# Lock miter bit



## Drick (Jan 14, 2005)

Hey guys,

I recently acquired a 45 degree lock miter bit. Do y'all have any tips on how to set it up in the router to get the best joints? Thank you.

Drick


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## GoonMan (Mar 22, 2005)

Drick said:


> Hey guys,
> 
> I recently acquired a 45 degree lock miter bit. Do y'all have any tips on how to set it up in the router to get the best joints? Thank you.
> 
> Drick



Hello Drick,

I have the 45 degree Lock Miter bit. It is a pain to set up but worth the time and patience in setting it up and using it.

I did a Google search and got several set up tips on it but it was still doing alot of test pieces for getting it just right. You can also order set up blocks for the bit. I also had to make a jig to run on top of my router fence to hold the up right piece. I will look at my set tips and see what web site I printed the tips from.


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## Woodnut65 (Oct 11, 2004)

Hi: The 45 degree lock-miter bit is a little difficult to set up, because each side of the joint is presented to the bit in opposite ways. One has to be flat on the table, and the other must be flat against the fence. Therefore the hieght is critical. The first time you set the bit up run alot of samples till it's perfect. Then save the last sample that you made that was perfect, to set it up for the next time you use the bit on the same thickness of material. Hope this helps..Woodnut65


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## Gilbear (Dec 13, 2005)

I use the 45 degree lock-miter bits a lot. I believe Randy's right - the set-up blocks are definately worth the money ... good point to start from and they'll save you time, but they only get you close.
I also believe Woodnut65 is right - save the final perfect test piece as a set-up block - BUT IT'S ONLY GOOD FOR THAT EXACT SAME MATERIAL ... which is the same reason the set-up blocks can only get you close. It's the minute differences in material thickness that get ya.(By the way, if you're going to make your own setup block, once you've got it adjusted, actually use a thicker piece of material to save - it helps to have a vertical edge to set the fence against). 
In general, for height, on the flat piece, you want the upper mitered bit edge to hit right at where your material thickness intersects the fence face, and for fence distance you want the lower mitered edge to hit right at the outside material face at the table surface of the verticle piece. Another way to look at that is that the spline is centered, but the exact center is hard to establish, both on the material and on the cutter. I use the set-up blocks to start and then adjust closer by laying a straight edge along the material and raising the bit or sliding the fence. 
As you get close it can also become difficult to tell if you've gone too far because your shaving down to a mitered edge - I'll take a pencil and just lay it flat and run it along the material corner to leave me a colored edge to see.
But in the end, at least for me, it's still adjusting by eye and running a few test pieces to get it perfect. On a good day, it usually takes me 2 or 3 trys.
If somebody's got a less painful or more exact way, I'd really like to hear it - I've had no instruction, and have just sort of bumbled into doing it this way. The first time I used that bit, I almost ended up yanking it and throwing it against the wall (Instead I went inside, had several scotchs and called it a day) - but now I love em and it's gotten easier with practice.


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## Holbren (Dec 30, 2004)

Here is a video that should help. 

http://www.woodsmith.com/video/154-RouterTableJoinery.html

The two keys to success are to adjust the bit height so the stock is centered on the bit and the bit should protrode from the fence a distance equal to the thickness of your stock.

Hope that helps,
Brian


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## Gilbear (Dec 13, 2005)

Brian, nice find on the video, and you sure managed to say it in a way more concise manner than I could come up with - I couldn't figure out how to explain and ended up with diahrea of the keyboard!


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## Maurice (Sep 24, 2004)

Holbren said:


> Here is a video that should help.
> 
> http://www.woodsmith.com/video/154-RouterTableJoinery.html
> 
> ...


 Many thanks for that website, it sure solved a lot of problems for me.
Mo


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## Drick (Jan 14, 2005)

Thanks for all the great help guys.

Randy, next time you're in Baton Rouge, maybe we can get some coffee.

Drick


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## GoonMan (Mar 22, 2005)

Drick said:


> Thanks for all the great help guys.
> 
> Randy, next time you're in Baton Rouge, maybe we can get some coffee.
> 
> Drick



Hello Drick,

Let me know when you have a fresh pot of Coffee on and I will help you set up that Lock Miter bit. I live in the Baton Rouge area.  Or I will wash the old grounds of Community out of mine and make a fresh one.


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## Gilbear (Dec 13, 2005)

Just a quick follow-up - check out the following link for another spin on bit set-up

http://www.ukworkshop.co.uk/guides/lockmitre/index.php


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## BobandRick (Aug 4, 2004)

Some things to think about:

A) What makes this bit work is 1) that to interlock the pieces the bit must be a mirror cut, 2) to do this the height of the interlocking part of the router bit must be in the center of your material. This is the tricky part of the set up...once set up the first time then cut some test blocks to be used to set up the next time. Material thickness is a key part of the process and the bit must be accurate and cut a mirror image for both the horizontal and vertical cuts.

B) Once the thickness is determined as to the center of the material thickness then the fence needs to be setup with the 45 degree cutting edge coming to a sharp point on the outside face of the material. The horizontal piece is the easiest to set this up on….

During the cutting process the horizontal portion is the easiest to cut and needs to be square and tight to the fence. The vertical cut is the tricky one because once its cut on the back end of out-feed we are riding on the sharp point of the miter which is difficult and dangerous to cut. Your fence needs to be 5-6” in height and square

Here is the big tip…before cutting the vertical piece place your piece in position on the in-feed side of the fence put a support piece on top of the fence edge then clamp a support stick across the vertical piece. This support piece will ride freely on the top edge of the fence and 1) keep the vertical cut square, 2) support the cut 45-degree edge of the vertical piece on the out-feed of the fence.


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