Nextruder twists the filament as it feeds?  

RE: Nextruder twists the filament as it feeds?

Thanks, that makes sense. And making the adjustment worked, although it took a few tries. It seems rather precise. I have more tension on the screws that what the assembly instructions suggest (no extruder clicking though!), so maybe that is a contributing factor.

RE: Nextruder twists the filament as it feeds?

For some strange reason mine was printing straight since I assembled it. I did a 7h print today with no twisting. I've changed the filament to a different colour and now it's twisting a lot. Which direction did yours twist and which screw did you adjust to fix it?

Posted by: @jvasileff

Thanks, that makes sense. And making the adjustment worked, although it took a few tries. It seems rather precise. I have more tension on the screws that what the assembly instructions suggest (no extruder clicking though!), so maybe that is a contributing factor.

RE: Nextruder twists the filament as it feeds?

Since you didn't have a problem before changing filament, you might want to make sure the new filament isn't the problem before messing with the tension. But if it is the tension, I'll try to explain the process, hopefully not getting it backwards.

The general idea is to find out which way the filament needs to turn to untwist itself, and then tighten or loosen the appropriate screw to have the extruder twist it more in that same direction. Follow these steps:

1. Unload the filament, but hold the end, not allowing it to un-twist
2. Pull the end of the filament towards your nose, so that it forms a straight line from in front of your face to the spool
3. Loosen your grip on the end and note whether the filament unwinds in a clockwise or counter-clockwise direction
4. If clockwise, the screw further from you needs to be tightened (or the closer screw loosened)
5. If counter-clockwise, the reverse of #4.

To understand steps 4/5, imagine placing the end of the filament back in the extruder, and consider which screw must be tightened to impart the same clockwise or counter-clockwise twist you identified in step 3. The filament will twist in the direction of the tighter screw.

RE: Nextruder twists the filament as it feeds?

Thanks. Now I know I was tightening the wrong screw, hahah! Also I had to tighten quite a bit, so I think the plastic parts were wonky. I already had my idler lever and the hatch replaced with my own prints as the factory ones were uneven and overextruded. But I didn't swap the one that holds the screws. Now I did and nothing twists even with the screws almost level. The idler lever also keeps itself in the middle of the hatch now instead of trying to tilt itself to one side. I guess that's the main reason for the twisting, it must have crooked itself when I was fiddling with filament change.

Posted by: @jvasileff

Since you didn't have a problem before changing filament, you might want to make sure the new filament isn't the problem before messing with the tension. But if it is the tension, I'll try to explain the process, hopefully not getting it backwards.

The general idea is to find out which way the filament needs to turn to untwist itself, and then tighten or loosen the appropriate screw to have the extruder twist it more in that same direction. Follow these steps:

1. Unload the filament, but hold the end, not allowing it to un-twist
2. Pull the end of the filament towards your nose, so that it forms a straight line from in front of your face to the spool
3. Loosen your grip on the end and note whether the filament unwinds in a clockwise or counter-clockwise direction
4. If clockwise, the screw further from you needs to be tightened (or the closer screw loosened)
5. If counter-clockwise, the reverse of #4.

To understand steps 4/5, imagine placing the end of the filament back in the extruder, and consider which screw must be tightened to impart the same clockwise or counter-clockwise twist you identified in step 3. The filament will twist in the direction of the tighter screw.

RE: Nextruder twists the filament as it feeds?

had similar issue my swivels where bend (warped, 2mm gap), but main plate was a **** show, gummy bear stiffness in filament traction area, and overall far from being some what in acceptable quality. Have you tried to untwist filament from my experience its happens only when i mess re-spooling. 

RE:

I put it on a side topic, but I'll put it here as well: I had problems twisting the filament. Tightening and loosening the bolts did not have an effect. Finally, I printed parts idler-lever-A-R2.stl, idler-lever-B-R2.stl, idler-nut-R2.stl and 2x idler-swivel-R2.stl. Print settings: layer 0.15mm QUALITY, infill 20% grid. PETG material. After replacing these new parts, the filament stopped twisting. Do not forget to calibrate the gearbox after assembling new parts!

RE: Nextruder twists the filament as it feeds?

First thanks for all the help.  We started having the twist problem also.  Prusa customer service, while nice was no help. We were told we most likely had a bad spool holder assembly.  They had us reverse the way the eyelet was installed.  We had installed it low.   We noticed that PLA seems to have less twist than the PETG does. Could this be a result of the strength of the material?   Adjusting the screws did not solve our issue.  We ended up reprinting the parts listed above.  At this point we have only printed PLA.  But have not had any issues now that the new parts on installed  I think PRUSA just had a bad batch of prints.

"printed parts idler-lever-A-R2.stl, idler-lever-B-R2.stl, idler-nut-R2.stl and 2x idler-swivel-R2.stl. Print settings: layer 0.15mm QUALITY, infill 20% grid. PETG material.... Do not forget to calibrate the gearbox after assembling new parts!"

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RE: Nextruder twists the filament as it feeds?

I hope you have solved the problem of filament twisting.

RE:

It even helps that the 2x idler-swivel-R2 parts can be glued together on the seating surfaces and only then insert the metal insert and the screw.

RE:

Not sure if this is the answer but I noticed twisting for the first time on my MK4 today. I changed filament from one side of the spool holder to the other side where the extruder was. The curl of the filament was turned 90 degrees to way I normally inserted it. After re-inserting the filament the normal way it wasn’t a problem. Maybe something to check before adjusting tension screws.

RE: Nextruder twists the filament as it feeds?

Have the same issue from time to time.
Although I printed all parts new and tried to get both screws 100% identical the problem persist.

In my case it happens with certain filaments, other do not show this problem. So I could imagine that the roundness of the filament may cause such behaviours when not being exact enough.

RE: Nextruder twists the filament as it feeds?

This position works on my MK4

RE: Nextruder twists the filament as it feeds?

I also had this problem fairly severely with my self assembled kit MK4. In my case the solution was replacing idler-lever-A & B, the idler nut and idler swivel. On removing the old parts I did notice that the set screw seemed a bit loose so maybe that was the cause of the problem rather than the printed parts. However my printed parts are prettier that the one that came with the kit.

RE: Nextruder twists the filament as it feeds?

My kit Mk4 was twisting the spool of PETG that I am currently using, but didn't seem to be twisting the two PLA spools, so perhaps it was a problem with the filament.  ...but because my 11 yr. old did the the vast majority of the kit assembly with me only there for input and support, I never actually had my hands on these parts.  I figured it would be a good idea to take a look while replacing them.  The printer has been excellent otherwise, and as was stated above, the reprinted parts using IS .15 structural are beautiful compared to the  farm printed ones.  The only negative for mine is that I don't have a textured built plate, but they still look much better.

-J

RE: Nextruder twists the filament as it feeds?

UPDATE:  it has been several months now.  We thought the new parts had solved the issue.  Sadly we were mistaken.  We have made a few calls/chats to customer

service.  This is a customer assembly so the warranty is pretty much void. The customer service agents have been so nice, but unable to help. The machine is amazing with PLA. But it just cannot handle PETG.  We have tried different spools and Manufactures of PETG filament.  My opinion, PRUSA fell short here. 

With the numerous posts about the issue, it is a problem that needs to be addressed.  

RE: Nextruder twists the filament as it feeds?

I noticed this happening with my PLA as well... it happens more on some than others. I think I've chalked that up to how much of the spool is gone. The inner coils of a spool are obviously tighter than the outer coils. 

I originally printed all the idler parts listed above with my MK3S+... albeit with what was described on the printables page (0.20mm)...
Maybe I'll reprint them now with 0.15 and STRUCTURAL and see if that helps.

The picture below is from a simple 2 hour print. 
I think one challenge is how the filament is loaded. The nextruder always goes to the far right when done... I've now tried moving it right under the filament feeder to see if that helps with my current 3 hour print.

RE: Nextruder twists the filament as it feeds?

I also found that when placing the spool on the left side of the spool holder, the filament seems to twist less then when placed on the right side? Hence I tend to use the left side more often. 

Maybe something to do with the position of the filament upon insertion during loading....?

RE: Nextruder twists the filament as it feeds?

I haven't yet done a large PETG print to fully test it quite yet, but printing the above parts myself at .15 structural and then very carefully aligning them during installation has eliminated evidence of twisting on small parts for me.  I do have need for a 6-8hr print task for a jig needed at work, so once I have time to model that I'll have a longer print test to try.

With the original parts I was getting early evidence of twisting even on small parts, and I could visually see that the alignment of the idler parts wasn't perfect, either from factory printing or assembly, or possibly both.  The new parts look much better, and assembled in perfect alignment.

-J