Round corners instead of square corners


just finished a project and it went well, except for that the nomad does cut the corners that are straight 90 degrees in my stl as rounded corners.

What can i do to avoid that? NOMAD was set to highest quality, and i used the 101 cutter.
See below the model created by the nomad, and next to it the same stl out of my 3d printer.


Those are corner radii and they are a function of the cutter diameter. In other words, the end mill can only make a corner that it can fit into. You can’t eliminate them completely, only minimize them by using smaller diameter cutters. So in this case you’d want to rough the part out with your 1/8, and then use a smaller cutter, say 1/32 in a finishing pass to approximate the sharp corner.

Thanks Chadw. that makes sense and kind of what I figured, but i was hoping there is a setting that can help that i didn’t know about :smile:

Oliver, a common workaround is to add little kickouts to the corners that are the diameter of the tool. We do this at work a lot when making fixuring that needs to accommodate square-edged parts.

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Thanks that’s a good idea Randy, I will try that!

Those are called dog bone fillets. You can also do t bones. Not sure what software you’re using, but Vcarve pro has easy setting for them.

A couple of minutes work w/ a sharp chisel to square those up.

Oliver, t-bones are just kicked out on one edge (long or short)

rather than diagonally. T-bones are easier to do manually, dogbones stick out less overall, and I think look cooler because they are more CNC-ish. I put little fillets where the big arcs meet the sides too.

Chadw, thank you for the terms. I didn’t know what they were called.

Will, that is heresy! :wink: Seriously, I try to do as little manual work to a CNC workpiece as possible. I’m not very manually adept and usually end up making things worse…

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Thanks, I will try that at my next run :slight_smile: I know what you mean Randy, I tried to manually fix it up with a dremel… Shouldn’t have tried that. Now its not just non-working but also non-working and really messed up looking.

Another alternative would be to alter the orientation of the cutting.

Cut things out in three sections, rotated ninety degrees, including recesses for alignment dowels / pins — that would let one get square sides (but rounded bottoms) — you’d need a flip jig to cut the middle. A bit of fiddling w/ wood varieties would allow one to make it a decorative element.