Fillet largest stepdown

Let’s say you are making a mostly 2D part but you want to add a nice fillet to the top edge. I’m talking about a pretty decent sized fillet, like .25in radius or larger. I’m curious what other people would use for their max stepdown?

Also, would you use a regular endmill or ball endmill? My understanding is a ball endmill leaves smaller scallops for the same sized regular endmill on 3D contours.

I assume you will sand after with 320 grit sandpaper or something on hand. So it’s ok to have some scallops, but you also don’t want to have the machine cutting infintismal depths for no reason if some sandpaper can take care of most of that for you.

Have you looked into point round over bits? That way you can keep all your Toolpaths 2D. It’s much faster and easier than 3D (2.5D) carving a radius.

If you’re hell bent on using a bit you’ve already got. I’d go with a ball nose. The smaller the step over, the longer the runtime will be with very little sanding. With a larger step over the runtime will be shorter but you’ll also have to do more sanding.

Another option would be to buy a small router table with some round over bits. This is good when you have to radius both side of a project.


Thanks for your response.

I do think I should purchase some point roundover bits. To be honest I couldn’t figure out what they were called when trying to google around for them. I was trying to avoid another bit purchase but they really would save me a ton of time.

Funny enough I do have some regular roundover bits with the bearing for a normal router. I’ve thought about creating a DIY router table for it, but really just having one for the Shapeoko would probably be a better use of my time.

I think what I was ultimately getting at here though is how rough is good enough. ie it wouldn’t make sense to have .0001mm step down because .001mm is more than good enough especially if you sand after. I was trying to figure out what that max stepover would be, ie 0.1mm or what. Although I am pretty sure in Fusion I specify a step down and not a stepover because I only do a single stepover per depth on my finishing path.

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