Can I leave the TPU Feed Assist Module in place when using non-TPU filament types? The “can I” is a misnomer, because I can, but is it recommended and will it cause issues over time to the toolhead, should I reduce the module force, any considerations?
Non-motorized spool holder > PTFE tube > TPU Feed Assist > PTFE tube > Right nozzle (No buffer).
The force/calibration will probably need to be done with the filament you are going to use like you mentioned since I would guess stiffness and the pressure switch on the outlet will need to have that factored to prevent grinding or stalling. Edit to add: If it can go through the buffer I’d still go that route feeding manually, only things that can’t go through the buffer and would need the assistance to keep it from under extruding.
Yes. Some people are using it for PPA-CF and PPS-CF.
Given that fact, it’ll pretty much work for any filament.
It’s basically a Bowden drive extruder, so it should be able to handle whatever you throw at it.
Essentially all the module does is push filament until the resistance is too high, which is quite a lot (150-500grs)… with a soft filament my guess is the PTFE tube would create the majority of resistance and act like a buffer. With a rigid filament the extruder would need to absorb it, so what happens with retractions where you have 2 motors competing?
That’s why I would only use it for soft filaments. There isn’t a reason to feed a rigid through it when you can feed it normally as an external and let the extruder motor do the work.
Maybe I am missing something but I don’t see a reason outside of soft filaments.
They don’t compete. The TPU assist module uses a closed loop control algorithm to keep the extruder “fed” based on force feedback via the PTFE tube attached to it’s outlet.
Two reasons:
PPA-CF and PPS-CF.
A third, for fun:
Printing off of extra large spools. The extruder drive can’t pull from very large external spools unless they are on exceptionally smooth running rollers. The mass moment of inertia is just too great. The TPU assist can be used to pull filament off these big rolls easily, ensuring consistent prints.
Thats something I didnt consider, makes sense.
There’s no data Rx/Tx between the module and anything else, so they sync nothing.
PPS-CF I have not problems with feeding direct through the buffer. PPA-CF I’m feeding through the TPU bypass and with feed assist module. Also using it for 3KG polymaker spools.
You’re right that they don’t transmit and receive an electrical signal from one to the other, but they do transmit and receive a physical signal - as the filament becomes slack or taught between the extruder and the assist module, the PTFE tube acts on a sensor in the module and that signals the module to feed more filament.
It’s a mechanical control signal, but it’s a signal nonetheless.
I’ve cleaned up my previous post, thanks for pointing out it could have been misconstrued!
Better way to visually/audibly experience this is the outlet port has a pressure switch. You can hear it clicking and if you pull the tube out that triggers the filament push. I got that experience early on when trying to get the retract unload muscle memory right. Specifically if using the HF TPU nozzle and no cutter you do it differently.
Ive also started using the TPU module for PET-CF as I had a print failure without it due to too high forces to pull it.