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I'm making a gate from 2x2 material. I want to build-in a half-lap grid. I came up with a jig to use with my router that involves laying the 2x2 side by side in a box 1 1/2" deep then attaching at 90 degrees, a series of 1 1/2" template pieces with a 1 1/2" space between each template piece. As you can see in the photo, I'm able to get results but not consistently enough for my needs. I would like to do this on the table saw with some sort of jig similar to a finger joint jig but would need to make two cuts per crosscut. An inch and a half dado set would be perfect but not an option. Maybe using such thick material makes a jig impossible. Any input would be appreciated.

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    There's no reason you can't do what you want successfully with a router, in fact I think this should be the preferred method for a couple of reasons. Can you identify the source of your consistency issues? You're ganging them together to cut multiples correct, is the squareness of the fence the issue? Or is it maybe that the workpieces aren't firmly clamped so some or all can shift just a hair during the operation? If you get everything dialled in and tight this should be a dream job for the router, resulting in the cleanest, most consistent half laps of any technique bar using a CNC :-) – Graphus Apr 24 at 10:31
  • Graphus-- I'm thinking you are right and I may need to make heavier templates and generally tighten the jig connection to the material. I really appreciate your comments, Thank you. – LesTraveled Apr 25 at 3:23
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So to start by clarifying the issue...if you have a normal finger-joint jig with a stop block the same size as your dado stack there is no way to reference the first cut on each board. Since the stock is wider than the dado stack you'd need two passes, one for the "leading" edge of the half-lap and one for the "trailing" edge. Once the first dado is made on each board you can make the next dado by aligning the stop block on the two sides of the previous dado.

I think the solution will be to have a second, movable reference block whose width is the difference between your stock width and your dado stack width. You'll then make your first cut with the new block set against the jig's stop and the end of the work piece against the new block. Then your second cut with will be with the end of the work piece against the jig's stop. (Note that for this use of the jig the jig's stop should be the stock width plus the new block's width away from the blade.)

For example, say you've got a 3/4" dado stack and your stock is 1" wide. You'll need a stop block 1/4" wide. Your first cut (with the new block) will be from 1" to 1 3/4" from the end of the work piece, and the second cut (without the new block) will be from 1 1/4" to 2" from the end of the work piece. (I'm not using your exact dimensions because I think this makes it clearer what is happening...)

  • FYI, I've never done this myself, so if I'm missing something here please let me know... – SaSSafraS1232 Apr 23 at 23:30
  • SaSSafraS1232 - I think you may have the answer. I'll have to do a drawing before I can see it clearly. Thank you for your help. – LesTraveled Apr 25 at 3:25
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I did something similar to make book shelves for paper backs.

For a given set, I clamped all the verticals together, then made two passes with a radial arm saw to define each side of the cut. Did the same for the shelves. Took out the wood between with a chisel. Since the baseof each cut was buried in the joint, I didn't care if that was rough. My shelves weren't designed to have shelves flush with risers. I wanted to use 1x4 material (3/4 x 3.5) and a paperback is about 5" wide,so the shelves were proud of the risers by 1.5"

You can define the edges of the cut with a regular saw blade, then make a series of passes with a dado to clean out the middle. Make a few extra pieces during the first stage, so you have test pieces to dado.

  • Hello Sherwood, Thank you for your input. I haven't had time to get a jig together but I will incorporate your suggestions. Thanks again. – LesTraveled May 11 at 17:13

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