Spent entirely too long trying to make this for my brother Andrew (after the depicted saint). It was probably my fourth try engraving a 3d sculpture like this but the first, mostly, successful run as well as the first try where I really double checked everything. I’m happy to give it to my brother as a present, I wouldn’t be willing to sell it the way it came out. It’ll probably be redone once I get finished with some other projects. Solid birch wood from a reclaim place. I could use some advice troubleshooting. But first, the story.
hot off the mill
I wanted to try staining the sides and then sand off the tops to highlight but that didn’t go so well. Didn’t try too hard getting the stain off since I knew I wanted to redo it anyways.
Right side Z motor also seems to lower less than 2 mms over 1000’s of Z changes. I checked the grub screws, filed down the lead screw so there’d be a flat spot for the grub screws to nest in, and made sure the Z was level to start but still happened. So that’s why the top right went all of the way through, not too worried about the z drop right now though. Decided to make some hand changes by carving out more with a dremel and adding a backsplash. A happy accident
And the big reason for a wanted redo are the two horizontal cuts near the bottom of the picture. I ran a 1/4" bit for a rough pass, switched to a 1/8" ball mill for the finishing and after cutting most of the bottom frame, the cnc didn’t raise up and went straight though. I stopped it, ran it back to x0,y0 and reset Z and tried the finishing pass again immediately. About 1/2 way through the bottom frame, it dug in again. Went back to x0-,y0 reset Z and then made supper for an hour. Came back and ran the finish pass at 80% speed after that, same g-code and no issues. Only thing I can think of is the Z stepper drivers over-heating (garage was 50°F, no fan cooling on the board). Any other ideas?
Roughing pass 1/4" 10mm/s, 3 mm DOC, 2 mm/s z, 85% stepover (0.5 mm left for finish pass)
finish pass 1/8" ball nose 15 mm/s, 10 mm DOC, 3 mm/s z, 15% stepover