Extruder in PC-MAX experience
Hello,
I've upgraded my extruder on my MK2.5 some time ago and used PC-MAX instead of PETG. This works pretty well and had no issues so far. Now I did the same thing on my MK3s+MMU2s. Here are the results:
It looks that there are a lot of moving forces around the MMU2s extruder parts. At first extruder idler broke at the tension screw. I reprinted it much stronger in PC-MAX hoping it would work. Couple days later a MMU print failed because of the IR sensor not triggering. Close inspection revealed pretty big damage:
- Extruder idler lever broke off
- Around the tension screw I saw a crack but it did hold
- IR sensor holder got loose destroying extruder body and adapter printer
I reprinted all three parts with PETG and replaced those. It's pretty easy in R4. Printing fine again ...
Result: For MMU2 printing at least the three mentioned parts need to be printed with a material which can handle to be bend all the time.
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
RE: Extruder in PC-MAX experience
I never tried PC-Max but i have an unopened spool at home and i was thinking of giving a try. Basically i wanted to print the fan shroud and extruder cover since they take the most heat. I Print with CPE HG100 and the small thin edges of the bottom part of my extruded cover soften and broke. It didn't affect the printing quality but i decided to improve the heat resistance with PC-Max. I'm glad that i found your post since at some point i was considering replacing the whole extruder but it seems that PC-Max has also its limitations compared to PETG. Did you use 20% infill as recommended by prusa? I was thinking of going up to 70-80%.
RE: Extruder in PC-MAX experience
I'm not surprised, PC can be quite brittle and tends to fracture under stress. You might have better luck if you can anneal the parts after printing to relieve the thermal stresses from cooling.
RE: Extruder in PC-MAX experience
"Extruder idler lever broke off" should never happen because the lever should be only moving in free space under zero load
RE: Extruder in PC-MAX experience
@andreas: I went 50% gyroid and 4 walls. The 4 walls are more relevant then the infill percentage. You will not gain any big advantage if you go higher then 50% infill. Fan shroud and extruder cover are still fine in PC, so go for it.
@vintagepc: During the annealing process the part will loose the dimensional accuracy. It's kind of essential for the extruder, so isn't really an option.
@david: Agree. Might be a consequence of part displacement and other damage. The breaking point looked very interesting though.
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram