Thread: Fit to Size Mitre Box Jig

I’ve always struggle with mitre joints on boxes. Without a table saw I use either a mitre box with inconsistent results and or a hand made shooting board, I sort of get there in the end albeit with a fair bit of fine tuning.

I picked up piece of cedar recently and after cutting it width on the home made jigsaw table I was pondering how to mitre. It was way to hot in the shed yesterday so I designed and 3D printed a fit to size mitre box in the comfort of the house aircon.

The mitre slot goes 3mm into the base for a clean cut and is 0.9mm wide, the same as the saw blade teeth. The height is 3mm above the stock and the end wall is for stability of the unclamped section. A single clamp holds the stock in place. Overall dimensions are 120x100x25mm. Stock was a fraction under 15mm. Print time was around 12 hours mostly overnight costing around $3.20.

Sometimes theory and practice don’t always work out, but in this case it did, the mitres were clean and square and on first fit up it all looks pretty good. Along with the full support on both sides I think the soft wood and the action of the Japanese pull saw helped. The saw cut was a little more aggressive than I would like but it is the only one I have that will go the full depth.

So for me it was a success. Whether it is worth making one every time remains to be seen, maybe some packing pieces might work for thinner stock.

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