# 45-Degree Lock Miter



## pcorona (Aug 21, 2015)

Given up on this joint for awhile...trying to make a square flag case..cannot cut the uprights. No matter what I try I get kickback.....time to rethink


----------



## Jerry Bowen (Jun 25, 2011)

Paul,
I understand your frustration, but I encourage you to stay with attempting to get it right. The lock miter joint is a great choice and while it can be frustrating, it's worth messing with until you get it right.

I assume that you have the setting right and what you are dealing with is just the feed and as you say the "kick back" issue.

Are you cutting end grain or with the grain. It's the end grain cuts that I have had the most, but not all, of my problems with. 

What is the width of the workpieces that you are cutting into if the cuts are end cuts.

If the width is narrow, less that three inches, I have problems and so I try to make the end cuts with wide stock and them rip the work pieces to the correct width after making the cuts. 

Let us know more about what is going on in regard to, your set up, is it correct, what is the width of the workpieces if you are doing end cuts. I keep assuming that you don't have problems when cutting with the grain, but that is only an assumption, so let us know know more.

Also, again, my assumption, but need to be sure, do you have your router running at it's lowest speed?

Will wait go hear from you,

Jerry


----------



## paduke (Mar 28, 2010)

Paul, Are you using featherboards? The bit will try to lift the material off the table and then grab it Like Jerry said keep trying (on scrap the same thickness ) and you'll get the hang of it


----------



## Cherryville Chuck (Sep 28, 2010)

In my uploads I show a Sketchup drawing of a board clamped onto your vertical piece that rides on the top of the fence. That will help keep it stable.


----------



## bcfunburst (Jan 14, 2012)

*45* Lock Miter*

I can't say I have ever had any kick back while using this bit. I do know it can be a huge, time consuming problem getting the correct set-up for the cut, unless you have the set-up blocks. I refused to pay the money for set-up blocks. When I finally got the correct setting, I made several sets of blocks out of different hardwoods and different thickness' for future set-ups. THAT has saved me SO much hassle since then!! I have only used the lock miter bit in hardwoods, so far. Such a large cutting bit needs to be run at your slowest speed, agreed.


----------



## pcorona (Aug 21, 2015)

week of work and back to it.....cutting end grain in cherry...been pretty tough. Using feather boards and made a zero clearance fence guide......moved on to a "rabbeting miter" bit set from MLCS...that is a whole lot easier to control.....

think I need to get a different insert for my router plate and drill that insert to exact size for the lock miter bit making it also zero clearance .....think I was getting wobble from that. And was cutting at the lowest speed. Jerry's comment dead on..was trying on 3" material and think that is too narrow. Will work on wider pieces when I move back to that bit and as suggested then rip to size. Thanks for that observation.


----------



## CharleyL (Feb 28, 2009)

For easy success in setting up a Lock Miter Bit, the Lock Miter Master Jig from Infinity Tool is the easy way to get the setup right very quickly and easily. I had terrible luck with these bits until I got one of these jigs to help me with the set up. 

To use it, you just find the exact center of each board that you want to join, put the Lock Miter Master jig on the router bit (magnets hold it in place) and then set the bit height or your fence (depending on which board you want to cut) for it's center line to match the long line on the jig (either the horizontal line or the vertical line, depending on which board you want to cut). The other lines are for making some different variations of the joint (explained in the instructions). Finding the exact board center is also easy and explained in the instructions.

https://www.infinitytools.com/lock-...FjetXM34_gLYb2lppzpWdcftd7kXwCUGiPBoCHU_w_wcB

Once set, and with feather boards in place, you can make your first joint and have the two boards fit together so close that many times they will be perfect with just these first test cuts. 

I could never make this joint, until I got my Lock Miter Master Jig. Now it's quite easy to get my router table set up to make the joint. You will be making a deep cut on end grain, so a good sacrificial push block is an absolute necessity to keep the stock moving straight past the bit and to minimize tear out of the trailing edge of the work. Sometimes on solid stock or cabinet birch plywood the tongue part of the joint will chip and not look too good, but the joint should go together very well anyway. Usually this ragged area is in the middle of the cut, so it isn't seen at all when the joint is glued together. These joints are very strong when put together properly with good glue. You will be very pleased with the end result, and with a little practice you will be able to make these joints very quickly. 

I'm just a happy customer with no connection to Infinity, other than being one of their customers.

Charley.


----------



## DesertRatTom (Jul 3, 2012)

@CharleyL thanks for the reminder, I have that jig but forgot it was there. I'll have to give it a try. It is a tiny thing, I hope I can still find it.


----------



## hawkeye10 (Jul 28, 2015)

CharleyL said:


> For easy success in setting up a Lock Miter Bit, the Lock Miter Master Jig from Infinity Tool is the easy way to get the setup right very quickly and easily. I had terrible luck with these bits until I got one of these jigs to help me with the set up.
> 
> To use it, you just find the exact center of each board that you want to join, put the Lock Miter Master jig on the router bit (magnets hold it in place) and then set the bit height or your fence (depending on which board you want to cut) for it's center line to match the long line on the jig (either the horizontal line or the vertical line, depending on which board you want to cut). The other lines are for making some different variations of the joint (explained in the instructions). Finding the exact board center is also easy and explained in the instructions.
> 
> ...


Charley that is pretty neat the way it works. So simple why didn't I think of that.


----------



## harrysin (Jan 15, 2007)

Once the test piece for a particular size of wood is spot on I keep it as a jig for future quick set-up As for a zero clearance fence, I clamp a board, usually MDF to the fence then draw the fence forward through the board.


----------



## CharleyL (Feb 28, 2009)

hawkeye10 said:


> Charley that is pretty neat the way it works. So simple why didn't I think of that.


I thought so too, and it works with all of the 45 degree lock miter bits, no matter who made them. 

After I bought the Lock Miter Master jigs and had used them for a while I managed to meet the inventor. He is also the inventor of the Incra I-Box jig, and a very interesting person to talk to. I keep waiting to see what he's going to come up with next, but he's been very quiet lately (maybe he's too busy working on "Next", whatever it is). 

Charley


----------



## pcorona (Aug 21, 2015)

I'll check it out....thanx !


----------



## pcorona (Aug 21, 2015)

I did the same thing....


----------

