# Box Joint Jig



## oldrusty (Mar 31, 2011)

Hi. I am attempting to make simple trivets using 5 1/2" squares of 3/4' maple. My set up is a Triton MOF001 mounted in a Kreg bench top table with an up cut 3/8' solid carbide spiral bit. My jig is an MLCS box joint jig with the bit on the fence side closest to me. The gap between the fence and bit is 3/8'. I am feeding the pieces from right to left, first with grain then turning them over and rotating them 90 degrees to cut across the grain. At arms length my cuts look clean but on closer inspection are quite rough, sides and bottom. The bit is quite noisy but hardwood is new to me. My initial cuts were full 3/8" but even 3/16' cuts, though a bit better, are still rough, particularly the cross grain cuts. Any advice ? Thanks Al


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## Selwyn Senior (Jan 11, 2014)

Hi Al

All the best with your project.

Videos I have watched recomend routering the end grain first as it helps reduce tear out. The other thing is to use a piece of scrap as a backer so the bit finishes cutting the main piece and starts into the scrap again protecting the edge of the project.

I'm also wondering given the size of the piece how you're holding it?


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## jw2170 (Jan 24, 2008)

Hi Al, the cross grain cuts are always the most untidy.

I have seen where two layers of 3/8" were laminated together at 90 degrees to each other. That way both cuts are along the grain , not across.


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## CharleyL (Feb 28, 2009)

How about some pictures? Your description is a bit confusing.

Trying to cut box joints on the long grain sides of your material won't work very well. The pieces between your cuts will break off very easily because the grain of the stock is across them and is a weak point. Box joints are intended to be cut in the ends of boards. Getting smooth cuts requires a sharp bit, clamping or otherwise holding your work so that it cannot move side to side at all while the cut is being made, and the use of a backer board to prevent chip-out should improve your cuts.

Charley


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## harrysin (Jan 15, 2007)

oldrusty said:


> Hi. I am attempting to make simple trivets using 5 1/2" squares of 3/4' maple. My set up is a Triton MOF001 mounted in a Kreg bench top table with an up cut 3/8' solid carbide spiral bit. My jig is an MLCS box joint jig with the bit on the fence side closest to me. The gap between the fence and bit is 3/8'. I am feeding the pieces from right to left, first with grain then turning them over and rotating them 90 degrees to cut across the grain. At arms length my cuts look clean but on closer inspection are quite rough, sides and bottom. The bit is quite noisy but hardwood is new to me. My initial cuts were full 3/8" but even 3/16' cuts, though a bit better, are still rough, particularly the cross grain cuts. Any advice ? Thanks Al


This pdf which was posted by Mike some time ago shows what I consider was most common method of making trivets. I have never used a dovetail bit, just a straight one. Things have advanced since this was published and a far simpler method is to make a sub-base for the hand held plunge router and attach a strip of wood the width of the grooves and spaced as you wish, after the first groove the strip sits into it ready to rout the next on and so on. Once one side is complete flip the wood over and do the same at right angles on the second side.


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## oldrusty (Mar 31, 2011)

I am unable to include a photo at this point in time but I am not actualy using this jig to make box joints. I am using it to cut a series of 3/8" deep grooves, evenly spaced 3/8" apart on one face of the pieces and the same on the other face, but at right angles to the first cuts. It forms a lattice you can see through. There is no end grain involved, just with the grain and across the grain. I just need a way to get smoother cuts. Great article Harry but way more complex than I need. Thanks, Al.


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## CharleyL (Feb 28, 2009)

Oh, that's what you are doing, making a waffle! 

OK, for splintering my suggestion for this is to run your router as fast as possible, move it as slow as possible, and make shallow cuts of increasing depth. If you get any burning, try slowing the router some or try different bits like up-cut or down-cut. Scoring the edges of the path of the router should help too. I think that no matter what you do you are going to have some splintering. Also consider cutting the slots diagonal to the grain. This way both sides of the work will have 90 deg cuts to each other, but at 45 deg to the wood grain. I have never tried to make a waffle, but these ideas would be what I would try.

Instead of using that jig, you might consider mounting a 3/8 X 3/8 strip on a temporary router base with the strip located 3/8" away from the bit. You can then index the router for each slot by putting the strip in the previous slot cut. If trying to make shallow cuts, then the 3/8 wide strip can be reduced to only about 1/8" tall and it will still work as long as the base of the router remains flat against the work.

Let us know what works and how well you did. This is an interesting problem.

Good luck,
Charley


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## Mike (Nov 22, 2004)

Two pieces glued at 90°; rout with the grain on both sides to get this result.


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## oldrusty (Mar 31, 2011)

Hi Mike. I guess I should have, to quote you, " kept it simple " and just asked how to make a SMOOTH 3/8" dado 3/8" deep in a piece of maple.


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## Semipro (Mar 22, 2013)

Fast router speed, slow feed rate, sharp router bit 
About as simple I can come with Al


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## oldrusty (Mar 31, 2011)

Hi John. Will try all of the above. Thanks, Al


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