# Adjustable Dado Jig for Plunge Router



## diggerop (Oct 18, 2009)

G'day All,
I'm in the process of making a triangular corner bookshelf. The 7 ft rear spine has 45 degree mitres and once they were cut, it looked as though routing out the 5 dadoes on each mitre face would be a little tricky, so I created an adjustable dado jig.

It's a box structure with 2 open sides that clamps to my workbench. The piece to be routed is inserted through the openings and secured parallel to the benchtop and within working reach of the plunge router's reach through the top of the jig.
There are two boards that comprise the top of the box, one fixed, the other has two pieces of wood attatched at right angles to its ends. These pieces sit snugly against the outside of the box and have adjustment slots routed in them, to accomodate the 4 bolts and wingnuts that lock the slide in position.
I used a 13mm bit with a 20mm guide bearing, which meant I needed to set the opening to my required width of cut, plus the difference between the bit and the bearing, in this case an extra 7mm. Depth was set by lowering the router until the bit just touched the workpiece, then using a piece of wood the same thickness as the pieces that were intended to go into the dado trenches, adjusting the depth stop to the that thickness and start routing.
As each dado is completed, it's simply a matter of loosening the two clamps holding the jig, moving it up to the next mark and start routing again. Once each piece is set up, there is no need to adjust anything.

The dadoes are perfect. I had intended this to be a one-off just for this job, but it worked so well, I think I will refine it a little, maybe to accomodate larger pieces and perhaps with hard faces where the bearing runs and maybe even a gauge for set-up, although I just used my vernier, and it only took a few seconds to adjust and lock.

The current version took about 2 hours to make and will handle timber up to 4 x 9 inches. The dado width is adjustable from 0 to 4 1/2 inches.

I'm going to try to post some pics which will explain it far better than my convoluted ramblings above, but as I haven't reached the ten posts mark, that might not work


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## diggerop (Oct 18, 2009)

Addition to the first post, showing stop block clamped in place for blind trench


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## Bob N (Oct 12, 2004)

Hi Henry,

Very creative jig and well thought out. Appreciate you sharing it with us.


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## diggerop (Oct 18, 2009)

Bob said:


> Hi Henry,
> 
> Very creative jig and well thought out. Appreciate you sharing it with us.


Thanks for the compliment Bob. I guess the sharing is what this place is all about. It's a great forum : )


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