# Keyed/Splined Mitre Jig



## James C (31 Jul 2012)

Has anyone managed to construct a decent jig for routing keys/splines into mitred box sides?

I have seen a lot for the tablesaw on the Internet, but as I work in a school, even in the holidays I think I would get into a fair bit of trouble if I removed the crown guard and riving knife.

I do have a small makita router table however, so is it possible to get enough reach on say a 3mm Diameter 12mm Height router bit through a jig and into the mitred corners?

Thanks


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## Eric The Viking (2 Aug 2012)

James C":3ujveb94 said:


> Has anyone managed to construct a decent jig for routing keys/splines into mitred box sides?
> 
> I have seen a lot for the tablesaw on the Internet, but as I work in a school, even in the holidays I think I would get into a fair bit of trouble if I removed the crown guard and riving knife.
> 
> ...



Why would you need to remove the riving knife - assuming it doesn't project above the top of the blade?
Even if it did project, for a spline sled (haven't made one yet, I must admit) do you need to cut as far as the riving knife?

I did a large picture frame with half-biscuits the other day, let in front-to-back* across the mitre joint, rather than on the mitre faces, then planed flush once the glue went off. It was a fiddle to do, but it's made the frame really strong. 

Could you rig up something with a biscuit joiner? On mine (Makita) the grippy pad round the slot is removable, meaning you could slide work past it, and it will groove much deeper than is necessary for biscuits.

Just a thought,

E.

*The orientation, I mean! They're actually let into the back of the frame and are invisible from the front. It's made of architrave moulding, and frustratingly not quite deep enough to biscuit the mitre itself in the normal way.


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## marcros (2 Aug 2012)

the sled, whether used on the ts or the router table would be much the same wouldnt it? There was a WIP- jensmith I think (look for a box she made for her dads 50th or 60th birthday). I am sure that she cut the mitre keys using the router table on an Andrew Crawford course. IIRC there was a picture of it.


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## Eric The Viking (2 Aug 2012)

marcros":1ud8lcfe said:


> the sled, whether used on the ts or the router table would be much the same wouldnt it? There was a WIP- jensmith I think (look for a box she made for her dads 50th or 60th birthday). I am sure that she cut the mitre keys using the router table on an Andrew Crawford course. IIRC there was a picture of it.



It makes a lot of sense, but there are some big drawbacks to doing it on the router table:

- all the small cutters I have are pretty short, too short for even a fairly thin box. 
I don't know of long ones being available.
- You also need a seriously high RPM to get a decent quality cut as cutting speed is determined by the radius, 
- long thin cutters (1/4" or smaller) tend to wander and/or push the workpiece around, because the initial force is at right-angles to the cut. 

Tentatively, wonder if a saw blade is a better idea for this.


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## James C (2 Aug 2012)

The riving knife on our table saw comes right across the top of the saw blade so there is not a lot of options for getting a bit of the box over.

The longest 3mm router cutter I have found is 12mm. If I can get 6mm to protrude into the corner that gives me a key travelling 8.5mm into the boxes sides using the 1:1:square root 2 rule for right angle isoceles triangles. I would be happy with that.

I guess I could cut it by hand using tenon and jewellers saw before finishing by hand.


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## Eric The Viking (2 Aug 2012)

James C":1uievb87 said:


> The riving knife on our table saw comes right across the top of the saw blade so there is not a lot of options for getting a bit of the box over.
> 
> The longest 3mm router cutter I have found is 12mm. If I can get 6mm to protrude into the corner that gives me a key travelling 8.5mm into the boxes sides using the 1:1:square root 2 rule for right angle isoceles triangles. I would be happy with that.
> 
> I guess I could cut it by hand using tenon and jewellers saw before finishing by hand.



The router bit would work, and if you make the slot in the sled with a 1/4" cutter, you ought, in theory, be able to use the entire 12mm (16.8mm along the side). 

But as I said, it'll have to be going round bloomin' quick to get a decent cut, and it'll be very hard to clear the waste with only 3mm slot.

I'd certainly experiment a lot first on scrap corners !

Hope it goes well,

E.


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## woodbrains (2 Aug 2012)

Hello,

Have you considered using a slotting cutter in the router table rather than a straight bit? You won't need a jig, just a miter fence set at 45 deg and pehaps a spelch board.

Mike.


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## Jensmith (2 Aug 2012)

Thanks Marcros. the link to the post is here. The photo is near the bottom of the page.

dad-s-60th-birthday-box-wip-t54900.html


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## James C (2 Aug 2012)

woodbrains":17yvzmc5 said:


> Hello,
> 
> Have you considered using a slotting cutter in the router table rather than a straight bit? You won't need a jig, just a miter fence set at 45 deg and pehaps a spelch board.
> 
> Mike.




Why didn't I think of that? I guess that's why I keep coming here, for some good advice!

The only issue would be cutting a key slot half way up a box, but for the bottom and the top of the lid giving a nice balance of two keys this would work well.

I began laying out the basics for a jig, but will finish it later after my other project(s).


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## woodbrains (2 Aug 2012)

James C":3j0i9qn8 said:


> woodbrains":3j0i9qn8 said:
> 
> 
> > Hello,
> ...



Hi,

Cut the middle slot after you seperate the lid. Otherwise an extension in the collet will give more reach, if the box is particularly large. You might be surprised how far up you can reach with a stadard bit, though.

Mike.


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## James C (3 Aug 2012)

woodbrains":6u9bj5rd said:


> James C":6u9bj5rd said:
> 
> 
> > woodbrains":6u9bj5rd said:
> ...



Another, why didn't I think of that moment. Awesome I will try that.


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## Eric The Viking (3 Aug 2012)

@Woodbrains: Doh (homer)! You're a genius (and I'm a numpty!).

@James C: Another favourite recommendation round 'ere is Wealden Tools for router cutters.

I mention them now because they make some odd things I haven't found elsewhere, including extra length cutters and so on. They have a good web site, but I suggest you ring them to discuss the problem, because they may know of something in their range that's just the job but not obvious.

The slotting cutter is definitely a Homer moment here, as I have one, but haven't used it for ages (since I got a biscuit joiner, in fact). The cutter in a biscuit set is 4mm, so that's your minimum slot width, but they're inexpensive and turn up on eBay reguarly, presumably because people go on to buy biscuit joiners! 

Anyway, Wealden do a range of odd saw-like cutter things and might have just what you need.

http://www.wealdentool.com/

E.


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## Steve Maskery (7 Aug 2012)

I note what you said earlier, but really, the best tool for this job is the tablesaw with a square-tipped rip blade. You you have to remove the guard and RK (or at least lower the RK below the top of the blade and it sound as if you can't do that on yours) but you design the jig to be fully guarded before, during and after the cut. As long as you don't expose the blade, you will be OK from a H&S point of view.
FWIW, I cut splines for picture frames using a sub-face on my Ultimate Tablesaw Tenon Jig, and splines for boxes on a V-shaped jig that rides in the mitre slots. Both jigs are fully guarded.
S


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## James C (7 Aug 2012)

Steve Maskery":34c16dbt said:


> I note what you said earlier, but really, the best tool for this job is the tablesaw with a square-tipped rip blade. You you have to remove the guard and RK (or at least lower the RK below the top of the blade and it sound as if you can't do that on yours) but you design the jig to be fully guarded before, during and after the cut. As long as you don't expose the blade, you will be OK from a H&S point of view.
> FWIW, I cut splines for picture frames using a sub-face on my Ultimate Tablesaw Tenon Jig, and splines for boxes on a V-shaped jig that rides in the mitre slots. Both jigs are fully guarded.
> S




Thanks Steve, I already have the complete bandsaw collection. Now it looks like I might need to get the tablesaw dvds as well.


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## Steve Maskery (7 Aug 2012)

Delighted to hear it!


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