Hatchbox TPU Jamming / Not Feeding

[MASTER_E]

Hello everyone!

This is my first post. I've been lurking in the shadows a while reading up on my new M2 revE. ( I LOVE THIS MACHINE! )

Which brings me to my issue. I've been trying to print some Hatchbox TPU and it keeps failing.

So I've pulled some slack through the feed tube and tried nursing it through the extruder but once it stops extruding the only option is to pull it and start it again. I experimented with extruding at 220F and extruder tension but that didn't help and I haven't figured out what is happening yet.

I thought maybe its getting jammed up below the gear in the extruder but haven't taken things apart yet to confirm.

Does anyone have some TPU printing success and advice for me?

My printer is all stock and I've been running the PLA settings.

Thank you!

Eric

[Phil]

I am not sure about Hatchbox TPU; there is information about other flexibles in other threads.
I find a larger nozzle helps, 0.50mm, and I print roughly 50% the speed of ABS,PLA, etc. Your temperature also seems low. Other flexibles I use require 250C or so.
I had trouble printing softer filaments with a 0.25mm nozzle. The extruder gear would keep pushing, while the filament was bound a little further down, resulting in overlap of the filament. You need to disassemble your extruder to check this.

[MASTER_E]

Thanks for the recommendations. I’ve tried extruding at various temperatures all the way up to 250C with little success. Through all my attempts I’ve started to notice a trend. It’ll feed for a little while then all of the sudden it will stop and slowly purge what’s left and continue ghost printing. The gear is turning but nothing is being extruded.

I was never able to get the extruder apart and actually see what was going on. One of my failed prints and a very very jammed up filament drive. I had to work on it stepping forward and backward while wiggling/pulling the filament and it eventually came out. It was very kinked up and folded. I wish I had taken it apart to see where it jammed exactly.

I’m also noticing that this filament is not round, its flat in places. Overall, I’m not very happy with this filament. A friend from work just bought a roll of NinjaFlex. I’m going to get a look at that and take a sample home to see how it compares. The only way I could see getting this hatchbox tpu to print is by modifying my filament drive to tighten up some tolerances and extend some guides all the way to the gear so the the filament cant squirt off to the sides.

[ednisley]

its flat in places

Sounds like a good reason to return that box o' filament: it's certainly not inside any reasonable diameter tolerance. [mutter]

If the filament isn't freeway-flapjack flat, adding a spring to the clamp screw on the drive might help:
https://softsolder.com/2016/10/11/maker ... feed-gear/



The general idea is adding a little compliance to the lever arm, so it can continue to press with (about) the same force regardless of small diameter variations. It certainly can't cope with a dead-flat section, but it's a start.

Also, if the flats came from mashing the filament, then those sections might be more than 1.75 mm wide and can jam in the filament drive holes. You can ream the holes with a 2mm drill (that's #47 or 5/64 inch, for we metric-challenged Yanks) to ensure proper clearance, because sometimes they come out a bit narrow.

Somebody around here inserted 2 mm ID brass guide tubes into the drive block, extended them with minimal clearance to the drive gear, and seemed happy with the result.

[Phil]

Ed,
What's with the chewing gum?

[ednisley]

It's actually brown hot-melt glue kinda-sorta anchoring a snippet of blue oxygen tubing as a socket for the end of the filament guide tube.

I keep meaning to print one of those fancy drives with a built-in socket, but … [sigh]