Kerf Offset in Cut Settings Editor is rounding corners off and not showing kerf offset in preview

As per the title, when I apply an inward or outward kerf offset my test piece ends up with rounded corners on the outside or inside corners, pics below. Please help.

Zero Offset

0.15mm Outward Offset

-0.15mm Inward Offset

Settings for -0.15mm Inward Offset

That’s basically how a kerf works. Think of a router bit running along the original shape. It produces a nice curve at sharp corners on both the inside and outside edges of the cut.

Make a copy of the original shape on a tool layer and you’ll find the curve is exactly centered on the sharp corner with a radius equal to the kerf offset.

You may want to apply the Offset tool to the original shape:

Think of it as a DIY kerf control.

Ah, right, well then!.. Thank you. I use the measure tool a lot, is there a way to preview the design with the kerf adjustment and have visual confirmation of the intended output? I can print all three out as test pieces and get the calliper on them, I just like to see numbers on the screen!


The usual Preview window will do that, although you don’t get any measurement tools:

If you put the original shape and the kerfed shapes on separate layers, then you can measure between them without doing a Preview. Forgetting to disable / delete the layers you don’t want would produce confetti on the platform, though.

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All the kerf adjustment does is offset the tool path one way or the other a set distance.

It doesn’t round corners in my experience and if it rounded one, it should round them both…

Is this a closed path and how large is the kerf?


Kerf is 0.15mm and yes closed path

A quick test …

The basic shape is a 20 mm square:

With an absurdly large +5 mm (outward) kerf:

With a similarly large -5 mm (inward) kerf:

Overlaid as separate paths with offsets:

The outward kerf gets rounded corners because that’s how the path can stay 5 mm away from the point at the original sharp corners.

I was wrong about the inner kerf: it stays square, because that path is constrained by both sides at the corners. I was visualizing the rounded interior corners left by a cutting tool offset inward from the perimeter, not what you get by tracing that perimeter with the tool center: you can’t make a square hole, but you can make a square post.

Memo to self: always run the test!

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