Auto Adjust Router Dado Jig - Glenn Bradley

glenn bradley

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[Originally posted in this thread - VM]

Don made the mistake of asking for more jig posts so here's the next with more to follow. The concept of the jig has different versions. For any version you want some flat stable lumber. I had an old maple table top that was part of my parents newlywed furniture 50-odd years ago. It had picked up some water damage while making it's travels from one of my dad's garages to the other over the years. I ended up with it and it has been waiting for a second life.

The jig requires two guide rails to control the width of the cut and two end rails to support the guide rails.

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The general layout allows the guide rails to open and close for different widths of dados.

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Over to the drill press to drill some starter holes for the adjustment slots.

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On the narrow guide rail I also need a hole for the carrige bolt and a recess for the head of the bolt.

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As my router table was down I used the old standby to cut the slots.

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Cont'd in Part 2
 

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Auto Adjust Router Dado Jig - Part 2

To allow the router bit collar to ride along the guide I cut some rabbets. I make the cut deep enough so that in a later step the collar will ride in the rabbet and the bit will cut the extending shelf of the rabbet to size.

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Here's a shot of trimming the rabbet 'shelf' to create a sort of zero clearance reference edge on the guides. I now know using this guide and bit, the cut will be right on that edge.

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With that done I can attach the side rails permanently to the wide guide rail.

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With the side rails attached I add the carriage bolts, fender washers and some knobs for the narrow guide rail which moves to set the dado width.

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Now using the slots in the side rails and the carriage bolts and knobs, I can size the dado width using the actual material that will occupy the dado.

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Then I make the cut.

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Now even if my material ends up being an odd thickness I can still make a nice tight dado.

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