20 MM hole is 19.2 MM

Okay, so I am trying to make a spoilboard with 20mm holes to hold a Festool dog.

But the holes are coming out undersized.

Using Easle, which is I know is hack, but I’m just starting.

I’m “clearing out a pocket” on a 20 MM hole. The dog is something like 19.6. (I am using calipers)

Any ideas what might be going on?

I’m using 3/4 MDF and a slow feed rate.


Check your bit diameter…

What software are you using.
I did the same thing, then realized In fusion 360 had set it to leave .02 inch which made it to tight.

This is one of those times where you might want to dial-in the hole size on a smaller scrap piece first, before you actually cut the spoil board. Try taking 1 or 2 finish passes thru the hole to see if it will come in closer to size, then tweak the hole size in Easel until you find the sweet spot.


I’m not familiar with Easle specifically but the g code generated by some programs is going to be a bunch of straight line segments that resemble a circle when done but might be imprecise when measured. Circular or arc moves would be identified in the g-code as a G2 or G3 command where as straight lines would be G1 commands.

I second Bill’s suggestion of measuring the actual bit size, I ended up with a 6mm endmill in my inventory instead of a 6.35mm one.

It may just be a case where the gumminess of the material isn’t cutting cleanly and you need to oversize the hole in your design slightly or use some sanding to remove the uncut fuzz. I use steel dowel pins in my wasteboard setup that are .500 and I had to machine the holes in the wasteboard at .508 for a decent fit that didn’t require a slide hammer to remove the dowels from the wasteboard. When I cut corresponding holes in my workpiece (usually hardwood) a .502 hole works best.