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Woodwhisperer Exact Width Dado Jig Woes

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Forum topic by groland posted 09-02-2018 10:12 PM 1059 views 0 times favorited 11 replies Add to Favorites Watch
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groland

216 posts in 3831 days


09-02-2018 10:12 PM

Topic tags/keywords: woodwhisperer exact width dado jig woes

I have been building some shop furniture. My current project is to build a stand for my drill press. I want to dado the cabinet sides to take the top, bottom and two drawer pockets all made of 3/4 birch plywood.

I built my jig pretty close to Mark Spagnolo’s on The Wood Whisperer. After I glued on the hardwood edging, I ran the timbers over the jointer to help ensure that the hardwood edging was square to the faces of the plywood and flat. I also planed the long edges with a No. 7 plane to make a tight, flat mating of the two guide edges.

When I glued the jig together, I was extremely careful to make sure that the hardwood edges on the fixed guide rail and cross pieces were dead square taking the test on the hardwood insides of the cross pieces and guide edge on the fixed fence. I am truly certain that the right angle where the cross member clamps to the work and the fixed edge guide are square.

I use a Bessey Revo Body clamp to attach the jig to the workpiece. By gripping the end of the long cross piece opposite the clamp while tightening the clamp, I can neither feel nor see any deflection.

Okay, so I thought I had this licked, but when I cut a test dado, the dado was 1/16 out of square over 12 inches.

I noticed that when I had the fence clamped tightly to the work piece, the unsupported end could be wiggled about 1/16 inch. Any sideways pressure on the jig could push the jig out of square.

In my second experiment today, I used my reference square to pencil a line across the workpiece where the dado was to go. I aligned the jig to that line at the clamp end and clamped on the fence. Then, at the unsupported end, I used a C-clamp and deflected the jig to hit the pencil line and routed the dado. This dado was perfectly square to the edge of the workpiece.

If you have made one of these jigs, how accurate is yours? Can you just clamp it down as Mark does and make consistent dados perfectly square to the edge the jig is clamped to? If you clamp your jig down, does it deflect at all as I am describing?

Thanks for any responses!

George Roland


11 replies so far

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lew

12806 posts in 4174 days


#1 posted 09-02-2018 10:32 PM

I have a similarly designed one. I draw the line completely across the workpiece and clamp the jig to both sides of the workpiece. A little extra work but save a lot of headaches.

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.

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Rich

4555 posts in 1008 days


#2 posted 09-03-2018 01:20 AM

I’m not sure which came first (that is, who copied who) but I built this one and it’s rock solid. I made some mods too for easier clamoing. I’ll try to get a photo.

https://www.woodmagazine.com/woodworking-plans/routing/exact-width-dado-jig

-- Knowledge is not skill. Knowledge plus ten thousand times is skill. -- Shinichi Suzuki

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groland

216 posts in 3831 days


#3 posted 09-03-2018 05:28 PM

Lew,

Given the nature of this jig, and the fact that many other woodworkers here mention the difficulty of getting really precise dados—with a dado blade in a table saw or using a router—clamping at both ends seems prudent.

I am presently working on a fix to bring my current jig into better alignment when clamped by shaving the error out of the fence with a shoulder plane. I’ll see if that works any better. If it does, I won’t have to bend the jig as far before clamping the unsupported end.

Thanks for your reply!


I have a similarly designed one. I draw the line completely across the workpiece and clamp the jig to both sides of the workpiece. A little extra work but save a lot of headaches.

- lew


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groland

216 posts in 3831 days


#4 posted 09-03-2018 05:31 PM

Rich,

In the link you sent (thanks!) I see that the photo shows the jig clamped down at both ends. This is a different clamping technique that Spagnolo uses in his video. Do you clamp at both ends as is ahown in your linked photo?

Thanks for your thoughts,

George


I m not sure which came first (that is, who copied who) but I built this one and it s rock solid. I made some mods too for easier clamoing. I ll try to get a photo.

https://www.woodmagazine.com/woodworking-plans/routing/exact-width-dado-jig

- Rich


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000

2859 posts in 1318 days


#5 posted 09-03-2018 05:38 PM


I made some mods too for easier clamoing. I ll try to get a photo.

- Rich

Yes, please post a picture. I’d like to see how you clamo yours.

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Desert_Woodworker

1833 posts in 1633 days


#6 posted 09-03-2018 08:36 PM

Clamo is an Arizona term that we out here use for clamping :)

I believe that it started in the Tucson region but it is now quickly spreading

-- Desert_Woodworker

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Rich

4555 posts in 1008 days


#7 posted 09-03-2018 08:43 PM


I made some mods too for easier clamoing. I ll try to get a photo.

- Rich

Yes, please post a picture. I d like to see how you clamo yours.

- jbay

Dang. Another typo. I bet that’s why my research for information on your air assist airless spray gun kept returning insurance quotes.

-- Knowledge is not skill. Knowledge plus ten thousand times is skill. -- Shinichi Suzuki

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Rich

4555 posts in 1008 days


#8 posted 09-03-2018 08:46 PM

Clamo is an Arizona term that we out here use for clamping :)

I believe that it started in the Tucson region but it is now quickly spreading

- Desert_Woodworker

Or, it’s a portmanteau for camouflage clamps. You sure don’t want to be using those bright red Besseys out there in a war zone.

-- Knowledge is not skill. Knowledge plus ten thousand times is skill. -- Shinichi Suzuki

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Rich

4555 posts in 1008 days


#9 posted 09-03-2018 09:08 PM

OK, here it is. First photo shows the underside. It’s solidly glued with screws. It will not budge. I also made it from some pecan I had laying around. That’s got to add some stiffness. Also, these big-ass Woodpecker knobs can be tightened so nothing moves.

And here it is clamoed to a board. I added the top flanges so I can use lower-profile C-clamps. Taller clamps get in the way of the router handles. And no, I do not clamp the other end. I can push back and forth on that guide rail and it does not budge one bit.

-- Knowledge is not skill. Knowledge plus ten thousand times is skill. -- Shinichi Suzuki

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000

2859 posts in 1318 days


#10 posted 09-03-2018 09:50 PM

Yep, the top flanges make clamoing much better.

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groland

216 posts in 3831 days


#11 posted 09-04-2018 12:47 AM

Rich,

Thanks for taking the trouble to make these photos and providing the explanation on how they work. Very interesting design!


OK, here it is. First photo shows the underside. It s solidly glued with screws. It will not budge. I also made it from some pecan I had laying around. That s got to add some stiffness. Also, these big-ass Woodpecker knobs can be tightened so nothing moves.

And here it is clamoed to a board. I added the top flanges so I can use lower-profile C-clamps. Taller clamps get in the way of the router handles. And no, I do not clamp the other end. I can push back and forth on that guide rail and it does not budge one bit.

- Rich


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