TL;DR
Lessons learned - if your SM2 isn’t delivering the results others get, it pays to look deeper and do a thorough calibration. If the SM2 has previously worked OK, repeated print failures mean that something is either broken, out of calibration, or your workflow or materials are faulty. Focus on isolating the problem.
I recently tried to print some models using PETG for the first time. I’ve previously successfully used PLA and even ABS, and I have a pretty good understanding of workflows and processes to succeed with the SM2.
My problems included:
- first layer adhesion (or lack thereof)
- blobs forming on the nozzle
- supports getting knocked over (see blobs)
I scoured the internet for tips and tricks to succeed with PETG, and couldn’t believe the number of people talking about PETG adhering too well to the print surface on SM2!
Chasing and testing individual tweaks wasted a whole lot of time (and filament). Here’s how I plan to approach this type of problem next time.
Major print failure (adhesion failure, catastrophic blobs on nozzle, etc):
- Check slicer settings. Do all speeds, temps, support parameters etc. suit the filament you’ve chosen?
- Check bed calibration. Heat to temperature and let it settle for a while (15min or more) before running calibration. Calibrate z height as per SM2 instructions.
- Check extruder calibration. Recalibrate if out by more than 1%.
- Look for bubbling while extruding filament (i.e. use load function and look at nozzle). Bubbling indicates filament needs to be dried before use.
- Try printing a simpler model with the same filament to rule out problems with the model / slicing.
If catastrophic failure persists, it’s time to dig deeper:
- Inspect the profile of the extrusions on the first layer (if you produced any first layer). The cross-sectional shape of the extrusions tells you a lot about whether you have a problem with over- or under-extrusion.
- Remove and replace the hot end. If you haven’t already realised this, the hot end is a consumable part that wears out over time, and sustains damage when you use high temp filaments (i.e. the PTFE tubing melts). Wear, damage, and obstruction will all undermine your printing success, especially with less forgiving filament types.
- Recalibrate bed, z height and extruder after messing with the hot end.
If catastrophic failure still persists, it’s probably time to ask SnapMaker for tech support.
Partial Failures
If part of the print is failing - e.g. a single section fails to adhere, or you get a tangle of loose filament over a specific feature - the problem lies in the slicer configuration and/or model design.
- For stringing, sagging, tangles: Print a temperature calibration tower to dial in the ideal temp to overcome the failures, and update slicer config accordingly.
- Adjust supports in the slicer
- For partial adhesion failures: add rafts and supports to stabilise the loose parts.
In my case, I found success using the Prusa SM2 A350 profile and tweaking the config parameters to match the Luban settings for “strong and precise” with PETG. The root cause of my problem was a partial blockage of the hot end, and after replacing the hot end I was able to print with good adhesion and minimal blobbing direct to the SM2 print surface. No tape or glue required.