I have been recently redesigning handles for Bodum-like glasses for a friend. The first couple handles came out great. Some other designs with shallow curves along the grip have been producing some blotchy surface defects, as if that portion melted. Please see photos. This defect usually appears around a height range of 3-10mm from the build plate, mostly along the edges of the grip. I was hoping to get some assistance from the community on how to remove these defects and improve the surface quality. Below I show my printer settings and some tests I did.
Bambu Lab A1 printer – 01.07.02.00 (not latest)
- Printer has around 800 print hours.
- Printer was recently lubricated and cleaned. I did tighten the belts and springs at least once, but that was some time ago.
- I’m using the Textured build plate since some prints have a design on it that looks better when textured.
- I use the Bambu Lab A1 0.4mm stainless steel nozzle.
- Filament is fed through the AMS Lite - 00.00.08.15
Bambu Studio – 2.5.0.66 (not latest)
- Most prints will be done with Bambu PLA Black. I do have a filament dryer and have recently dried it. I also just opened a fresh roll and did at least one test print with it.
- Most test prints had a bed and nozzle temperature of 65C and 220C, respectively.
- I did not change the filament settings for PLA except for a few retraction settings. I modified these settings to increase the z-hop distance since my nozzle begins to touch the part near the top of the handle when it is printing the clamp portion. I sometimes lower it for shorter parts.
- Some other settings I changed from default are print infill first, avoid crossing walls (including supports), bottom shell thickness is 1mm, sparse infill density of 50% (I need it to be pretty solid), and a handful of speed settings (see photos).
I did some testing by printing just the grip portion of the handle with different settings but that has not produced any significant improvements. Here are some things I did:
- Changed heatbed temperature from 65C to 60C and then 55C. No changes and the 55C test detached from the build plate.
- Replaced curve with an unsupported 30deg incline, in case the large radii curve was the problem, but the defects still occurred.
- Added and removed supports near the base where the tangent angle of the curve is under 25deg. Tried varying the Top Z distance and interface pattern but produced no improvements.
- I have been using the Variable Layer Height setting in which most of the beginning layers were between 0.08-0.10mm, except for the first layer which was 0.20mm. I attempted a print at a constant 0.20mm height, however the defects still showed up.
A couple things I can’t change if suggested:
- I can’t change the design significantly. The grip must be the dimensions I currently have, but I can modify the fillet radii of the edges a little, currently at 1mm.
- I can not change the orientation of the print due to the clamp portion of the handle needing to be positioned vertically.
I read a few forums/articles and based on what was mentioned, it doesn’t look like the nozzle is grazing the part or staying too long near those portions. It was also mentioned that the heat from the heatbed or nozzle may cause the part to take longer to cool and is still malleable by the time the next layer is placed on top of it. If it turns out it needs more time to cool, what speed or delay settings would you suggest I modify?
Feel free to ask me follow-up questions and thank you for reading.