Help Calibrating Prusa Core One for PEBA 85A
Hi all!
I'm looking for some help/advice on calibrating my printer/profile for Siraya Tech's Rebound PEBA 85A ( https://siraya.tech/pages/siraya-tech-rebound-peba-85a-user-guide). This is my first time trying to print flexible filament, so I started by following the OrcaSlicer calibration guide ( https://www.orcaslicer.com/wiki/calibration/calibration_guide.html).
I started with the temperature tower and at first selected 255C; this print had issues with the top layer of each section (see photos in links below).
Next I did the max volumetric speed test, which had no notable issues; I selected 3 mm^3/s (sorry, no pictures of this print).
Here's where it got complicated. Next was the pressure advance test where I struggled to find a good value. I searched for advice on this test for flexible filaments, but struggled to find anything helpful/applicable. I tried the "line pattern" and the "chevron pattern" and both either gave inconclusive results, or too poor quality to make a good judgement.
Basically at this point I decided to just go for the part I wanted to print to see how bad it turns out. It actually wasn't terrible, but as you can see from the photos, far from ideal.
So, I'm hoping to get some advice for how to proceed with tuning my filament profile and/or modifying my print settings or model. Thanks!
Here's additional details to help:
- Your printer model.
- Prusa Core One+ (self assembled base model kit with upgrades)
- Any changes from the original design / modifications.
- I made the following modifications suggested in this post: https://forum.prusa3d.com/forum/prusa-core-one-how-do-i-print-this-printing-help/core-one-and-soft-tpu/
- Eventually I put the dry box above my Core One and directly fed the filament into the extruder w/o the PTFE tubing
- If possible, attach a .3mf file (in a .zip file)
- PEBA_85A_3mf_calibration_files - 3 latest test prints I've printed
- CoordinateSystemFrameTool - part I'm trying to print with PEBA
- if any steps have been done on your part to try and fix the situation.
- Before I first printed with the PEBA, I dried the filament per mfg recommendations with the Sunlu filament dryer / dry box. I dried it for 6-7 hours at 70C. After I struggled with the pressure advance tests, I dried the filament again for 6-8 hours and redid the temperature tower; quality was pretty much the same as the first attempt.
- When I started to run into issues with the pressure advance test, I cleaned the nozzle with the provided needle tool and a wire brush.
- I tried printing at 250C, but saw no noticeable improvement
- photos or videos showing the problem you are having if you need help with it, we have a guide here.
- Temperature Tower: https://photos.app.goo.gl/Ufd7R5W4b2pXdgKN8
- PA Chevron Test: https://photos.app.goo.gl/ViLVPdeRiyBDuD1B8
- Test Print: https://photos.app.goo.gl/3PFEm332e6Ps9BwJA
- Let me know if any of these links don't work.
PEBA in dry box, direct feed to extruder:
RE: Help Calibrating Prusa Core One for PEBA 85A
Calibration is for functional prints. PEBA, especially this soft, is not for functional prints. It's for printer feet, shoes, bouncy balls etc. Personally I would just dry it thoroughly first then pick a temperature and a speed down the middle. So 245° nozzle, 80° bed on a textured plate and print it with a 0.6mm nozzle. For max flow, maybe try 14 mm^3/s (75mm/s speed). Calibrating for extrusion multiplier and pressure advance is a waste of time.
Flexibles are tricky filaments, especially the softer ones. @hyiger is overstating the case a little, there are plenty of functional uses for elastic prints; he is right in hinting that calibration is less useful than with harder polymers. The difficulty is in precisely setting up the machine for very soft filament - once set it's possible to print almost any filament without further tweaking.
It's a while since I printed PEBA, on my Mk3 the idler pressure was really tricky to set. I haven't tried with the XL but I suspect it would be impossible with reverse bowden tubes so feed direct to the head...
....and I don't have a Core One to test but I would expect feeding through the filament tubes to be even harder than with the XL - I would definitely mount the spool above the printer and feed direct to the head, also *any* variation in the filament tension will affect the feed rate including when the printer returns slack to the filament path. One way to manage this with very flexible filament is to hang a small weight on a loop of the filament and to feed filament into the catenary as required; you can either automate this or for shorter prints periodically feed manually 'though that's a chore.
Otherwise print it like extra soft TPU - slow right down and dial up the retraction.
Soft PEBA is far too demanding for your first flexible prints; work up to it by stages, start with a stiffer flexible like 98A TPU which will give you plenty of problems to begin with.
Otherwise print it like extra soft TPU - slow right down and dial up the retraction.
Cheerio,
RE: Help Calibrating Prusa Core One for PEBA 85A
The softest thing I print is eSun TPE-83A. I direct feed because the print head can't pull it through the PTFE tube. I never print it unattended, so I just drape it over the edge of the printer and give the spool a spin every now and then so the head doesn't have to pull on it. Pretty much box temperatures, a generic TPU profile and no special adjustments to the printer at all. I've made no calibration attempts and don't know if they'd really accomplish much. IMO, it's never going to print like a perfect PLA print. My prints are all functional- if they do anything like what they're supposed to, they "functional". 😀
Your chevron test is a bit of a stringy mess. It would be nice to track that down. @hyiger version of the slicer is doing good retraction towers with the Core One, so might be worth few minutes and small amount of filament it takes. Caveat- I haven't tried it with flexible filament.
https://github.com/hyiger/PrusaSlicer
RE: Help Calibrating Prusa Core One for PEBA 85A
Thanks everyone for the suggestions! I have a few things to try now. The calibration was definitely seeming sort of pointless in this case, so I guess I was on the right track going straight to the part I wanted to print.