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Trouble with TPU on new MK3S  

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Lost Lighting
(@lost-lighting)
New Member
Trouble with TPU on new MK3S

Ive started selling enough that recently I purchased a second  MK3S. Ive built it correctly as far as I can tell but for some reason when I put TPU through it, it will stop feeding. After pulling out the filament it looks like it is just slipping on the gears. I shouldnt have to tighten the screw any tighter on the feed gears. The same file and filament works perfect on my old one. Any ideas why the filament might be slipping in the new one?

Posted : 12/09/2022 12:21 am
Diem
 Diem
(@diem)
Illustrious Member

Does it work OK with other filaments?

With all flexibles the trick is to have the extruder idler as loose as possible, it should barely nip the filament.

Cheerio,

Posted : 12/09/2022 12:50 am
Cesar
(@cesar)
Active Member
RE: Trouble with TPU on new MK3S

Agree with Diem. The screw that holds the idler have to barely screw in but enough for the screw to be held with the nut and you should be okay. I was having that same issue and I finally got it to work after 2 months.

Posted : 12/09/2022 3:07 am
Lost Lighting
(@lost-lighting)
New Member
Topic starter answered:
RE: Trouble with TPU on new MK3S

It works fine with other filaments, it just has to do with the floppy nature of flex filaments. It seemed like I had it set at the correct tension then I tried tightening some when I noticed it seemed to be slipping but ill see if I can let it off to the minimum and see what it does although I struggle to understand how a looser grip will make it stop slipping. I just went ahead and started my flex print on my old MK3s and started a petg print on the new one so Ill have to wait another 10 hours to find out if this advise works. Thanks!

Posted : 12/09/2022 7:45 am
Lost Lighting
(@lost-lighting)
New Member
Topic starter answered:
RE: Trouble with TPU on new MK3S

Im just confused why it works fine on the old one, never had a problem with flex on it. But now I have to dial it in on the new one to make it work? I don't understand what is different..

 

Posted : 12/09/2022 7:47 am
fuchsr
(@fuchsr)
Famed Member
RE: Trouble with TPU on new MK3S

I don't understand what is different..

These are not super precision instruments. Some variation in the printed parts that hold the idler, and it can make all the difference.

Posted : 12/09/2022 11:27 am
Diem
 Diem
(@diem)
Illustrious Member

I struggle to understand how a looser grip will make it stop slipping

A stiff filament comes out of the grippers more or less in line with the heatblock channel.

Flexible filaments distort to the shape of the grippers and bend a little differently as each pair of gripping teeth compress and uncompress; so the filament snakes slightly.  It only takes one waggle to miss the heatblock channel and the filament begins to fold itself out of the path and pile up...

Cheerio,

Posted : 12/09/2022 12:56 pm
ssill2
(@ssill2)
Noble Member
RE: Trouble with TPU on new MK3S

I've also found higher temp and lowering the max volumetric speed for the filament helps a lot.

Here's the profile I use with good success.  and it works for all my tpus, not just ninjaflex

 

Posted : 16/09/2022 10:52 pm
ssill2
(@ssill2)
Noble Member
RE: Trouble with TPU on new MK3S

I do print with a hardened steel nozzle on that printer so the higher temp might need to be lowered by 5 deg for brass.

Posted : 16/09/2022 10:53 pm
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