My build started all the way back in late 2016, when I quickly built mpcnc, did a couple of simple jobs, but since I was building in my apartment - it was too loud and too dirty to play with, so mpcnc went to the shed and stayed there for long years waiting for me to find time. Now that we are sheltering there - I finally had time to play with it. Did a few cuts, decided to fix a couple defects on printed parts, so just printed burly, rebuilding the whole thing, and today did the first cut on it.
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Now for questions part.
After doing a couple circles somewhat successfully, I’ve decided to go for a harder job - an owl-puzzle thingy. I did a few tries, finding various errors in my CAM setup and other things, but finally got to something resembling a result.
it’s done out of 6mm mdf, 1 flute 1/8" upcut mill, 600mm/sec feed rate, 1mm doc, 8k rpm with 0.3mm finishing pass.
I have two questions:
- although it has assembled, but with hammer =) I’ve set ‘stock to leave’ in fusion to -0.2mm - so there should be 0.4mm tolerance between parts…
- ‘hairy’ edge of cutting… wrong rpm? wrong type of bit?
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And as a separate question (because of limitation of 1image per post for new users):
- on some pieces there’s a strange artifact. What could be the reason?
Not so sure about #1, but #2 is the upcut mill. The only ways to avoid that is to either use a downcut bit (although that make chip evacuation more difficult), put down a thin sheet of backer material to try to prevent the tear-out, or suck it up and break out the sandpaper (might also help with #1).
MDF is also notorious for fuzzy edges.
Another alternative for the fuzzy edges is to cut it “good” side down. You’d need to flip the CAD and regenerate the CAM if it wasn’t symmetrical.
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This, too…
Have you squared your machine? You can search for ‘squaring’ (Square X/Y granty problem - #19 by jeffeb3) or ‘calibrating’.
Also, draw a crown (EstlCAM Setup - V1 Engineering Documentation), as that can reveal a lot to some of the real gurus around here. Rasputin had nothing on some of these guys… 
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