# Folded slab joinery jigs



## BZawat (Sep 21, 2012)

Another member suggested I post pics of a couple jigs I made for my last large project, so here they are. 

First one is very simple. Was used to cut a stopped mortise in a 45 degree mitered edge to accept a blind spline. 











Pic from the back. Jig is 2 12" wide pcs of 3/4" ply ripped at 45's, glued & stapled together, with two 6"x6" 45 degree blocks for support. 4" wide plywood rail on front acts as a guide for the plunge router base. 





















I cut the 1" deep mortise in 3 successive plunge passes.


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## adot45 (Jul 8, 2013)

Now THAT's a jig. Big jobs call for big solutions!


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## woodnthings (Jan 24, 2009)

*If I didn't know what you were doing....*

I'd have no idea what you were doing. :blink: Everything in the photos is used upside down to avoid the Earth's gravitational pull ...right? OR do you have to maintain upward pressure against the "fence" at all times to keep registration? 
Your stopped mortise is at 90 degrees to the bevel, which is at 45 degrees to the work and there is no good way other than the jig to accomplish this...right? :thumbsup:


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## BZawat (Sep 21, 2012)

This one was used to cut the slots for dovetail splines. 











Started as 2 separate pieces. Plywood L's, again with 45's ripped on the edges. Removed anything that would interfere with the path of the dovetail bit thru the corner. 













Marked up a piece to show where I wanted the splines, then drilled stop & start holes with a spade bit. The horizontal center line represents the outside point of the mitered corner so has to be dead on when clamped in place. Otherwise the slots come out crooked. 











Cut the slots - which needed to be perfectly straight - by marking up the TS table and SLOWLY AND CAREFULLY dropping the plywood onto the blade. I don't recommend doing this if you're not experienced at using a table saw. Lots could go wrong. Then I attached the slotted piece to the other 2 pieces with glue, staples, and a couple screws. 

Ran a 10degree dovetail bit with a guide bushing in a 1&1/4 HP router. 











Cut splines on the table saw to match the slots as perfectly as I could get em. This was a tedious process. Glued in place, left to dry, and removed with a flush cut saw.


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## BZawat (Sep 21, 2012)

woodnthings said:


> I'd have no idea what you were doing. :blink: Everything in the photos is used upside down to avoid the Earth's gravitational pull ...right? OR do you have to maintain upward pressure against the "fence" at all times to keep registration?
> Your stopped mortise is at 90 degrees to the bevel, which is at 45 degrees to the work and there is no good way other than the jig to accomplish this...right? :thumbsup:


Huh. Here I thought the pics were self explanatory. There probably is a better way, this is just how it made the most sense to me. Maybe you can share how you'd do it. 

And yes, I kept pressure against the fence while routing, and stopped at pencil marks by eye.


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## woodnthings (Jan 24, 2009)

*I have no issue with your method ...it works*



BZawat said:


> Huh. Here I thought the pics were self explanatory. There probably is a better way, this is just how it made the most sense to me. Maybe you can share how you'd do it.
> 
> And yes, I kept pressure against the fence while routing, and stopped at pencil marks by eye.


It was difficult to picture how the jig was used without knowing/seeing the end result. I would have to think on it a while to conme up with a different let alone better method. If I come up with something I will post it here. I think the folded slab concept is totally cool and any method to secure or mortise the slabs at right angles or even splayed
would be great. :yes:


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## BZawat (Sep 21, 2012)

Yeah I guess that was definitely less than clear. For some reason I couldn't find any pics of the blind spline in place and the miter going together. Could have sworn I took some...

The folded slab style was cool to work with. The first jig took about an hour to make. I spent the better part of a Saturday on the DT spline jig & making the splines though. Lots of head scratching and cutting-fitting-recutting.


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## woodnthings (Jan 24, 2009)

*how about this ...*

Use your angled jig and fence as shown only put the jig on the bottom so the router base rides on top of the fence and the workpiece is above rather than on the botttom. To allow for thicker thickness of top material just slip a narrow spline/strip on the the fence to raise the router. This would over come the need to keep pressing or pulling up on the router to maintain registration. Gravity would help if the router is pressing down along the fence. Just a thought..... :blink:


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## BZawat (Sep 21, 2012)

Wouldn't the jig need to be 135 degrees then though? This way it could be clamped under the long point of the miter, allowing the router to ride on the fence gravity assisted. It would have to look something like this: 










That way the stopped mortise is still cut at 90 degrees to the inside of the miter. Sorry for the sloppy drawing lol

That's definitely a do-able design, just feels a little more unwieldy and more difficult to build. It does however eliminate the need to keep upward registering pressure on the fence (which by the way was a bit tiring)


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## woodnthings (Jan 24, 2009)

*you got it!*

I like it! I would add another piece on top to sandwich the work and give more base for the router. The work can be clamped with all thread rod on either side or clamps, but if I were gonna do a bunch of these I'd go for a more "permanent" jig and less loose clamps.... just me. I don't know about the 67 degrees braces and all I'd just make some end pieces, maybe a center or a few ribs and have a flat bottom to sit on the bench. This would be a real handy jig for lots of angled spline applications. Good idea. :thumbsup:


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## BZawat (Sep 21, 2012)

I built that jig kinda specifically for the application at hand. With a little more foresight at the time, I could have built a more permanent one that could be adapted easily to different width workpieces. I like the idea of a top piece & replacing the clamps with threaded rod. Loose clamps can definitely be clumsy and frustrating.


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## captainawesome (Jun 21, 2012)

Those are some very inventive jigs Brian! Not only that, but each of them performed their task flawlessly, i.e. a straight mortise and perfectly straight and square slots for the dovetails.

Thanks for sharing!


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