# Math Equation



## LueyD (Jun 19, 2014)

Hello all,

I have an INCRA IBOX jig that I can't seem to get the fingers to space equally across the board. I have leftover material after the final pass. I am looking for the equation you use to figure out the width of your boards to fit 11 - 3/8" kerfs? INCRA's formula does not work. I am attempting to make a finger joint box. Measurements are 8×10x whatever width needed. Any assistance would be greatly appreciated.

Luey


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## TheFridge (May 1, 2014)

Ever tried measuring the finished cut with a vernier caliper?


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## AandCstyle (Mar 21, 2012)

I agree with TheFridge. If you are off by only 0.001" per finger, that is 0.011" across the 11 fingers which is significant.


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## TheFridge (May 1, 2014)

.005 can make the difference between a tight joint and a loose joint. Vernier or dial calipers are a must have bud.


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