Extruder motor constantly clicking/skipping steps + pulleys getting dirty all the time
Hi all,
I have been able to get my MM prusa working from time to time, got it on the 2nd week after delivery started. (so have it for quite some time already)
However, I have never been using multi material printing a lot, so most of the times I was still printing single color/material. And besided a small reduced print quality never had a lot of issues then.
The problem I'm having since quite some time now however is that the motor is constantly clicking and that the pulleys are grinding a lot of filament and getting dirty all the time.
Because of this I have under extrusions to no extrusion at all after some time. This is when doing single or multi color/material prints. The issue doens't seem to be filament affected, since I have tried ABS, PLA, many different colors and branches. But it happens with all of them.
Sometimes when I switch from motor 1 to 2 or a different one it works for one print. But then the issue reoccurs again. (so doesn't seem to be an extruder problem?)
I have checked the spring distances and tried loosening them a bit more.
I have tried changing print temps which did sometimes solve the issue, but was only of short time. (as suggested in another thread)
I have replaced the PTFE tubing with one bought from prusa as a spare for MMU, but didn't solve the issue.
I have cleaned all pulleys before, did solve the issue for 1 print. But then they got dirty all again. I don't think it's needed to remove all pulleys after each print to properly clean them? I also have bought some metal brushes, to clean the pulleys when they are inserted, but this doesn't really help at all.
I have used cleaning filament and tried cold pulls, but also didn't solve this issue.
Did anyone else here had this issue and found a solution to solve this?
Or does anyone else have a possible theory of what is causing this issue?
Thanks a lot,
Tom
Re: Extruder motor constantly clicking/skipping steps + pulleys getting dirty all the time
The clicking sound means that the stepper is having to exert more force than a specific threshold and it's jumping back a few steps to relieve the pressure. If you were to look at the axis of the motor when it's doing that you'll notice it jumps back.
It's usually an indication that there is a clog somewhere or that your filament is experiencing so much resistance that the motor just gives up.
You should probably remove the multiplexer and see if you can manually feed filament through all holes without too much resistance. might be that the metal tubes aren't lining up or something else. Might also be that the nozzle is actually clogged, but then you wouldn't be able to print from any of the extruders.
The clicking sound is basically a notification that you're going to have underextrusion in your model, it doesn't only happen with multiple extruders.
XL (5T) / MK4 / MK3S+-MMU3 / MK3S / MK2.5S-MMU2S / Mini / SL1S
Re: Extruder motor constantly clicking/skipping steps + pulleys getting dirty all the time
Hi Steve,
Indeed that's exactly what I thought, but strange enough I can't seem to get it solved.
Also forgot to mention that I did swap the metal tubes in the multiplexer as well... I will check the friction one more time, but have already done that in the past after replacing the tubes and it was OK then.
Tom
Re: Extruder motor constantly clicking/skipping steps + pulleys getting dirty all the time
Question from someone new that's waiting for their MK3.
Are the tubes that the filament passes through support filament that may be too large in spots? With all the different brands and quality control if over sized filament can play a part in the stepper motor issue?
Re: Extruder motor constantly clicking/skipping steps + pulleys getting dirty all the time
So what I did notice is that there is indeed friction inside the metal tubes...
But this is because the filament doesn't go in straight because it was rolled up on a filament roll of course, so there is always a small bend in the filament.
If i keep the filament straight with my hands there is no friction. (If i keep the filament straight, and put a tube on it, it will automatically go down if I flip the filament 180°)
Then I noticed that when using the PTFE tubing for filament guidance (without motor) I do still feel some friction, but that's mainly when filament is getting in the tubes, as soon as it's in there is a lot less friction. This also because the filament needs to find its way inside the tube I guess... But could this maybe mean that there is a small gap between the tube and the festo? Or is this just because of the small bend inside the filament, so that it's still trying to get bend in the metal tube, but once it's totally in their the filament is getting more straight?
I also checked with different cutting angles at the filament tip, but having a straight or 45° cut doens't seem to make any difference. Also tried a much sharper cut, but this made it a lot worse (as expected)
Does everybody here have this friction when getting inside the tubes? Or does anyone know how to solve that? I do feel that this may be my issue...
Tom
Re: Extruder motor constantly clicking/skipping steps + pulleys getting dirty all the time
So what I did notice is that there is indeed friction inside the metal tubes...
But this is because the filament doesn't go in straight because it was rolled up on a filament roll of course, so there is always a small bend in the filament.
If i keep the filament straight with my hands there is no friction. (If i keep the filament straight, and put a tube on it, it will automatically go down if I flip the filament 180°)
Then I noticed that when using the PTFE tubing for filament guidance (without motor) I do still feel some friction, but that's mainly when filament is getting in the tubes, as soon as it's in there is a lot less friction. This also because the filament needs to find its way inside the tube I guess... But could this maybe mean that there is a small gap between the tube and the festo? Or is this just because of the small bend inside the filament, so that it's still trying to get bend in the metal tube, but once it's totally in their the filament is getting more straight?
I also checked with different cutting angles at the filament tip, but having a straight or 45° cut doens't seem to make any difference. Also tried a much sharper cut, but this made it a lot worse (as expected)
Does everybody here have this friction when getting inside the tubes? Or does anyone know how to solve that? I do feel that this may be my issue...
@ Dave, don't really get what you mean?
Tom
Re: Extruder motor constantly clicking/skipping steps + pulleys getting dirty all the time
How did you insert the tubes? The correct way is to push filament through, insert the tube so the filament sticks out both ends, then slip the Festo over it and tighten. While you finally tighten it, move the filament a few times to make sure the tube is centered against the Festo and you get minimal resistance. There will still be a tiny lateral movement possible so the tube can self-adjust a bit. I'm afraid it's not a very good design. I had to turn over 2 of 4 tubes to get it done (ideally the direction should not matter), also one of the holes in the printed part had to be cleaned up because some filament blobs pressed the tubes against one side.
Bends in the filament should not matter at all. They should be straightened out after the gears and anyway Bondtechs generate lots of torque (just try getting the extruder to slip while it loads, it's almost impossible - don't hurt yourself 
).
Re: Extruder motor constantly clicking/skipping steps + pulleys getting dirty all the time
Ok, so I did insert all 4 tubes now as you suggested. Also I cleaned the pulleys again and adjusted the springs again to 5mm distance between washer and printed part.
Will do some printing again now and will check what the results show.
However I have to notice that I still have tension when sliding in filament at the tubes.
Tom
Re: Extruder motor constantly clicking/skipping steps + pulleys getting dirty all the time
The filament bendiness offering more resistance is a bit weird, since it's only 1.75mm. It shouldn't have that much of an impact.
Are you using a spool that is nearing the end? If so, perhaps try to get it working decently first with a fresh spool with plenty of filament on.
On my 2.85mm I sometimes have issues with spools at their end, because the radius of the filament is too small and it isn't straightening out enough, but have not had this on 1.75mm yet. Still cannot claim to have tried all filaments out there so you never know 🙂
As for the 5mm left on the screws: in my experience with the MM, the resistance should be so that - with some effort - you should be able to manually push in the filament (when the printer is without power).
So mine are a bit more out than that, it was squashing the filament too much initially.
XL (5T) / MK4 / MK3S+-MMU3 / MK3S / MK2.5S-MMU2S / Mini / SL1S
Re: Extruder motor constantly clicking/skipping steps + pulleys getting dirty all the time
Only tested with around 15 different filaments, but I'm pretty sure it's still really consistent in diameter. Also what I mentioned earlier, when I just slide a tube over some filament and straighten out the filament. Every time I rotate the filament 180° it slides down itself with no issues.
When the tubes are in the splitter, it seems that using the PTFE tubing doesn't help enough with straightening the filament to give it an easier entering for the filament.
Yesterday I did only 1 small test print, which luckily succeeded. However print quality wasn't sublime. Will have to do some more testing, but if anyone else have ideas. Please do post them! 🙂
Tom
Re: Extruder motor constantly clicking/skipping steps + pulleys getting dirty all the time
Only tested with around 15 different filaments, but I'm pretty sure it's still really consistent in diameter. Also what I mentioned earlier, when I just slide a tube over some filament and straighten out the filament. Every time I rotate the filament 180° it slides down itself with no issues.
When the tubes are in the splitter, it seems that using the PTFE tubing doesn't help enough with straightening the filament to give it an easier entering for the filament.
Yesterday I did only 1 small test print, which luckily succeeded. However print quality wasn't sublime. Will have to do some more testing, but if anyone else have ideas. Please do post them! 🙂
Tom
Re: Extruder motor constantly clicking/skipping steps + pulleys getting dirty all the time
Haven't been home till now, so wasn't able to test more. Needed to go abroad for my company a few times..
I however did today a new test print but it did fail after around 2 minutes, instant jam for what I could see. And therefor the extruder was ticking again.
But it does indeed seem to be an extruder jam, however I really don't know why anymore.
I changed out the ptfe tubing with a new one from Prusa and checked that the right side was down/up. But keep in mind that I'm getting extruder jams when only printing in one color/material... (not doing multicolor prints at the moment) So I really don't get why I'm having such a pain with only one color 🙁
Anyone have more ideas?