Router Bit Kerf Compensation

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Router Bit Kerf Compensation

Postby hobodog2 » Wed Oct 22, 2014 3:35 pm

How can I compensate for .25" router bit kerf when cutting dogbone shaped or jigsaw puzzle shaped interlocking wood joints so that I do not lose overall diameter of the project?

Just to provide more information; I am making a 16' diameter doughnut shaped circle (with an 8' center hole) using 16 ea pie shaped pieces to make the circle. But I need to have the pieces interlock to hold the circle together tightly, so I want to use a dogbone or jigsaw puzzle joint on each side of the "pie slices" to hold the circle together.

Each of the 16 slices of the circle has 18" faces to mate up with the adjoining slices.

I am thinking that as I cut the individual pieces with the dogbone or puzzle shaped joints, I will lose overall dimension of the whole 16" circle due to the .25" kerf at each joint. I know it won't be much of a loss, but my 16" circle will not be 16' in diameter anymore.

Am I overthinking this issue?

Also, does anyone have a nifty dogbone or jigsaw shaped joint they want to share.

ADDED: Illustration of project
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Re: Router Bit Kerf Compensation

Postby rscrawford » Wed Oct 22, 2014 3:56 pm

You have to separate out each piece, and do a profile cut outside the line. Since most 1/4" bits aren't exactly 1/4", and there is some decompression of the fibres after cutting, you'll probably have to use an allowance offset (something like -.01) in order for the pieces to fit together easier.
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