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  • Q: Having an Issue with Plywood Chip-out

    I am trying to make a box out of 1/2 inch plywood using box joint/finger joint joinery.  I have a box joint jig made from same plan as this one: http://www.youtube.com/watch?v=lmrGa_LDxoE.

    The plan calls for a sacrificial hardboard plate directly behind the work piece and supported/attached to the jig itself.  You can see it in the video as the dark piece in the center of the face/fence part of jig.  Its purpose is to sit directly behind work piece and help prevent chip-out, but it does not seem to be working as intended for me.  So I am wondering if issue is arising from my dado set, which I think is still pretty sharp, or the fact I am using plywood (although if I use a second support/sacrificial board, the chip-out is significantly reduced to near zero).  Or is there something else I am doing or not doing that could be causing this?

    Any thoughts or observations would be appreciated...



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