# Exact Width Dado & router template jig



## Everend (Mar 15, 2013)

A few months ago I made a template jig, following this design. 




One issue I had with this design is that my pocket holes didn't exactly line up with my dado so there was a little lip at the end/joint. After building this one I thought it would be a better design to drop the pocket holes, run everything on 90degree corners and put a tenon on the end of each piece that would ride in the t-slot cut for the set bolt.

This weekend I started another project where I need to cut some dados so I started looking at posts and videos for zero clearance dado jig. I've watched this video several times now 



 and then Ron Paulk has a couple of videos touching on his version of this one. In Marc's video he challenges his viewers to design a version with the knobs on top. This seemed quite simple, just make the rails or tails a bit larger so the knob and router could fit on top. 

While pondering this it it occurred to me that perhaps these two designs could be combined into one. So here's what I came up with. Right now my router table is down because I'm in the middle of building a router lift and don't want to wait until that's done before making these shelves. I have some 1/2" baltic birch left from my truck drawer build, so I've designed this out of two layers of 1/2" ply glued together. The sketchup doesn't have the seam in the middle because it was easier to draw as a single 1" heigh block. But imagine this is two pieces of 1/2" with the dados and rabbits cut before glueing it together.

What do you think, will this work?


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## DesertRatTom (Jul 3, 2012)

Interesting idea. Looks a little frail to me though, and maybe a challenge to store. Proof is in the making though. Let us know how it works.


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## DesertRatTom (Jul 3, 2012)

I have a Dado Wiz for this purpose. Attaches to a track. Really like it, but you have to remember to put a slip of paper in to allow space for glue. I have a little gash in mine from learning the lesson to NOT lift the router up while it is still running.


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## MT Stringer (Aug 15, 2012)

Here's mine. Works great.
http://www.routerforums.com/jigs-fixtures/49738-exact-width-dado-jig.html


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## Everend (Mar 15, 2013)

DesertRatTom said:


> I have a little gash in mine from learning the lesson to NOT lift the router up while it is still running.


 I think everyone has to learn that one the hard way. It's funny how often I've forgot that lesson.


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## Everend (Mar 15, 2013)

The one question I'm pondering is if this will work well enough as the exact width Dado jig or if I'd be better off building both.


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## Cherryville Chuck (Sep 28, 2010)

Looks good if stiff enough as mentioned Everett but a point to remember is that unless you are using it in some way for lap joints the the amount of adjustment needed will typically only be between 1/4 and 3/4".


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## MT Stringer (Aug 15, 2012)

Here is some more thinking...and action. I built a simple one time use jig for cutting shelf dadoes for kitchen cabinets. Actually, if I need to use it again, all I have to do is remove the screws, adjust the width for the next work piece, and screw the block back in place.

Lots to read on a cold day! 
http://www.routerforums.com/jigs-fixtures/103234-thoughts-about-my-exact-width-dado-jig.html


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## Everend (Mar 15, 2013)

In the picture all four sides are the same length because I just made one side, made it a component and made three copies. In reality I'll make two sides shorter.

For storage one could separate the joints and set the pieces on a shelf in parallel.


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## Everend (Mar 15, 2013)

Here's another pic with sizes.

There is a 1/2"x3" vertical mating surface and 1/2" horizontal mating surface on the tenon in the tslot. With 1/4-20 bolts holding it tight into the t-slot, I expect it will be quite stable. 

Off to the shop, I'll post again when I get it built!


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## Everend (Mar 15, 2013)

Delay for raking leaves.


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## tomp913 (Mar 7, 2014)

I've seen various designs for adjustable jigs for routing recesses, thought that they were a little complicated - the only time I used one it was made with pocket screws and not adjustable.

Looking at the latest concept, it occurred to me that there would be a way to make this fairly simple,

- On the long edge of the strips, cut a T-slot for a 1/4" bolt for the whole length.

- On the short end of each strip, cut a tenon that fits into the T-slot. There will be a short portion of the tenon missing over the T-slot.

- Buy (4) countertop connectors like this Supports & Brackets - Recessed Worktop Connector - Saves Time Connecting Work Surfaces by Hafele | KitchenSource.com

- bore a 35mm dia hole in the face of the strip at the end with a tenon, and a 1/4" dia hole in the end through to the 35mm hole

- Place the "fastening element" in the hole and the 1/4" bolt in the T-slot, feed the bolt into the strip and attach the nut.

This will work for 3/4" strips, the 35mm hole will go all the way through but shouldn't present a problem after the initial assembly. Optionally, you could use 7/8" or 1" material and bore a blind hole that would support the fastening element - the drawback would be need for a longer bit to compensate - but I really don't see that as being required. The "open hole" on the top also shouldn't be a problem as the router base would pass over with no problem.

The downside of any jig like this is the open slot on the inside surface - not a problem if you're using a template guide bushing, but could present a problem with a pattern bit. Using a jig like this with a template guide and using the part being inletted as a pattern, I just put a shim on all four sides of the part with the shim thickness equal to 1/2 the difference between the guide bushing OD and the bit OD - eg using an 1/8" thick shim with a 3/4" OD bushing and a 1/2" router bit.

I tried a free-hand isometric sketch and it got sloppy, probably easier to make it in SketchUp but the concept is actually pretty simple.


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## Everend (Mar 15, 2013)

tomp913 said:


> I've seen various designs for adjustable jigs for routing recesses, thought that they were a little complicated - the only time I used one it was made with pocket screws and not adjustable.
> 
> Looking at the latest concept, it occurred to me that there would be a way to make this fairly simple,
> 
> ...


Tom,
You mostly reiterated the design I've been talking about here. You're right you must use a template guide, a pattern bit will not work well here. The one I'm building will have the offset on the lower face so it's zero clearance for the bit and giving the option of using this as a zero clearance dado jig too. 
I saw some of those counter top bolts earlier today while sorting through my hardware bin. I could use that bar as the washer to make it unnecessary to use a chisel to square off the open hole. I agree the open hole should not effect the router.
I honestly don't know why nobody has posted the idea of using a tenon before.


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## tomp913 (Mar 7, 2014)

Everend said:


> Tom,
> You mostly reiterated the design I've been talking about here. Your right you must use a template guide, a pattern bit will not work well here. The one I'm building will have the offset on the lower face so it's zero clearance for the bit and giving the option of using this as a zero clearance dado jig too.
> I saw some of those counter top bolts earlier today while sorting through my hardware bin. I could use that bar as the washer to make it unnecessary to use a chisel to square off the open hole. I agree the open hole should not effect the router.
> I honestly don't know why nobody has posted the idea of using a tenon before.


 @Everend

I have a little problem understanding your sketch, but I understand the concept of a rabbet in the top, inside edge of the strips to accept the body of the template guide (there are a couple of designs of zero-clearance rabbet jigs that use this idea) but you would have to increase the thickness of the strips to include this rabbet, and so offset the T-slot and tenon to the underside to compensate. Additionally, you would still be stuck with the 35mm hole being drilled thru so that the nut can be tightened from the top - although I guess you could flip the jig over and shim the part up off the worktable while you're adjusting and tightening the nuts.

I had the idea too that making the strips out of some relatively hard and stiff "plastic" - maybe phenolic or similar - may make a more durable assembly than hardwood or BB plywood although the extra cost may not be warranted unless you're going to get a lot of use out of the jig.

The idea of the tenon was to automatically align the strips across the face at the joint to eliminate any twist as the screws are tightened as any misalignment may interfere with smooth travel of the router.

I've used the countertop fasteners to bolt a rail to a workbench leg and it works well - you can get two connections out of each unit, using just the two half circles and the nut and furnishing two bolts and an additional long nut.


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## CharleyL (Feb 28, 2009)

When making dados for shelves, etc. I use a jig that I built very similar to the one that MTStringer posted. This jig makes it easy to get perfect fitting dados by using the shelf piece to set the jig spacing, and if the jig is designed right, it squares itself to the edge of the board being cut like a T square.. Then a top bearing type mortising bit can be used to cut the dado while riding within the slot in the jig. If made sufficiently large, spring clamps can be used to hold it in place.

When making rectangular pockets, like those in an electric guitar body or similar, I use a jig that I made similar to the one in your original post. This isn't the best jig for making shelf dados because, to me, it's too fragile for this. It serves a good purpose, but not for making shelf dados. It can't square itself to the board being routed either. I always make the adjustments to get it the right size both X and Y, and then use double sided tape to hold it in place while using it. 

Charley


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## Everend (Mar 15, 2013)

I haven't quite finished it but here is a couple photos so far. I ended up using the HD Sandee wood plywood instead of BB since it was what I found when I went digging for appropriately sized scrap. The reference edges are clean but there are a couple voids or tear outs in the t-slot.


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## vindaloo (May 30, 2009)

That seems like a lot of work in comparison to making the one Mike has made.


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