# How to set up my 45 lock miter bit



## jasonallen (Dec 18, 2013)

I got this new router bit for making 90 degree joints. It didn't come with instructions. Its called a 45 degree lock miter bit. Anyway, I have it set up on my router table but I really don't know how to set the height of the bit and depth of the fence. I can get it pretty close but just not quite right. If anyone has any ideas that would be great.


----------



## ChefHDAN (Aug 7, 2010)

It is a VERY difficult bit to get set and you'll need to have some critical layout for the center of the stock and the positions of your bit. Infinity sells a jig for theirs and you can see the set up video here. Very key to also use a secondary board on top of the one your're cutting so the edge does not run into the bit and stays on the fence. I just ran mine two weeks ago and had to go back to the video to make sure I had it right. Be sure to mill a few extra pieces of stock too, because the test pieces are also going to be needed.


----------



## pottz (Sep 15, 2015)

yeah i have the infinity bit and i got the set up jig to go with it but you can make your own,just have to play with it.


----------



## RichT (Oct 14, 2016)

On the contrary, it is VERY easy to set up if you realize that there are two settings and that you can adjust them separately. Not only that, but once you've set the bit up once, by taking a couple of simple measurements, you can set it up first try on any other board thickness. No test cut required.

Here is a blog post I wrote on this topic: https://www.lumberjocks.com/RichTaylor/blog/111009


----------



## PPK (Mar 8, 2016)

> yeah i have the infinity bit and i got the set up jig to go with it but you can make your own,just have to play with it.
> 
> - pottz


I've got the el-cheapo Yonico brand bit. But yes, once you've got it set up, just keep a couple scrap cut-offs, and you'll have a nice guide to set up quickly next time.


----------



## jasonallen (Dec 18, 2013)

> On the contrary, it is VERY easy to set up if you realize that there are two settings and that you can adjust them separately. Not only that, but once you ve set the bit up once, by taking a couple of simple measurements, you can set it up first try on any other board thickness. No test cut required.
> 
> Here is a blog post I wrote on this topic: https://www.lumberjocks.com/RichTaylor/blog/111009
> 
> - Rich


Thank you for that great explanation. Now, if only I had a depth measuring tool as good as yours! I got mine set pretty well today by trial and error. Only to find out my Porter Cable router will gradually settle no matter how tight I get it. That was very frustrating. I see endless uses for this bit, but currently I'm using it to make 2×2 legs 24 inches long. That's 192 inches of cutting for 1 leg. The router settled enough that the 1st joint and the last joint definitely don't work. The only perfect joint was the first one. I don't have a router table, I use a home made one. Especially after today I'm considering buying a router table and different router, any suggestions would be appreciated.


----------



## RichT (Oct 14, 2016)

> Thank you for that great explanation. Now, if only I had a depth measuring tool as good as yours!
> 
> - jasonallen


The important thing to take away from my blog post is to set the bit height and fence as two separate operations using the two test cuts for each as described. The height gauge makes the process a little simpler, and allows you to come up with the formula for other board thicknesses, but isn't mandatory for getting the bit set up.


----------



## DS (Oct 10, 2011)

Perhaps my biggest woodworking failure is trying to set up a lock miter bit.
I'm sure I could do it, but not sure if I will run out of patience again like last time.

Sometimes other alternatives come up whilst wallowing in the depths of frustration that renders the current endeavor moot.
heheh
Best of luck to YOU tho' 
:-D


----------



## MPython (Nov 30, 2018)

I'm with Rich on this. Lock miter bits are fiddly to set up, but not impossible by a long shot. Be patient and work with it. Once you get it dialed in, make a set of templates to use the next time you use it. They will get you in the ballpark and the fine adjustments are easy. One tip. If you're milling plywood, the lock miter bit will destroy the top laminate on cross grain cuts. To avoid this, score the laminate on the cut line with a knife before you run it through the router table.


----------



## MikeDilday (Feb 21, 2017)

The way I do it is to run two boards on the router on the ends. Then butt the ends of the boards together. If the two boards are even then you are all set. If they are off say 1/16 then raise/lower your router half of that or 1/32. I can usually get it dead on after one test cut and adjustment.


----------



## bgood (Feb 24, 2019)

I made a mini sled for my router table. Using a few pieces of material the same thickness as my project material I finally found the correct settings. You can find set-up gages for these bits on the big online supplier. Ultimetaley I make my corners either boxed0(incra) or dovetail(porter-cable) these days.


----------



## RichT (Oct 14, 2016)

> The way I do it is to run two boards on the router on the ends. Then butt the ends of the boards together. If the two boards are even then you are all set. If they are off say 1/16 then raise/lower your router half of that or 1/32. I can usually get it dead on after one test cut and adjustment.
> 
> - MikeDilday


That's what I wrote in my blog. The link is posted above. There's more to it than just running the ends, you have to run the faces to set the fence.


----------



## RichT (Oct 14, 2016)

> I made a mini sled for my router table. Using a few pieces of material the same thickness as my project material I finally found the correct settings. You can find set-up gages for these bits on the big online supplier. Ultimetaley I make my corners either boxed0(incra) or dovetail(porter-cable) these days.
> 
> - bgood


That works fine if all you use is boards of the same thickness. Read the blog and you'll see that you can profile a given router bit for any thickness of wood. I put my bit in the router, make two settings based on the board thickness and it's perfect every time. I don't even bother with test cuts anymore.


----------



## bgood (Feb 24, 2019)

I use dovetails or fingerjoints now for successful joinery i my shop.


> I made a mini sled for my router table. Using a few pieces of material the same thickness as my project material I finally found the correct settings. You can find set-up gages for these bits on the big online supplier. Ultimetaley I make my corners either boxed0(incra) or dovetail(porter-cable) these days.
> 
> - bgood
> 
> ...


----------



## RichT (Oct 14, 2016)

> I use dovetails or fingerjoints now for successful joinery i my shop.
> 
> - bgood


Which has nothing to do with the subject of this thread. Dovetails and box joints are fine, but for a strong miter joint with just a clean corner, nothing beats a lock miter. As I said, setup blocks only work for boards of a particular thickness. The blog post explains how to profile the bit for any thickness of board that's within the limits of the bit.


----------



## BalsaWood (Mar 25, 2015)

Nice blog post about the lock miter. I've been using the bit for a while but when I first got it, it took me quite some time to get it setup properly and make adjustments. The more I used it, the better I got setting it up in future projects.


----------



## splintergroup (Jan 20, 2015)

lock miter bit setup


----------



## RDan (Jan 14, 2012)

If your router bits keep slipping, it may just be time for a new Collet, I also use the small O-Rings to make minor adjustments to my router bit height. Dan


----------



## AlaskaGuy (Jan 29, 2012)

Not to take anything away for Rich's blog he's done a marvelous job and it works. I though I'd throw this out there to give another possible choice/method. The device in this video came out a few years ago. It was invented by the same same wood worker that came up with I Box jig for make box joints. I remember it getting hi marks at the time in the online wood working forums.






Disclaimer, I have not personally used this setup tool.

https://www.infinitytools.com/lock-miter-master-jigs


----------



## Andybb (Sep 30, 2016)

Follow Rich's blog and the youtube vids on this. It's how I learned the technique. If it hasn't already been said, once you get a perfect fit on scrap wood use those two pieces for future templates BUT, the wood thickness has to be the same as your template. In little plastic bags I have 3 or 4 templates labeled as 1/2", 5/8", 7/16" etc. If your stock is the *EXACT* same thickness as the setup blocks you should be good to go but even then some adjustment might be necessary. Otherwise you need the height gauge and/or some trial and error and patience. I even bought Rich's Infinity Tools gauge mentioned above from him just to compare the different techniques.










Made a height gauge from a set of HF calipers.

























From my review of the bit...



> *Addendum….*
> 
> Since I got such great results with the spacer block it occurred to me that if I used a height gauge and simply adjusted the bit height and fence position by the difference from the height of the 3/4" spacer block to the height of whatever stock I was using I should be able get the same results using any thickness of stock between 1/2 and 3/4".
> 
> ...


----------

