I know Lulzbot uses Village Plastic ABS for the extruder_body_hex_v1.4.1.stl. Has anyone made this part in PETG? I have PETG but don’t have any ABS on hand. Anyone have any experience or envision any issues I’d have with the part in PETG? TIA
Glass transition temp for PETG G is around 80C degrees I think. So it would get soft below that temp. ABS glass transition temperature is 100C. You’d probably be find to use it for the front and back bed bearing mounts or the X axis print head bearing mounts, but I might ponder using it if you’re making anything that is holding the print nozzle. I would think most things would be fine.
Another thing to consider is the motor gets pretty hot in use and might soften the PETG, so ABS might be better for the extruder body.
Thanks for the feedback. Good points. Printed one to test. Used the extrusion width/layer height/wall thickness/infill settings from the Lulzbot G Code with the temps and speeds for PETG. The part printed Ok, but the bores for the bearings are both about 0.5 mm larger than the bearing OD. Needless to say, the bearings are very loose in the bores. I checked the bore diameters in the model and the bearing bore is 22.5mm. The bearing OD measures 22 mm. Is the 0.5 mm clearance for ABS shrinkage?
Yes. Also, do not use that specific bearing. You 100% need to use a sealed bearing at that location, otherwise the plastic shavings will get in the bearing and lock it up. Best case scenario it freezes and destroys your hobbed bolt over time. 608zz bearings aren’t very expensive, so well worth the time and money. Or 6082rs. As for the clearance issue, you could wrap the outer edge of the bearing in tape and make a friction fit that way.
Good eyes Piercet! No this is just a bearing I had on hand. I will use the bearings from old extruder body or replace if necessary.
Do you know of any source for shrinkage data for 3d print filament? The manufacturers don’t seem to provide detailed specifications.
It varies based on the styrene content of ABS. On average it’s around 8%. Many ABS profiles have that built into their parameters already though so it can be difficult to tune. Villiage plastics and push plastics both shrink about 8%. PLA tends to shrink far less, maybe 1-2%
Thanks Piercet. Shrink rate for PETG must be next to nothing. Will test shrinkage once I get the ABS.
I didn’t really want to go down the road of trying to print in ABS, but I’ve had spectacular luck making extruder parts from nGen, and haven’t had any issues with its lack of shrinkage. In fact my fully self-printed nGen extruder with a .3 nozzle seems to print just as good if not better than my stock abs one.
I hope you meant 0.8% shrinkage??