Router Dado Jig - An Old Friend

[glenn bradley]

I hadn't used this thing (http://www.sawmillcreek.org/showthread.php?t=46406&highlight=Auto+Adjust)in awhile. I was making something out of the 'junk wood' that LOML brings me from work. Not only is it odd-sized but, I didn't want to use my better cutters on this stuff.

I have a trashed spiral bit and this "Auto-Adjust" jig from days gone by. Just clamp it on, aligning the fixed edge with your desired dado location:

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Put a piece of your odd-sized material in; you don't even care what the thickness really is. Lock down the movable jaw:

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Run the router back and forth:

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Perfect fit on some imperfect material:

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I knew I had that jig stashed in the cut-off bin for something ;).

[Chris Konikowski]

Out of curiosity, why the rabbit cut on jig?

[glenn bradley]

Out of curiosity, why the rabbit cut on jig?

It allows clearance for the collar while maintaining a 'zero clearance' edge against the material that can be positioned right on the line where the dado is wanted.

[Paul Demetropoulos]

Glenn,

I use that jig frequently, perfect fit every time.

Chris,

To explain further (if I might Glenn) Glenn is using a collar on the router which offsets the bit, hence the rabbet. Often you see this jig used with guides on the top that the router base runs against, an undersized straight bit cuting the full dado in two passes, as Glenn's can as well. A flush trim pattern bit can be used as well, also with no rabbet. Maybe you knew that Chris, but then for others who may not.

[Vince Shriver]

From Wood Magazine:


Cut dadoes to the desired width with the help of this handy shop aid.

Exact-Width Dado Jig
Here's a jig for routing bookcase or cabinet-side dadoes that exactly match the thickness of your shelf stock. Better yet, no special bits are needed. Just use an ordinary straight bit and a guide bushing. (We used a 1" guide bushing and a 1/2" straight bit.) To start, cut a 3/8" rabbet 3/8" deep along the inside edge of both guide rails (A). Then complete the jig as shown in the drawing below. To customize the rails for a different bushing and bit, install them in your router, and trim the protruding lip of the rabbet in the guide rails, as shown in the Dadoing Detail. The remaining lip will now match your bushing/bit combo.



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To adjust the jig for the exact width of your shelf stock, slip the jig over the shelf stock as shown in the Adjusting the Jig drawing. Pull the guide rails (A) tightly against the stock, and tighten the wing nuts. Slip the jig off the stock, and clamp the jig onto the piece being dadoed, centering the opening between the rails (A) over the marked dado on the side panel. Adjust the depth of cut with your router sitting on top of the rails. Start the router and make one pass with the guide bushing riding against one of the rabbeted rails. Make a second pass riding the bushing against the opposite rabbeted rail.



http://images.meredith.com/wood/images/a_343_1_3.gif

If you like this project, please check out the hundreds of shop-proven paper and downloadable woodworking project plans in the WOOD Store.
WOOD Store (http://store.woodstore.net/)

[Joe Scharle]

I've made a few of these from Shopnotes #76. This plan adds a built-in clamp. Uses the router's base instead of a bushing for dados, although I use a 3/4" bushing for sliding dovetails. Just like Glenn's, I can cut a bunch of dados with a router faster than I can setup the dado stack. Well worth the time to make one of these designs.

http://www.ncwoodworker.net/pp/data/194/Dado_Jig.JPG

[glenn bradley]

I like that built in clamp idea. That is a very cool variation. I'm gonna have to see if I have that issue, thanks.

[Bill Huber]

That is one of the jigs on my list to make, I have watched many people use them and it looks so easy to cut dados.

I have one of those long clamps but setting it up and making sure it is square takes a lot longer then your jig. I just may have to make one this weekend, I have to help a friend make a cabinet for his bathroom.

[Jim Summers]

Very nice / useful jig. Thanks Glen

[Joe Scharle]

I like that built in clamp idea. That is a very cool variation. I'm gonna have to see if I have that issue, thanks.

If you're going to make the jig, here's a couple of thoughts:

1. Use a router with a round base so you won't have to rotate the router, cord & vac hose for the trip back. I make my own so I know they're centered, but I recently tried a Milescraft base and it worked well.

2. Instead of gluing the hardboard guides to the fence, use screws so you can change the hardboard if it gets dinged up.

3. Set the clamp for minimum clearance over the threaded rod. Too much action and the jig will rack off the line.

If you have any problems, just holler.
Joe

[glenn bradley]

Thanks Joe!