Printing extruder parts with ABS or PETG?  

Re: Printing extruder parts with ABS or PETG?

So has there been any consensus on PETG vs ABS for the replacement parts yet? I'm in the same spot, ready to print some extras, but I don't want to print in ABS if the parts will shrink from the originals. On the other hand, I don't want to print in PETG if the original models already have ABS shrinkage taken into consideration... Maybe that's the better question. Does anyone know if the parts STL package from Prusa is 100% sized with the final result?

Thanks!
Brian

Re: Printing extruder parts with ABS or PETG?

I printed with PETG and the sizes matched perfectly with the parts that came with the kit so I'd say that ABS shrinkage was not taken into consideration.

Re: Printing extruder parts with ABS or PETG?

I printed with PETG and the sizes matched perfectly with the parts that came with the kit so I'd say that ABS shrinkage was not taken into consideration.

Excellent! Thanks for the quick reply with your experience. I'll queue up the parts while I have my PETG loaded then.

Re: Printing extruder parts with ABS or PETG?

The pictures I posted were printed from the STL files without any scaling. So I assume you need some scaling up if printing with ABS.

Re: Printing extruder parts with ABS or PETG?

The pictures I posted were printed from the STL files without any scaling. So I assume you need some scaling up if printing with ABS.

Out of curiosity since I never printed with ABS, how bad is the shrinkage with ABS? Is the shrinkage consistent so that once it is determined all prints can be scaled to the same percentage? How will one determine this percentage? I assume this needs to be determined for each different manufacturer? Curious minds want to know. 😀

Re: Printing extruder parts with ABS or PETG?

Out of curiosity since I never printed with ABS, how bad is the shrinkage with ABS? Is the shrinkage consistent so that once it is determined all prints can be scaled to the same percentage? How will one determine this percentage? I assume this needs to be determined for each different manufacturer? Curious minds want to know. 😀

Easier to just avoid ABS. 😛

Re: Printing extruder parts with ABS or PETG?

I've just printed a spare X end (the idler end) due to a few cracks appearing. Printed in ABS using the github STL files. I scaled it to 101% in slic3r, assuming that would be a good first attempt at allowing for shrinkage. But, weirdly, the part is just over 1% too large in all dimensions.

Would seem strange if the STLs were pre-scaled to allow for shrinkage. Either that, or I have special magical non-shrinking ABS (the way it self-removed from the bed on cooling tells me this probably isn't the case though)

I might do another test producing the STL myself from the SCAD files, will report back here with my findings

EDIT. Went to double double check my measurements. Seems like X and Y aren't too bad actually, but my object is definitely way over in Z (which is more likely to be off, nature of the beast). So I think if I go for something nearer 0.5% it'll be as close as one can expect to get. Rigid ink ABS btw, in case anyone wants to know.

Re: Printing extruder parts with ABS or PETG?

💡 @andrew: why don't you scale only in x and y direction ? slic3r allows scaling at each dimensions seperately.

❓ by the way: were you able to open the scad files in openscad (or another program) ? here i had severe issues with openscad. simply couldn't manage to export the scad file in another format (not even stl).

Re: Printing extruder parts with ABS or PETG?

Was just thinking about that option. Given that we print in layers, I suppose it isn't ridiculous to expect ABS to behave differently between XY and Z (in how it cools/shrinks).

Most of the SCAD files i've tried from github have been ok. I noticed that with the X end that (unless I'm not seeing it), that the X end idler block and Z bearing holder are in separate files (presumably because the bearing part is shared between both ends of the X axis). I haven't tried exporting the prusa SCAD files into STL yet though, maybe that's where it goes badly.

I'll probably do some testing and report back if I come to any solid conclusions on another thread (rather than hijacking this one).

Re: Printing extruder parts with ABS or PETG?

I printed an extruder body in Prusa orange ABS and the dimensions are more or less the same as the original part.
I installed the part it works(except for some sagging on bridges and a corner warp).

I don't think they adjusted for ABS shrinkage. I contacted support and they said all the parts are printed in PLA (except for the rambo housing which is PETG) at default settings in Slic3r.

I measured with a caliper and the difference between the parts is well below 1%.

Re: Printing extruder parts with ABS or PETG?

Prusa support said all the parts are in PLA except 2 in PETG? I don't think so, it's ABS. But probably the goal was to say that most parts can be printed in PLA. However, I suspect PLA to not be flexible as ABS. In case of continous stress, I would avoid PLA, and especially for hot parts!

I have ordered BioFila PLATec, just waiting for the delivery. Considering the small technical data I found, it will be only better for temperature, not for mechanical stress.. But it's easier and more precise than ABS, I suppose 🙂