where) and I think it's correct, but if you go:
Motion -> Bed Levelling -> Level Bed, it should run an auto bed leveling sequence. The same should happen if you use G29.
If I use the control knob and LCD, my Ender 3 will level the bed manually. It does this by moving to one corner, you manually adjust the height using the knob and then move to another corner and repeat multiple times.
If you look in the Marlin source code:
/**
 * The "Manual Probe" provides a means to do "Auto" Bed Leveling without a probe.
 * Use G29 repeatedly, adjusting the Z height at each point with movement commands
 * or (with LCD_BED_LEVELING) the LCD controller.
 */
//#define PROBE_MANUALLY
//#define MANUAL_PROBE_START_Z 0.2

That is exactly what happens yet as you can see, it is commented out. If I run G29:
>>> G29
SENDING:G29
Mesh Bed Leveling has no data.

It confirms the fact that it wants me to do it manually because it is clearly trying to get previous mesh data rather than level the bed, which means I would have to do it manually.
I cannot find any other settings that would affect this, only what is already commented out, yet it still happens. Could anyone help out here?

Can you share the configuration files? Link e.g. to Pastebin.com for people to look for errors.

I have an SKR PRO that initially didn't allow to store your settings to EEPROM, this is now fixed by storage to flash drive when FLASH_EEPROM_EMULATION is enabled, this is default enabled for your board too, so, is the SD card present?

@0scar Hopefully mediafire will do! configs. And yes, the SD card is present and works correctly.

I feel like such an idiot. I was totally overlooking what type of mesh levelling it was doing. In config.h I hadn't enabled auto_bed_levlling_bilinear and it was just on the manual mesh level setting so it was doing it manually. Lesson learnt!


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Wanhao Duplicator i3 Mk2 Firmware Update
I have a Wanhao Duplicator i3 Plus Mk2. Its auto-leveling never worked properly since I bought it a year or two ago. I decided to upgrade the firmware to try and solve this problem. Unfortunately, I did not know I had a Mk2 when I started this process (I'm a photographer, it is only a Mk2 when it says so on the Camera housing which is seemingly not the case here, you needed to be fortunate to know it is a Mk2 if it has a Z probe). As such, I uploaded the wrong motherboard and LCD firmware (for i3 Plus not i3 Plus Mk2). When I switched on and tried to level, it started driving the nozzle into the bed which in retrospect is to be expected as the firmware is looking for a switch, not a probe. Once I realised what the problem was, I uploaded the Mk2 firmware but it seems uploading the non-Mk2 firmware has confused something somewhere so I can't get it to even be a printer anymore. The LCD is all mixed up with menus over one another and the printer does not react to anything. I tried to format the LCD with the image and procedure on Wanhao's site but this merely seems to exacerbate the problem.
Can anyone please guide me on how to start fresh and get the printer and LCD firmware restored so at least I have something resembling a printer again. The Wanhao customer support has been all but helpful and I've abandoned that channel as they simply email me the same firmware I already downloaded and used to get into this mess.

A quick Google search shows that there are multiple issues with updating to new firmware for printer and LCD (these are separate firmwares!). Useful links are this one and this one which have support for the MkII. Try if that works and update the question accordingly. Did you upload a hex file, or used PlatformIO or ArduinoIDE?

I uploaded a hex file. I will try and pursue the ArduinoIDE path as I have experience with that for Arduino boards.

Try to disconnect the display if you go down the Arduino route and see if you get it running while connected to serial (USB) and Pronterface for instance. When pursuing the Arduino route, be sure to send M502 and M500 after the flash to the printer to get the values from the firmware and overwrite the current stuff in the EEPROM.

My problem was resolved with the help of comments above.

A quick Google search shows that there are multiple issues with updating to new firmware for printer and LCD (these are separate firmwares!). Useful links are this one and this one which have support for the MkII....
Try to disconnect the display if you go down the Arduino route and see if you get it running while connected to serial (USB) and Pronterface for instance. When pursuing the Arduino route, be sure to send M502 and M500 after the flash to the printer to get the values from the firmware and overwrite the current stuff in the EEPROM.

I downloaded the Mk2 firmware from here and then used the normal Wanhao procedure to update both the motherboard and LCD and this left me with a working printer afterwards. Why the firmware downloaded from Wanhao's own site does not work is a mystery.


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Vertical 5 mm diameter hole comes out fine, but diagonal 3 mm holes keep collapsing
I am trying to 3D print an object from Shapeways. Confidentiality prevents me from sharing the actual STL files publicly, but what I can say is that it's a shape about 2 cm tall x 4 cm wide x 4 cm deep, and where the design specifies a vertical hole 5 mm in diameter, the hole comes out fine, but where the design specifies multiple holes 3 mm in diameter, passing diagonally through the shape (at a 45° angle with the ground), the holes seem to collapse (i.e. I can't see through them, and if I push a straightened paper clip through the hole, it's blocked). This has happened repeatedly (e.g. Shapeways offered to re-print some shapes for free when they came out defective, but this happened the second time too).
I am new to 3D printing and trying to figure out:

Is the hole more likely to "collapse" if it's diagonal rather than straight up and down? Is this because when the shape is being 3D printed, it's oriented exactly as shown in the design, and so before the 3D printing materials have fully solidified, the holes are more likely to be collapsed by gravity? Or does it have more to do with the diameter of the holes, and if I made the shape with 5 mm diagonal holes, they might not collapse?

The material I'm picking from Shapeways's options is "Black Natural Versatile Plastic". Are there other materials that are less likely to have this problem?

could you make a stand in model, for exampe a cube with the holes you describe? Is it SLS or FDM printed?

I had never heard of SLS or FDM.  I looked them up, but I still can't tell from Shapeways' checkout process which one they use when I order a print in "Versatile Plastic".  I asked customer support to find out. @Trish when you say "could you make a stand in model", do you mean make a design with the same types of holes in it, for the purpose of testing whether it has the same printing problems, and then if it does, I can share that STL file without violating the NDA?

A simple cube with just random holes does not allow to identify the project or item, but it helps to identify the possible print problem. A simple cube, same holes, no other features.

SLS is Selective Laser Sintering/smelting, where a laser melts a powder (usually nylon) to create 3D objects. FDM is Filament Deposition Modeling, where a plastic filament is melted and pushed through a nozzle. FDM is visibly made from layers, SLS from nylon is somewhat porous but layers can't be distinguished.

A member of the public on Stack Exchange's forum gave me the answer:
"The problem is not the hole 'collapsing' in and of itself. The problem is the material.
Versatile Plastic is a layered powder fused together with a laser in multiple layers, so the unused power has to come out from the various holes in the model once printing is completed. However, these layers are also very thin and compact. Therefore, if you make a small enough hole, the powder simply won't flow through it and it becomes stuck. Due to the small dimensions you listed (of said hole) it's gonna be difficult to free it due to the sheer compressing forces involved. When working with such fine details Versatile Plastic is not the most indicated material.
The only correction you can make to rectify the problem is changing material. Fine Detail Plastic would be a good choice for a new test, although it is not cheap compared to Versatile, is certainly cheaper than metals.
Fine Detail Plastic should provide you with a good result if you feel like trying it out."
ShapeWays technical support told me basically the same thing, and added that ordering the shape in black might also exacerbate the problem:
He said that when a model has holes in it, a human actually pokes the holes to get residual material out if possible.  Then he adds: "The last issue would be that Black indeed causes additional issues. If the production team isn't able to clean the model properly, or didn't do their work right, this could become and issue when we dye your model. All Versatile Plastic is printed in White, when selecting a colored finish such as black, we dye the model using a bath of regular RIT DYE. If the hole still has trapped powder, the bath will make the loose powder wet and make it become sticky, in combination with the dye this causes it to become chunky on the inside."
TL;DR: I can try to fix it by using Fine Detail Plastic, or I could try ordering in white and then painting it black myself to avoid gunking up the holes (the insides of the holes don't need to be painted black).

I had a suspicion that way, but without the information about the method (nylon powder SLS) I couldn't guess.


text:
How to print spiral(spring) static?
I have designed this model:

My goal is to make it static, no vulnarable to shakes.
The pitch is 40 mm with 4 revolutions. The dimensions of the 'wire' are 5x5 mm.
Which settings for printing should I use to archieve hardness? I plan to make the wire 5x10 mm height, 4 walls, 0.28 layer height, 0.5 nozzle size. PLA. I don't know if this is overkill or it will be useless.
I hope you can give me suggestions about printing settings and model dimensions.
I know that's spring design, which is made to be springy but I need it for other use.
Second design. Less springy, but not by much. My last hope is to print it horizontaly.

Can you clarify the 5x5 and 5x10 figures? Is this cross section of the spring with planes through z axis? Which is z direction and which is radial?

Also, note that with the many bounraries in the polymer, printed springs other than coil springs are exceptionally weak.

I added picture of the second design with 5x12 spiral.

What are you actually trying to do here? “Hardness” is not usually a spring characteristic.

I'm trying to do this: https://www.aliexpress.com/item/627016197.html

@SimeonSimeonov: That helps clarify a lot; can you add it to the question so that it's not missed by readers?

If you want an helicoidal object which acts relatively rigid, you should pick a plastic which is very rigid to begin with. In the case of 3D printing, probably PLA is the best choice. Make it as thick as you can in all the directions where you have no constraints.
Still, it's an object which will be hardly printable without dissolving support material. You need a two material 3D printer if you want to get good results.

You might manage with Tree Support

This answer is good for the question as asked, but possibly not for what OP actually needs. The clarifying comment that this is a vending machine auger indicates that ability to bend/compress by a few mm is unlikely to be a problem, and OP really should be asking about how to ensure it's not brittle/subject to breaking apart at the layers.

@Trish: Yes, tree support excels for things like this. Doing your own support structure would also be an option. I'd probably do it as an internal-threaded cylinder around the outside with sawtooth thread profile for the helix to rest on top of, with a few splits in it to make separation easy.


text:
Ender 3 Printer not printing @ center for reasons unknown
I know this issue has been asked countless times before, but I haven't been able to fix my specific Ender 3 printer. I have been looking virtually everywhere via Reddit and here for answers, but I really don't have a clue what's going on and how to fix it.
i got my printer a couple months ago but just started recently using it often. i managed to get it to print several things successfully, but after one specific print, my Ender 3 printer decided to "home" itself to the top left corner of the printer. normally my Ender 3 printer auto-homes to the bottom left corner. ever since that weird "homing" incident, my printer has been never printing things out correctly. here's what has been happening:

my prints are never in the center of the print bed anymore.
my printer would move its y-axis to move the test bed away from the front of the printer even though it already is. this causes the motor to stutter and the entire bed to not move.
my printer would start extruding material on the very edge of the bed.

i believe what's happening is that the printer believes that the bed is somewhere where it actually isn't. my printer for the most part knew that it was always "centered" at the bottom left of the print bed, but now it seems as though it thinks that it is now centered at the top left corner.
i hope this all makes sense; i've been looking into several solutions but really am worried that those solutions won't work out for me. i appreciate all help and advice. i am a complete noob to 3d printing and am really stuck. thanks in advance!

Connect it to a PC and send the "M119" command - this will give you the current readings of the endstops. Are those normal?
Do all axes move in the right directions when commanded to?

i have tried connecting it to a PC several times now, but it seems that my computer and Cura doesn't detect the printer. I'm not sure if it is an issue with my printer itself with a faulty port or if the USB is just old. any suggestions?

Did it work before? You may need to install CH340G drivers for it to be recognized. Does anything appear in the Device Manager when you connect to the board?


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Useless head movements in PrusaSlicer
I love PrusaSlicer but I am having a problem.
As you can see in the picture the head makes movements that seem useless
(blue lines that come out of the print in the corners and go back instantly in the object) and these make damages to the object during the print.

How to configure PrusaSlicer so that doesn't happen again ?
Thank you.
Edit : Thank you for your answers but I think we have a misunderstanding. I already have z-hop activated, the real problem is that the slicer makes the head move outside the print (that's what you can see on the first screenshot, every blue line crossing the print shouldn't exist).
I actually don't have this problem with curaengine on repetierhost as you can see in the following screenshot :

Try https://github.com/supermerill/SuperSlicer maybe it has implemented a different algorithm.

@FarO I found the solution but thank you for the link ! This fork seems very interesting (eg: it implements top surface ironing that works so well in curaengine)

I found the solution :
It was the option "avoid crossing perimeters" that seems to do exactly the contrary of what it means.
Thank you all for your answers.

you should approve your answer!

Enable Z-Hop. I don't know what the actual parameter is called but it should say something like "Z-Hop".

In PrusaSlicer 2.0, use the Filament Settings Tab, Filament Overrides entry.

Look for Lift Z, click the box, enter a suitable figure. 0.2 is a good place to start. You can raise it if needed, lower it to decrease (minimally) the overall print time.

Stringing should not be there in the first place... retraction maybe helps more?


text:
Thermal Runaway E1
I am currently building a Hypercube Evolution from a kit that was passed on to me. It uses a BIQU KFB2.0 control board and a 24 volt power supply. I have no prior experience in 3D printing.
I was getting to the end of the build. Everything was working. I was testing every component as I added it using Pronterface. I have not covered the aluminium heated bed with anything as I did not want to cause problems for the induction sensor (used as Z Min endstop). The induction sensor has a 4 mm range for ferrous metal and less for aluminium. I was intending to print on blue tape.
One website I visited suggested using feeler gauges as a better choice when levelling the bed. So I did. What I did not know is that both the hotend and the bed have power running to the outer surface. I found out when a feeler gauge touched the bed and the hotend at the same time. Since then, my LCD display gives the message "Thermal Runaway E1 press reset". I have pressed reset on the control board to no avail. Short press, long (5 and 10 seconds) and double press. None of which work. I have disconnected the hotend and it's thermistor from the control board. I have tried using another thermistor, but to no avail. Pronterface, when trying to connect, gives the following two lines:
"Error: Thermal Runaway, system stopped! Heater_ID: 0
Error: Printer halted, kill() called!"
I have disconnected all wires from the control board other than those leading to the LCD screen. The only power coming from the PSU. Still have the Thermal Runaway E1 error.
I have also re-compiled Marlin 2.0.6.1 using Auto Build Marlin and uploaded to the board, still the error persists. Anybody any idea how to fix this problem?

Can you disconnect the thermistor connector at the control board and measure its resistance at that connector with a multimeter? That will check if there is a broken connection somewhere in that part of the wiring.

You wrote "I found out when a feeler gauge touched the bed and the hotend at the same time." - what happened?

When the feeler gauge touched the hot end and the bed at the same time, I got a few pretty yellow sparks. This is when my problems started. The thermistor for the bed shows 137 kilo-ohms. The thermistor for the hotend showed 105 ohms. I removed the thermistor from the hotend and it now shows 110 kilo-ohms.

My limited knowledge suggests that there may be a short at the hotend. Would i be correct?
I have now removed all connections from the board, other than the stepper drivers and the LCD screen. When I connect to the computer, I still get the Thermal Runaway error on the screen.The powers supply was not connected.  Pronterface will not connect. However, I can still upload firmware to the board.
Have I fried my board and if so, will I need to replace the stepper drivers as well as the board?

Sounds like your hot end thermistor is shorted / damaged. Probably an issue with its insulation.
Try plugging the heated bed thermistor in the hot end thermistor port - does it read correctly then?

Sorry towe, I have now disconnected everything from the board other than the stepper motors and the LCD Screen. The board will not connect to Pronterface and the LCD screen just reads, Thermal Runaway Error: E1, Printer Halted, Reset. So, at the moment, I cannot check. I can upload firmware to the board, so we do have communication. I have taken a closer look at the thermistor head. On one side there is about 5mm of bare wire between the head and the insulation.

Sounds like the sparks indicated a temporary short that damaged something in your circuitry used for detecting thermal runaway.  That's the place to troubleshoot.

I found the solution. Controller board was broken, I had to order a new one.


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Why does Marlin report the wrong temperature until print is stopped?
I have an Ender 3 Pro with a Bigtree SKR board. I just replaced the entire hot end (thermistor, heating element, Micro Swiss hotend).
Now when I try to print a Benchy everything seems fine until maybe the 3rd or 4th layer. Then the PLA stops flowing so I stop the print and the temperature flies back up from 220 to 260 °C on its own (I do not want to print at 260 °C, I want to print at 220 °C). This makes me assume the PLA is stopping because the temperature is too hot.
What would cause this? Did I wreck the thermistor when I was putting it in? Is it a firmware issue? Why isn't runaway protection turning it off?

You print PLA at 260°C? What did you modify? Did you install the proper firmware in swapping the hotend? Installing firmware is not optional.

210-230 is most likely ABS and not PLA. PLA is 190-210.

The specs on the site you link read Print Temperature
190C - 220C
Plate Temperature
60 - 80C
Extruder Temperature
200C - 220C and are rather typical for PLA. the sticker 210-320 you quote however sounds ABS-y

Let us continue this discussion in chat.

@Tish reading back I see the problem, I am not printing at 260. The OS states it is at 220 but when I cancel it flies back up. I don't want it to print at 260 just to be clear.

@Jackie And your target temp is 220° all along? Sounds like a wonky thermistor, or perhaps excessive part cooling / unisolated heater block / terrible PID tune.

@towe my guess is the thermistor is the issue going to try and replace out later. Can you talk more about the unisolated heater block? Does that mean I didn't properly set the block with the grub screw? Also what is PID tuning?

@Jackie Depending on your part cooling fan, the air flow of that might directly hit your heater block and nozzle - cooling it down excessively, which could cause the lack of extrusion. The board tries to compensate for that by heating far more than would normally be required. When you then stop the print, the heat shoots up due to the previous heating.
The fix would be a better part cooling duct, or one of the silicone socks you can put over your heater block to better insulate it.
PID refers to how the controller board calculates how much to heat the nozzle to maintain a stable temperature.

You can tune those values if your temperature fluctuates greatly, but I don't think this is your (main) issue.

@towe interesting, could that be an issue if the silicon sock was slightly off? I did notice it was a little offset.


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Order in a line command in G-code
I've started learning G-code for 3D printing and I'm quite confused.
I'm using an Ultimaker S5 printer and the firmware is : 5.5.12 - 20200226-UltiBot

Is there a difference between G1 F1200 X188 Y92 E0.01 and G1 X188 Y92 F1200 E0.01?
Most of my code looks like: G1 X[coordinate] Y[coordinate] E[num] without Z!
How is this possible?! My model is a 3D-model so how come the letter Z appears about 5 times in tens of papers?

Any help would be greatly appreciated!

I haven't used every flavor of gcode or firmware, but I've never seen the parameter order be important, provided that:

The G or M code was the initial entry; and

Each parameter was clearly listed with one or more spaces between parameters; and

No spaces were in between the parameter letter and the value.

We use a custom version of Repetier firmware to run 3D printers and Fadal CNC machines, and in every use  G1 F1200 X188 Y92 E0.01 would be evaluated and executed completely identically to G1 X188 Y92 F1200 E0.01
Nearly all gocde variable values are persistent, so if Z remains unchanged because it is only specified once per layer, or if Z remains unchanged because it is explicitly specified (with the same value) on every line, there should be no difference in the behavior of the printer.

To expand a little on @Davo's answer. Any parameter that is omitted but required for movement is assumed by the g-code interpreter to have the same value in the state machine as when it was last provided. This is true for F, X, Y and Z. If the op wants to go hardcore though: https://www.nist.gov/publications/nist-rs274ngc-interpreter-version-3

@user77232 And E! (then it will be a move without extrusion) See the G0-G1 sources. A parser is used to parse the arguments of a command, the seen method is used to determine if a parameter is specified in the G-code command (whatever the position is), if not, the already set one from previous commands is used.


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Design of hotend of Monoprice MP Select printer
I am not an expert and I may use slightly wrong terminology here.  Please assume I have used the incorrect term if something I say does not quite add up. I have a Monoprice MP Select printer which had some PLA go brittle and really jam up the feed in the hot-end.
While trying to clear the hotend - including removing stuff from inside the hotend heatsink a small, dark grey/black, round washer with outer diameter of about 5 mm fell out the bottom of the machine.  I'm scratching my head as to where, if anywhere this belongs on the machine.  It is entirely likely that this is not from the hot-end but fell off a pocket tool I was using without me noticing.  Does anyone know if there are any small washers associated with the hotend?
I ask if anyone knows if this is part of the printer because subsequent to my clearing the head, the printer is not printing properly - everything still works - kind-of - just prints are messier.   I initially had problems with getting the print to stick to the bed at all until I readjusted the bed - something I have not had to do before, and I'm unsure why I would suddenly need to.   I'm posit it could simply relate to pressure  I may have inadvertently applied while clearing the hotend and the fairly fine tolerances, but I don't know enough to know if it is actually due to a missing part!

Additionally, I've been unable to find an explosion/tear-down/parts visualisation for this printer or hot end - if anyone knows of any that would be very useful, although that's not my question.

What is the inner diameter? 3 mm?

photos of the hotend and the washer might help.


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What is the best way in SketchUp to align the bottoms of all objects to the x-y origin plane?
A single object slices OK in Slic3r.  However, when I copy the objects and paste onto a guide point on the y axis to put five objects in the drawing, the slicing leaves out parts.  The worst object is below the y-axis by 0.01 mm, but SketchUp is not allowing me to move the object to the y-axis alignment.  I've tried decreasing the snapping length to 0.000001 mm, and even unchecking Enable length snapping. I'm looking for the best way to align the bottoms of all objects to the x-y origin plane.

I would like a better answer involving automatic alignment, but this was my solution.

Make the object a single component.
Make sure the guide points are accurately located.
Cut and copy the first component to the origin.
Copy the component to the guide points.

What also worked better was to break the grouping of components into building blocks that could be put together to make the whole.  Once the building block sliced correctly, it could be made into a component.
Note: the more complex the first layer, the more this accuracy seems to be an issue.

Hey Perry, this would be better as part of your question.

Due to lack of response, I expect this to be the answer, but want it to be open ended.


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Hotend not heating
I've a problem with my BQ i3 Hephestos.
I've noticed that in the last few prints that I've experienced some temperature drops every now and then. Yesterday, after 3 of a 4 hours long print, the hotend completely cooled down (I have Octoprint and from the temperature graph it was visible the exponential decrease to 25 °C). Apart from realizing that, evidently, I have not any cold extrusion prevention set up on my Marlin firmware (I'll surely fix that asap), yesterday I've shut everything down with the idea to try again today.
This morning, though, I could not start my print because the heater didn't even warm up.
After disassembling the hotend I've tried the following things:

I've tested the thermocouple putting it near the heated bed and it measures the correct value
with a tester I've measured the voltage that goes into the resistance ($\approx 12\ V$)
I've measured the resistance with the tester ($\approx 3\ \Omega$)

I've also noticed that while $12\ V$ is the voltage that the printer sends to the resistance, measured when the resistance is not attached to it, if I repeat the measurement with the resistance attached to the printer I get a few $mV$. I really don't know whether it is the expected behavior or not.

Further inspection...
Trying to inspect the cables better I've noticed a black spot on the connector of my Ramps 1.4 board (as you can see in the attached image).

At this point I think I may have damaged something with too much current/too much heat. Too much current it seems strange to me because I have never changed anything in that sense, It is exactly the same as when I have bought the printer. It may be something related to the heat as the problem firstly occurred only on long prints (some hours).
I don't know if this clarify something to you, but to me it says almost nothing...

UPDATE
I've tried to attach the heater again to its original place and now it seems to work (in the sense that it gets hot). I've initially set the temperature to 60 °C, and it had no problem reaching and keeping it. Then I've tried to raise it to 180 °C but I had to shut down the heater after a few seconds because the cables became very hot and tender and it smelled of burnt

The suddon drop and it continuing to print also says, that you don't have Thermal Runaway Protection on! Please fix that ASAP and don't operate your printer till you did.

Since your heater functions with a load, but the power circuitry to the heater does not, it sounds the the circuitry can't supply the current the heater needs. That is assuming you did not change out the resistive heating element lately.

@Trish Thanks for the advice, I will surely fix that before trying to print again

@PerryWebb I have not changed anything on the hotend since i have the printer (a couple of years). Can you suggested me how to check if the current is enough? With the tester I can measure the current with the resistance not attached, but I don't how much should it be. Thanks a lot

A 40 W heater at 12 V will draw about 2 A of current. Since you see burn marks, it could imply that the wires aren't screwed in properly. You cannot measure the current without a load (heating element is a resistor) present, current is measured in series, voltage in parallel.

Hi @Oscar, thanks for the reply. I've checked the wires and I think they were properly screwed in the connector, but I can't judge. Do you have any suggestion about how to fix the printer?

I've tried to directly attach the heater to the hotbed power supply (12 V as well) and I saw it works, so maybe it is something related to the ramps board :(

Where's a possibility: https://3dprinting.stackexchange.com/questions/10695/proper-hotend-heater-for-reprap-x400-pro-v3

I hope you can measure the resistance of the cables and the heater cartridge, then you can work out the math for calculating the current. But if cables get hot, not warm and begin to smell, then you need to change the lot. RAMPS boards are becoming obsolete, you could opt for a new controller board and rewire the hotend and bed.

Hi @PerryWebb, thanks for the reply. I will definitely give it a read!

@Oscar I've measured the resistance of the system cables + heater cartridge and it's 3.1Ω. Since for the tension I get 12.2V, the power is P = V^2/R = 48W. From the internet, I read that the cartridge I have is a 12V 40W one. Could the 8W more I measure be responsible for the overheating of the cables near the connector? Just to try I've exchanged the heater and the fan on the board and it reached 200°C without smelling

And I = 12 / 3.1 = 3.9 A. So, are the cables you used up to that current?

I really don't know, I've never changed them in over 2 years. I have ever assumed they are since they are the cables shipped with the printer. In each case they are a little thicker than a normal jumper. To be sure, though, this evening I try to ask the vendor

In the end it turned to be that the RAMPS board was ruined.
I bought a new RAMPS board and it worked immediately.


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TMC2208,BMG and 0.9 degree stepper motor, is this a bad combination?
My printer randomly freezes partway into the print whenever I use the combination of Marlin 2.0, TMC2208 stealthchop, a 3:1 geared extruder and an E3D 0.9° stepper in a Bowden configuration on the E axis.
Is this a reasonable combination that other people have got working or is it too high of a step count (830 steps/mm) for this particular driver? If I change one of these factors it prints normally but not when they are all used together.

Hi welcome to 3DPrinting.SE! Maybe you could add your controller board make and model, printer type, e.g. Delta or i3?

Cross post?


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How to slice rounded corners in thin walls with Cura
I'm trying to print a small box with 1 mm thick walls.
The box has rounded corners.
Cura slices the rounded corners with straight internal lines instead of rounded lines:

The reason for these straight lines is that Cura is using infill to fill the walls, because it determines that there's not enough space in a 1 mm wall for three 0.4 mm passes.

This causes the walls to have small imperfections in the final print.
I was able to solve this by increasing the model wall thickness to 1.2 mm (to allow for 3 0.4 mm lines), but even then it wasn't doing it as a single continuous line, but instead breaking it into short lines at the corner:

Is there a way to avoid this issue without increasing the wall thickness, and have 3 continuous lines?

I migrated to a good slicer after having to deal with those things in Cura.

@towe What slicer would you recommend to use instead?

I'm currently using SuperSlicer (based on PrusaSlicer) and am quite happy with it. You do lose tree supports though.

@towe The question is if this is a slicer related problem or a geometry related problem. I wonder how your slicer would tackle the issue with a 1 mm wall thickness while having a 0.4 mm nozzle. Interesting question, I'm interested in an elaborate answer. :-)

@0scar actually it is a model problem - the walls in rounded corners get closer than in straight lines as they are pretty much attempting an infinitesimal solution, which puts the walls a tad closer together in the center between two walls in those areas.

@towe that is not an error of the slicer, it is one of the .stl format demanding that the model has only flat triangle surfaces and the quality of the export. There are workarounds though.

@0scar Not a geometry problem, at least not for proper slicers. Answer inbound :)

Fixing the model
My solution to this problem is, to increase the thickness in such corners by 0.05 mm by pushing the inner wall's radius towards its center. This allows some extra space as a round corner is not actually saved round but as a pattern of straight wall facets, and those can get squished together just enough to make the slicer believe the wall is too thin for a proper wall. As you see, the new corner rounding starts a little bit before the outer one - in this exaggerated model I use 1 millimeter extra - violet are the normal corners 10 mm apart, black is the new inner corner, the light blue area between them is the extra bulk that will massively reduce the problem.

origin of the error
As an example, let's put the number of facets to 1 and 2 when we form them from the rounded corner. The more facets there are, the closer the distance between the walls will get to the full wall thickness, but it will always stay a fraction below.

How does the model fix work?
Well, we shifted the inner corner away, and with 2 facets we get a fidelity to the intended wall thickness of 96.21 % instead of 92.39 % for the non-modified wall - and with even more facets the fidelity gets better more quickly. However, there is a point where your gaps will start to diverge in the corner, so just using a tiny alteration is advisable - in our model case, 9 facets (a 10°) is the point where the inner wall will start to become more distant to the outer wall. That's why I only need such a tiny bit of extra space if I export the model with the most fidelity in the .stl generation my CAD has available.

making it work in the slicer
Another thing I do when I can't alter the model is, knowing that I usually slice width a line width of 0.45 mm. In case such a corner appears, I can then alter my line width in the slicer down to 0.44[5] mm (or more) and get pretty much the same result at the cost of possibly needing to account for errors in other areas.

Changing the line width fixes some corners, but causes this issue to appear in layers that were previously OK. Can you elaborate on how to increase the thickness of the corners? Do you mean in the model itself?

@YoavKadosh Added a picture. In the model itself you alter the inner diameter a tiny bit. Technically you increase the inner diameter and push it's centerpoint away from the corner. This can be most easily be done by using a Push/Pull on the inside of the corner.

Contrary to the other answer, this is not (exclusively) a model / geometry issue.
Frame challenge: There's no good / easy solution to this when using Cura, at least that I know of. Better slicers can easily handle this situation though.
I replicated all the tests in SuperSlicer, which is a PrusaSlicer branch.
All tests were done with models with relatively high resolution:

As well as a model which I created to replicate a horrible quality .stl:

I checked the continuity of the added internal line with Simplify3D's g-code preview.
For a 0.4 mm extrusion width and a 1 mm wall thickness, PrusaSlicer simply adds a 0.2 mm line in the middle. This line is completely uninterrupted:

The same happens with the very rough .stl:

The same thing happens when using a 1.2 mm wall thickness:

Conclusion: You should not be adding esoteric "fixes" to your models to prop up terrible slicer performance.

Technically you use a Slic3r branch then.

@Trish Correct, though Slic3r itself has become obsolete.


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Connecting (Anet A8) 2004 display to MKS GEN L V2.0
Although it seems this question has been answered before Connecting (Anet A8) 2004 display to MKS GEN L this one differs because the v2.0 board has no obvious AUX-2 connector.
So the question is, how can I connect the Anet A8 LCD Panel (with buttons) to the MKS Gen L V2.0 board? Or where can I find the schematics?

Hi and welcome! Thanks for posting a separate question! Note that it probably can be done, but not if you are using the UART, since there is no AUX-2 (and the LCD you want to connect requires analog pins) you need to "harvest" them from elsewhere unused pins. This includes changing your pins_xxx.h file. It is much easier to buy a new LCD that works with the EXP-1/2 ports.

Thanks Oscar for your buying advice. As you might know the challenge of fixing what you have often predominates good sense :-). I will think about harvesting or buying ...

It probably can be done, but, it requires some splicing of your LCD cables (or using some Dupont male-female cables) and altering of the firmware pins header files.
The MKS GEN L v2.0 lacks the AUX-2 port that is present on the v1.0 controller boards. The reason for this is that they implemented support for more modern stepper drivers like the trinamic drivers that are capable of using UART to set stepper options.
The old v1.0 pin layout is displayed below:

The new v2.0 pin layout is dislayed below:

The Anet A8 2004 graphical display (so-called ZONESTAR_LCD) uses (at least one as the buttons are suited with different resistors) analog pin that is used to detect which buttons are pushed.
#elif ENABLED(ZONESTAR_LCD)
  #define ADC_KEYPAD_PIN 12

Pins A5 and A9-12, D40, D42 and D44 are used according to the pin layout.
In the pins_RAMPS.h header file the display usage is coded as:
#elif ENABLED(ZONESTAR_LCD)

  #define LCD_PINS_RS                     64
  #define LCD_PINS_ENABLE                 44
  #define LCD_PINS_D4                     63
  #define LCD_PINS_D5                     40
  #define LCD_PINS_D6                     42
  #define LCD_PINS_D7                     65

In order for this to work on the MKS GEN L v2.0, you need to source for free pins that can mimic these pins and alter the header file and create a spliced LCD cable.
It might be much easier to buy a new reprap discount display controller for about 10 bucks/euros and connect it to the dedicated EXP1/2 headers. Stay away from the Anet A6 graphical display.

Thanks Oscar! The dices have chosen to buy one (done). Anyway, your valued answer gave me confidence about modding the board.

The keypad of the Anet A8 just uses one analog pin. In the pins_RAMPS.h file the is further down the definition #elif ENABLED(ZONESTAR_LCD) #define ADC_KEYPAD_PIN 12. The buttons are suited with different resistors. So using your answer and this hint will help to get it running. Finding some time next week I will try to set it up despite my purchase.


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Extruder motor not running when using G-code from PrusaSlicer with non Prusa printer
I just assembled an FLSUN QQ-S pro printer and successfully printed two models from the supplied SD card. Everything works fine. However, I tried slicing my own model using PrusaSlicer and although the print head moves, the extruder motor does nothing. What could be the issue? Do I need to modify the G-code commands?

Is this a single-head (max) printer? Does your gcode have a T# argument, to direct extrusion commands to a particular head?

It is a single head printer.

Do you see extruder movement G-codes in the file? e.g. lines with G1 X... Y... E...

I solved the problem. The initialization code generated by the slicer wouldn't work with my machine. I replaced it with the init code from one of the test files.

Despite being solved, I want to note, that this was probaly due to using wrong extruder positioning. Prusa printers use relative positioning, whereas othe printers may use absolute positioning. I do not see any pros or cons for one or the other. Both the printer and the slicer can be configured to use either of them. In your case, it was probably that the printer was expecting absolute coordinates and the slicer was feeding relative coordinates resulting in no or very little movement. The configuration ussually happens at the start of the gcode by giving commands: M82 (abs) and M83 (rel).


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Got "Heating failed" error while heat catridge is working
I bought an Anet A8 Plus in January. Everything worked pretty well until one week ago. When I tried to print something, I got a "Heating Failed" error, as the hotend didn't get hot. I've made some search on the web, and I tried to use the bed connector on my motherboard, and the cartridge started to head. So I connected the hotend heater again to the hotend connectors.
I conclude the hotend connector may be broken, but this morning, it succeeded to heat my hotend (and then didn't work again). Can someone help me to understand what's wrong with it?

I also noticed that a LED power off when the cartridge's wires are connected (the D8 LED)

"heating failed" is Thermal Runaway Protection afaik. Did you test your thermosensor on the hotend?

This occurs when the hotend does not heat up as expected. It can be caused by many things: broken heater or thermistor wires, loose connectors, faulty heater or thermistor, a crack in the main board (broken copper path on the board). You have a lot of troubleshooting ahead of you. I suggest not printing with it until you have everything sorted out. It is a fire hazard especially with those Anet printers. They have a reputation of being quite flammable due to poor connections of the electronics.

Does your heater use this type connector? https://3dprinting.stackexchange.com/questions/10695/proper-hotend-heater-for-reprap-x400-pro-v3

authors: Сергей Казаку


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Anycubic i3 MEGA not heating past 140 ºC
[SOLVED] on [EDIT 3]
I just finished changing my i3 Mega's PTFE tube and brass nozzle, reassembled it, always taking care not to damage the heating element and thermistor wires.
Then I check the temperature and it was cooling down, despite the set temperature being higher (210 ºC). I turned it off, let it cool down and turned it back on. I set it again to 210 ºC and it only reaches about 135 ºC-140 ºC, not going over it.
So I change the heating element and thermistor for fresh new ones (original ones, that came with the printer) and the same behavior takes place: not heating up beyond 140 ºC.
Any ideas on why this is happening or how to fix it? I checked the connectors and they all seem to be fine. Cooling fans run normally as well.
Printer: Anycubic i3 MEGA. All stock parts, except the new nozzle (standard brass nozzle) and the PTFE tube (a blue one with 1.9 mm internal diameter). I'm setting the temperatures through the printer's interface, as I have always done.
[EDIT]
I did check some stuff with the multimeter and what I got is that:

The cables leading to the print head are fine;
The heating element's voltage is correct and the MOSFET seems to be
working fine both by checking the voltage and from the LED that
lights up when it is sending current to the HE;
The resistance of the HE is correct as well;

Form that, I am guessing the problem is the current fed to the HE. Later today I will try to heat both the nozzle and the bed to the (safe) max temperatures and see if the bed heating is problematic too. If so, the problem should be related to current.
If anyone has any other ideas, they are appreciated! :)
[EDIT2]
Heating up the print bed and the hotend at the same time didn't affect the bed at all. It heated up at the same pace as usual. Since the cables are fine, it shouldn't be a problem related to the power supply.
So I'm gessing the problem is the motherboard (Trigorilla 1.1). It didn't seem to have any burned components at a glance but I'm gonna check with a multimeter.
[EDIT3]
Turns out I messed up the heatbreaker, so the heatsink was cooling the hotend way too much... This is one way of learning I need to be careful with the heatbreaker, I guess. I'll leave a solution here for the newbies like me that end up in a similar situation.

Hi welcome to 3DPrinting.SE! Do you have a multimeter/tester to check the voltage and resistance of the heater element? Did you upload new firmware? Please look into phrase "Then I check the temperature and it was cooling down, despite the set temperature being higher", I don't understand what is meant here.

Any chance you put a 24 V heater on a 12 V system? Have you used an alternative method to measure the heater temperature?

If the voltage is correct and the resistance of the heater cartridge is correct, the current is a direct derivative ( I = U/R ). Is the heater cartridge making good contact to the heater block?

Yeah, the heater cartridge is touching the block nicely

@0scar I meant the nozzle was set to 210C and it eventually started dropping below 210C and not heating back up

So it did reach 210 °C once, but it could not maintain temperature and dropped to 140 °C?

There is a part of the extrusion ensemble called heatbreaker, responsible for sepparating the hot- and cold-ends. The problem is that I screwed the heatbreak up into the cold-end heatsinks and the heated block was now touching it. This made it cool off way too hard.
The solution was switching to a new, undamaged cold+hotend.

I recently had similar problem with my Prusa i3 MK2.5. It was not able to maintain the set tempereature. I measured the heater catridge (which was new) and its resistance was correct (about 4 ohms). So I changed the hotend MOSFET on the stock board with no result. So I changed the heater catridge for the older one and the issue was gone.
Since you have changed the heater, it is unlikely that you have multiple bad ones. Thus the only thing that remains is the MOSFET and the power supply. Make sure your power supply is stable under load and can deliver enough current.
More likely it is the MOSFET. It behaves like a resistor in the path for the current. If it is swithced off, it is like a large resistor (units or tens of megaohms) in series therefore no or very little current can flow. If it is switched on (units or tens of milliohms) the resistance is very small allowing the current to flow through the heater. If a MOSFET is bad, when it is switched on it can have higher resistance (units of ohms) and thus limiting the current and creating a voltage divider. Which you can measure.
You have to get to the bare wires that lead to the heater. Turn on the heater. Place your voltmeter lead on one wire and the other lead on the otehr wire. The voltemeter should show voltage close to your power supply voltage. If it is showing less, the MOSFET is bad and needs replacing.
For that you will need soldering tools and skills. You probably have an SMD MOSFET soldered directly to the board. I suggest removing it and replacing it with a THT MOSFET that you would place separately from the board with its own heatsink. When on the board, the board acts as a heatsink.
If you cannot do that yourself, ask someone to do it for you.
Before replacing the MOSFET, find whether it is a n-channel or p-channel MOSFET. It will most likely be an n-channel MOSFET but make sure it is.
If you replace it with THT MOSFET I would suggest these two: IRFZ44N (n-channel) or IRF4905 (p-channel). They are general purpose MOSFETs and should work well enough for drop-in replacement.
If it is not the MOSFET, power supply or the heater, then I have no idea.
You should be able to trace one of these loops:
power supply -> (fuse ->) heater -> n-channel MOSFET -> power supply
power supply -> (fuse ->) p-channel MOSFET -> heater -> power supply
Most likely will be the first loop.
NOTE: Checking the heater resistance might help but does not have to. At room temperature the resistance might be within limits (as with mine example) and when heated up the resistance increases with temperature and thus limiting the current. You would have to measure the resistance when heated up and disconnected from all circuits. (Heat up -> disconnect heater -> measure -> cooldown).
Hope that helps and good luck.

What about measuring the voltage and current on the heater when it is powered up.  If the MOSFET is the issue and the heater didn't reach temperature, the voltage will be too low.  The resistance of the heater will be R=V/I.  Thus if the heater resistance is too high, the current will be low if not reaching temperature. At 70 ºC below the set point, the power to the heater should be open loop (maximum voltage).

I have already suggested measuring voltage accross heater when powered up. That is (probably) the only way to check a MOSFET when in circuit. I also described measuring the heater resistance when heated up, or as you suggest, one can calculate it. But neither approach can give a deffinitive answer. The resistance will always raise with raising temperature. But can you say how much it should and how much is too much? You could say that only when comparing with another heater of the same type that is fully functional.

The heater at temperature should be approximately R = (V^2)/P.  So a 12V 40W heater should be about 3.6Ω, a 12V 30W heater 4.8Ω, 24V 40W 14.4Ω, 24V 30W 19.2Ω.

Again, the resistance raises with raising temperature therefore, the maximum power of the heater decreases. One can either heat up the heater as much as it can go, disconnect it and measure the resitance with multimeter, or heat up the heater as much as it can go and then measure the voltage and current and calculate the resistance. Neither approach gives you an answer whether the heater is faulty, unless you have the datasheet of the heater or you can compare the values with a fully functional heater of the same type.

@MStarha I did some new checks (on the edit of the original post). Thanks for the directions for troubleshooting!


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What is the maximum length of the TMC drivers signal wires?
I would like to place the TMC drivers (the stepsticks modules, in fact) on the side of my controller board for easier cooling.
What is the maximum length of the data wires? Specifically, Step and UART, the other ones should not pose any problem.
In my case I would extend them by about 10 cm.

10 cm would be fine. That's the short answer, the real answer is that it depends on the UART speed and the exact conditions that you will be extending them. If you expect noise feedback from the motor coils inducing voltages into the UART lines, then perhaps they should be shorter. Keep the high current wires and the signal (UART) in separate places if possible. Also if you can use a shielded cable (e.g. and old shielded USB cable) then you could get away with a meter thereabout.

Should the shielding go to the negative rail of the controller board, or to a separate earth ground? I have both. The idea of USB cables is good, I have plenty of them. I could use one cable for STEP/UART one for DIR/ENABLE, and leave only motor and electronics power outside. I guess that DIR/ENABLE would not need shielding but it shouldn't hurt.

Yes, the shielding should go to what you are calling the negative rail (otherwise known as GND). DIR/ENABLE are just logic signals so yes they should be fine.

Even a few meters should be just fine. I believe Marlin uses 115200 to communicate with UART drivers.