Getting jams caused by what I think may be heat creep  

Re: Getting jams caused by what I think may be heat creep

Prusa support had me downgrade to v3.1.3 firmware and I'm doing some tests now. I picked up an IR Thermometer to measure the temperature of the Extruder motor. After downgrading I decided to do a benchmark with a Benchy. During that print I got temps of anywhere from 120F (49C) to 127F (53C) for the extruder motor. Going to try printing a few more things and measure the temp of the motor some more. It was literally uncomfortable to touch. Also the smokestack on the Benchy came out a bit wobbly looking, presumably from the extra heat I think. First time I've seen that in my tests. The previous tests wi v3.3.0 firmware did not do that.

Anyway, just an update after hearing from Prusa. Will keep testing and give some more results. Going to start a 10 hour print in a bit and see how it goes.

Re: Getting jams caused by what I think may be heat creep

[...] I don't have a smooth rod like that I can slide up through there. I can look for something like that, but wouldn't a piece of filament work, too? I could try that. If I do get a hold of a smooth rod, what can be done if the motor's hobbed gear is in the path?
Filament is OK for a test, but can flex and bend a bit. You can try your 1.5mm hex wrench to check part of the path.

Re: Getting jams caused by what I think may be heat creep

[...] I don't have a smooth rod like that I can slide up through there. I can look for something like that, but wouldn't a piece of filament work, too? I could try that. If I do get a hold of a smooth rod, what can be done if the motor's hobbed gear is in the path?
Filament is OK for a test, but can flex and bend a bit. You can try your 1.5mm hex wrench to check part of the path.

OK. I can do that later when this print finishes... that said, I'm still left with this question from my post... If I do get a hold of a smooth rod (or use my hex key), what can be done if the motor's hobbed gear is in the path? The motor obviously can't be moved from its location, right? So what's the solution if that ends up being a problem?

Re: Getting jams caused by what I think may be heat creep

[...] OK. I can do that later when this print finishes... that said, I'm still left with this question from my post... If I do get a hold of a smooth rod (or use my hex key), what can be done if the motor's hobbed gear is in the path? The motor obviously can't be moved from its location, right? So what's the solution if that ends up being a problem?
It will be important information for support. Looking at Step 15 in the assembly instructions, you should be able to do some adjustment. Look at the 2nd picture in that step.

Re: Getting jams caused by what I think may be heat creep

[...] OK. I can do that later when this print finishes... that said, I'm still left with this question from my post... If I do get a hold of a smooth rod (or use my hex key), what can be done if the motor's hobbed gear is in the path? The motor obviously can't be moved from its location, right? So what's the solution if that ends up being a problem?
It will be important information for support. Looking at Step 15 in the assembly instructions, you should be able to do some adjustment. Look at the 2nd picture in that step.

If you mean is the gear in alignment with the PTFE tubes on the top and bottom of it, and the filament is directly in the middle of it, then yes. The gear is properly aligned. That I've done early on and rechecked each time I reassembled it. I thought you meant moving the motor and its post (which has the bondtech gear on it) to the side so it provides more room for the filament path. I have done Step 15 many times and looking at it right now it is lined up .

Re: Getting jams caused by what I think may be heat creep

Anyone have a thermometer and can tell me the temp of their extruder motor after running for a couple of hours? Mine is sitting around 125-128F (52-53C).

Re: Getting jams caused by what I think may be heat creep

Anyone have a thermometer and can tell me the temp of their extruder motor after running for a couple of hours? Mine is sitting around 125-128F (52-53C).
No thermometer, but mine's been running a detailed print for about 3 hours and placing my thumb on the extruder feels like the sidewalk on a warm spring day. Not hot at all.

Re: Getting jams caused by what I think may be heat creep

Anyone have a thermometer and can tell me the temp of their extruder motor after running for a couple of hours? Mine is sitting around 125-128F (52-53C).
No thermometer, but mine's been running a detailed print for about 3 hours and placing my thumb on the extruder feels like the sidewalk on a warm spring day. Not hot at all.

Crazy. Mine feels like a skillet.

Re: Getting jams caused by what I think may be heat creep

After reverting to firmware v3.1.3 as Prusa support requested of me I did some documentation as I printed this STL (includes STL and gcode: https://d.pr/f/YiSAw8 ). Measured temperature of the extruder motor throughout the print. While the print did finish, it definitely had problems. Lots of clicking of the extruder gears and high temps on the extruder motor (in my opinion). Here are my results:

I think it did better than in the past, but I attribute that with the Sunon fan I installed to replace the Noctua in an effort to fix the flaws of this printer.

Less happy each day with this printer.

Re: Getting jams caused by what I think may be heat creep

After reverting to firmware v3.1.3 as Prusa support requested of me I did some documentation as I printed this STL (includes STL and gcode: https://d.pr/f/YiSAw8 ). Measured temperature of the extruder motor throughout the print. While the print did finish, it definitely had problems. Lots of clicking of the extruder gears and high temps on the extruder motor (in my opinion). I'm really surprised to see your temps. I lived in Phoenix where the outdoor temps were routinely over 50C/122F and don't consider that hot for machinery. I know my car interior was routinely 150F/65C as attested to by my burnt fingers on the steering wheel. 113F/40C is within the range for ambient temps for non-industrial equipment. The equipment itself will be hotter of course. I don't have a thermometer handy for measuring my extruder temps, but those temps sound about right. I'm certainly not scalding my thumb when pressing it on the extruder motor mid-print.

I looked through your gcode file and don't see anything unusual. Are the extruder clicks accompanied by actual print problems? Your speeds aren't fast enough to cause the usual infill problems I've encountered, but retractions do make a little noise. You can tune this with retraction speeds (yours are 35mm/s) and de-retraction speed. I've read that de-retraction speeds should be slower so am experimenting with 25mm/s. I sometimes get a soft "tock" sound when playing with settings but that's about it.

32-45mm is where the "shoulder" of your part prints. Looking at your table, it seems that's the only area you're hearing the clicks. Looking at the gcode, you can see a transition from 2 perimeters to a dense zig-zag pattern in this area (see pic below). I suspect that's producing the noise you're hearing. There aren't a lot of retractions, but that pattern is going to cause a staccato machine-gun of activity. What is happening is that you are printing relatively thin walls and the slicer is generating "shelf" material for the next sloping layer to rest on. If I load that STL into Slic3r and increase perimeters to 3 or 4, it's easy to eliminate that pattern at the shoulder. That should make the print much quieter and result in a much stronger part.

Do you have an extruder visualizer mounted? Is the extruder actually reversing when the noise happens, or steadily advancing? I'd expect a racket in these areas due to rapid movement, but not retractions. Try increasing perimeters to see if it helps. You can slice the model down to only the shoulder part to avoid printing the entire thing.

Less happy each day with this printer.Well... You've printed a large part and are only having "noise" on part. Unless it's failing, I wouldn't consider the noise resulting from that sort of movement to be a problem. It looks like slicer settings may help with the noisy part of your problems.

Re: Getting jams caused by what I think may be heat creep

After reverting to firmware v3.1.3 as Prusa support requested of me I did some documentation as I printed this STL (includes STL and gcode: https://d.pr/f/YiSAw8 ). Measured temperature of the extruder motor throughout the print. While the print did finish, it definitely had problems. Lots of clicking of the extruder gears and high temps on the extruder motor (in my opinion). I'm really surprised to see your temps. I lived in Phoenix where the outdoor temps were routinely over 50C/122F and don't consider that hot for machinery. I know my car interior was routinely 150F/65C as attested to by my burnt fingers on the steering wheel. 113F/40C is within the range for ambient temps for non-industrial equipment. The equipment itself will be hotter of course. I don't have a thermometer handy for measuring my extruder temps, but those temps sound about right. I'm certainly not scalding my thumb when pressing it on the extruder motor mid-print.

I looked through your gcode file and don't see anything unusual. Are the extruder clicks accompanied by actual print problems? Your speeds aren't fast enough to cause the usual infill problems I've encountered, but retractions do make a little noise. You can tune this with retraction speeds (yours are 35mm/s) and de-retraction speed. I've read that de-retraction speeds should be slower so am experimenting with 25mm/s. I sometimes get a soft "tock" sound when playing with settings but that's about it.

32-45mm is where the "shoulder" of your part prints. Looking at your table, it seems that's the only area you're hearing the clicks. Looking at the gcode, you can see a transition from 2 perimeters to a dense zig-zag pattern in this area (see pic below). I suspect that's producing the noise you're hearing. There aren't a lot of retractions, but that pattern is going to cause a staccato machine-gun of activity. What is happening is that you are printing relatively thin walls and the slicer is generating "shelf" material for the next sloping layer to rest on. If I load that STL into Slic3r and increase perimeters to 3 or 4, it's easy to eliminate that pattern at the shoulder. That should make the print much quieter and result in a much stronger part.

Do you have an extruder visualizer mounted? Is the extruder actually reversing when the noise happens, or steadily advancing? I'd expect a racket in these areas due to rapid movement, but not retractions. Try increasing perimeters to see if it helps. You can slice the model down to only the shoulder part to avoid printing the entire thing.

Less happy each day with this printer.Well... You've printed a large part and are only having "noise" on part. Unless it's failing, I wouldn't consider the noise resulting from that sort of movement to be a problem. It looks like slicer settings may help with the noisy part of your problems.

I suspect you may have missed this part of my last post:

While the print did finish, it definitely had problems. Lots of clicking of the extruder gears and high temps on the extruder motor (in my opinion)

There are gaps in the perimeters as well as a LOT of gaps in the top (and even some in the bottom) layers. Before I started I did a cold pull, that came out perfectly clean, and then fired up my print. As for the sounds emanating from the printer. The extruder clicks and sound of grinding filament are distinctly different than the sounds of rapid retractions. I may not be an expert, but I can tell the difference there after printing for two years. In addition you can watch the extruder gears jump as they click from not being able to push plastic downward. I do appreciate your help, and I am glad you're having luck with your MK3, but it is unfortunately not the case here.

Re: Getting jams caused by what I think may be heat creep

Just re-read this thread, and didn't see mention of layer issues. Thought you were having concerns about temps and sounds and the other settings had resolved the jams. Didn't mean to aggravate you. Good luck with it.

Re: Getting jams caused by what I think may be heat creep

Remove the door that holds the idler pulley and check that one end of the pulley shaft hasn't started to come loose (you shouldn't be able to wiggle it). The shaft is only 1mm longer than the pulley, leaving very little metal to grip the printed part.

After 200 hours of flawless prints, my printer had the symptoms noted in this thread, which became increasingly severe until I couldn't successfully print anything. I had the entire hotend apart before I noticed that the idler pulley was the problem. I replaced the shaft with a 3 X 22mm part and the printer is working perfectly again.

If you received your MK3 as a kit you can easily make a 22mm shaft by cutting the head and threaded portion off of one of the long screws in the extras bag.

Re: Getting jams caused by what I think may be heat creep

Just re-read this thread, and didn't see mention of layer issues. Thought you were having concerns about temps and sounds and the other settings had resolved the jams. Didn't mean to aggravate you. Good luck with it.

You're not aggravating me. This printer on the other hand though... I'm going to revert to v3.3.1 firmware tonight and make a few tweaks and see about doing some more test prints. Test prints is of course what we buy our printers for... right?!

Re: Getting jams caused by what I think may be heat creep

Remove the door that holds the idler pulley and check that one end of the pulley shaft hasn't started to come loose (you shouldn't be able to wiggle it). The shaft is only 1mm longer than the pulley, leaving very little metal to grip the printed part.

After 200 hours of flawless prints, my printer had the symptoms noted in this thread, which became increasingly severe until I couldn't successfully print anything. I had the entire hotend apart before I noticed that the idler pulley was the problem. I replaced the shaft with a 3 X 22mm part and the printer is working perfectly again.

If you received your MK3 as a kit you can easily make a 22mm shaft by cutting the head and threaded portion off of one of the long screws in the extras bag.

Thanks for the suggestion. I have already checked and rechecked this. Before and after upgrading to the R3 / B7 parts.

Think my test for tonight is going to be to tighten the idler screws past where Prusa recommends and see if that helps any. Maybe event print 5 degrees hotter than I have been too.

Re: Getting jams caused by what I think may be heat creep

Hi! I do have quite the same problem and I did try to tighten the idler screws, no luck there. It does seem that lots of retractions and lots of small infills in a layer have a major contribution in the problem.

Re: Getting jams caused by what I think may be heat creep

Were there any updates for this? I just started having the same issues with Clear PLA from Fillamentum.

I've replaced the PTFE tube, checked the gears, tried slower, faster, hotter, cooler and the jam only happens after a lot of retractions then I have to unload, snip and reload and it prints fine for a bit.

Re: Getting jams caused by what I think may be heat creep

i experienced my first filament feed issue this morning. 5 hours to go on a 27 hour print. checked the print last night before bed everything was A-OK and when i woke up this morning it was going thru the motions but no filaament was extruding. so I paused the print went to remove and replace the filament ...and well it wount budge. So what has me confused is i cannot remove the filiment from the extruder?? the hot end is hot to the touch and i ran the remove filament setting but it wont budge. was hopeing to get some feed back before i start removing parts?

Re: Getting jams caused by what I think may be heat creep

was hopeing to get some feed back before i start removing parts?

Sometimes removing parts is the only way to fix a bad jam, which it sounds like you have. You might see if other people have better suggestions but imo it sounds like you need to pull the hot end apart.

RE: Getting jams caused by what I think may be heat creep

Posted by: trevor.w9

i experienced my first filament feed issue this morning. 5 hours to go on a 27 hour print. checked the print last night before bed everything was A-OK and when i woke up this morning it was going thru the motions but no filaament was extruding. so I paused the print went to remove and replace the filament ...and well it wount budge. So what has me confused is i cannot remove the filiment from the extruder?? the hot end is hot to the touch and i ran the remove filament setting but it wont budge. was hopeing to get some feed back before i start removing parts?

If you're game for a last-ditch effort before disassembly:

• Raise Z to max.
• Open the extruder door.
• Inspect the PTFE tubing protruding below the Bondtech idler gear. Any chance you see any filament protruding that you can grab with tweezers?
• Heat the nozzle to 285C.
• Insert (ideally) a 6in/15cm 1.5mm rod from above down through the filament feed, past the open Bondtech gears and into the PTFE tubing. (A 1.5mm hex wrench can be used in a pinch but it probably too short to help much.)
• Brace the extruder assembly to avoid twisting and apply some downward pressure on the probe. Can you get it to push the blockage into the hotend to extrude?
• Remove the nozzle (following E3D guidelines) and use pliers to hold the rod as you push it up through the hotend from below.
• Press upwards firmly avoiding twisting the extruder assembly. Let the rod heat up (thus the pliers) and melt the blockage. Can you push it up to where you can grab it out of the PTFE tubing?

With any luck you can get the blockage to pop out without any disassembly. Here are some pics of the procedure.