So I’ve been successfully printing FilaFlex 70A and now even 60A TPU on my X1C as a POC and would now like to start optimizing.
What I did so far was use the Bambu TPA 95A profile as a template, increase retraction to 0.6mm, increase temp to 238C and set volumetric speed to 1.6mm^2 for 70A and 1.2mm^2 for 60A whilst close to fully unscrewing the extruder pressure screw by cutting a hole into the printhead housing’s right hand side.
I’d like to start with optimizing extruder pressure. Could any of you think of a reliable method and measurement that would allow for this?
Secondly. any of you have any other must have settings for (very) soft TPU?
For those of you wondering how I run this: I have a spool holder inside a cupboad on top if the X1C into which I drilled a 9mm hole lined with a short PTFE tube and therefore feeding directly into the extruder/printhead below, minimizing friction the most I could.
I’ve done this mod to mine also.
Here’s a pic someone else posted which will give you all the info you need.
You have to trim both the front and rear covers to make the hole, as the screw is right in between both.
How clean are your prints? I can get 100% clean prints with TPU 95A but going to TPE 83A prints nicely other than blobs on overhangs. I got the impression it’s close to impossible to get perfect prints so I’m pretty curious how good your prints are as I’d love to be able to print it perfectly and the fact you’re talking way softer is really interesting.
Well, there are definite geometric limits to printing with 60A and 70A TPU and steep overhangs are one of the no-gos.
I mainly use those super soft filaments for things like custom gaskets, anti-vibration elements etc. and with such flat geometries the print quality is superb.
Now that I have changed to an aftermarket hotend which allows for the use of CHT nozzles I can wholeheartedly recommend super soft TPU in the X1C when using 0.4, 0.6 and 0.8 CHT brass nozzles. I haven’t yet tried my 0.2 CHT nozzle with those filaments but it should work just as well, even if layer adhesion will obviously suffer.
The max VFR for 60A on a 0.4 nozzle has increased from 2.4mm/s^3 to around 3.8mm/s^3 when using a CHT nozzle, an increase of more than 50%!
Thing is, setting the tension on the extruder gear is still not an established and repeatable method so I’m struggling to find a metric for the sweetspot between preventing clogging and adequate traction for maximum transport speed. As it stands, I have it fully opened all the way when printing with 70A and 60A.
Any advice on a proper test procedure and a metric for the tension relief would be much appreciated.
Unfortunately I’m running aftermarket extruder gear so it might not be the same - but I found backing out the tension until the screw was level with the toolhead cover still gave me enough traction on hard filaments to drive them until the motor skipped, but reduced the pressure enough that I don’t need to over-drive the TPU any more - the flow rate can stay at around 1.00 ±10%
I saw others running 1.30-1.70 on the stock gears and tension settings from the compression of the filament.
I’m pushing 90-92A TPU at 18mm^3/s with that setup.
