lock miter bit

[Bob Blue]

I just registered for this forum this morning and am looking for honest answers to honest questions (which i was not getting on another forum).

Has anyone used the 45 lock miter bit on your router table , if so how do you like it ?

Thank you

Have a nice day !

[Chris Padilla]

Hi Bob...Welcome to SMC! We hope you hang around...you should find your answers here and also do some searching...you'll find a lot of stuff to read.

I have used the lock miter bit on my router table and while I like it, I have a difficult time setting it up correctly. I'm an educated man but this bit infuriates me and I must make 8' of test cuts before I get it right and I've read lottsa stuff online on how to set this bit up but I guess I just don't get it.

I have trouble using it with plywood (or at least the plywood I have), the cut of the bit with the plys goes fine (usually this means the plywood face is flat on the router table) but the cut perpendicular to the plys (usually the means the plywood face is against the router table fence) is where I suffer a lot of tear-out. After I did it, it kinda makes sense why this cut doesn't work well on plywood...the plys simply have no support.

On hardwood, this wouldn't be an issue but I've yet to use it on hardwood. One of these days I'll "get it" on this bit...one of these days....

[Hank Knight]

Bob, welcome to the Creek. I think you will find lots of friendly, helpful woodworkers here.

I have both a "standard" size and a small size lock miter bit. I don't use the standard one very often, but I find the small one useful for drawers. I sometimes make utility drawers from 1/2" baltic birch plywood and the lock miter bit makes the job easy and produces a strong joint.

[Greg Scott]

Bob,
I've used a 45 lock miter bit and loved it. I wanted a seamless joint on a gun cabinet that I built and didn't want to rely on a regular miter joint. I bought the bit from Woodline. I'm sure others will say Woodline does not sell the same quality bits like CMT and Whiteside but for an occasional user the are great because they are very inexpensive.

Attached is the cabinet that I used it on. You can't see it very clearly but it is the joint between the side panel and the faceframe.
Greg

[Mike Cutler]

Bob. Welcome to Sawmill Creek, pleased to meet ya'.
I have used the lock mitre on a number of occasions. It's a little fussy to set up at first, getting the height and didstance properly aligned.
I have to admit that it's a kind of nerve racking bit. It takes off a lot of material and there is a lot of chatter. The bit tries to push the material out and up at the same time.
I align the bit for a full cut pass and then put a spacer piece of wood against the fence to remove the material in 2 passes. Some people precut the first 1/4" of the miter also. There is also a "sled type" jig that can be made to give you more control. The bit should also run at lower speeds. I run mine with a PC8529 set at the ~10000 rpm setting.
I have found that it is easier to set the height first, and then the distance. Make two complete miters on two seperate pieces of material. Flip one over and align the mitre. move the miter bit in the direction of the error, one half the amount of the error to resolve the misalignment. You may need a vernier indicator to accomplish this. When you finally have it aligned keep the pieces for templates to speed up the alignment later.
I've never been good enough to set it up for use on two pieces of material with different thicknesses, but it can be done. If you plan to use the miter on the same thickness of material, ensure that the material is all the same thickness.
There is a book titled "In The Craftsman Style" where this is an example of the bit being used to make the legs on Stickley reproduction furniture. Iy may be worth looking at.
Once again, Nice to meet ya'

[Jay Knepper]

I've used a big one to make thew column of a hall tree, or "costumer", out of qswo. It was 24+ feet of a very heavy cut, and really pushes the capabilities of a router (vs. a shaper).

You have to lock everything down or it will move. Tightly secure the fence and the router's height adjustment. Otherwise they will move.

I did not find it to be too bad to set up.

Once you've made the cut, it's a great joint--strong and easy to clamp.

[Dave Carey]

I've also read that it helps to slow the router down considerable. Haven't tried that yet but will inasmuch as my experience to date is as frustrating as the other cases reported here.

[Hank Knight]

I have trouble using it with plywood (or at least the plywood I have), the cut of the bit with the plys goes fine (usually this means the plywood face is flat on the router table) but the cut perpendicular to the plys (usually the means the plywood face is against the router table fence) is where I suffer a lot of tear-out. After I did it, it kinda makes sense why this cut doesn't work well on plywood...the plys simply have no support.....

Chris, I have tear-out with the lock miter bit in plywood too. I use a backer-board to eliminate some of it. With drawers, I cut a plywood panel to the proper length and wide enough to rip the all of the drawer pieces leaving some waste. I cut the lock miter profile on panel edges and then rip the drawer sides to the proper width, leaving the tear-out in the remaining waste.

When I cut the dados for the drawer bottoms, I found that the dado blade (or slot cutter in a router table) damaged the locking tenon left by the lock miter bit. I now chisel the dado through the tenon first, wide enough to make sure the blade has clearance and won't chip the tenon off. One would think that the tenon in plywood would be too fragile to do much good. It probably serves more for alignment than strength, but once the joint is glued up, it is very strong.

[Jay Knepper]

I forgot to mention that it is also critical to use hold downs, both vertical and horizontal, when making the cut.

[Michael Ballent]

I have used them in the past and just dread using them... Very fussy to get it set up right, and your wood has to be dead flat as well so if you prepped some wood last week and it was flat then and moved/twisted over the week you will probably have problems... better off with some other joinery IMO :D Did I mention that I do not care for them.

[martyphee]

I'm about to use it on my son's bed posts. 3" square using 3/4" walnut. I did some test pieces on my router and it did alright. I'm going to try it next on my 5hp PM shaper. I'm hoping the shear mass of the shaper will help give a smoother cut.

[Jim Hinze]

I have the small CMT lock miter bit and have used it on 2 projects. Like everyone has said, they are tempramental at best to setup, but once setup, turn the router speed down and feed slow. Have a sacrifical board in the back to avoid tear out...

They do produce a strong seemless joint (when setup properly).

[Richard Wolf]

Let me add one thing, you can not precut the miter but you can remove some material on the table saw first. If you do this it will reduce tearout and give much better results.

Richard

[Dave Falkenstein]

...the cut perpendicular to the plys (usually the means the plywood face is against the router table fence) is where I suffer a lot of tear-out. After I did it, it kinda makes sense why this cut doesn't work well on plywood...the plys simply have no support.

Chris - Next time try making a scoring cut with your table saw before you cut the vertical pieces with the lock miter bit. I had the same problem with a drawer lock bit, and the scoring cut sloved the problem.

[Don Baer]

Geez you guys are good. I never treid one before but ow I need to go out and get one of these. It will solve a lot of my joining problems. I guess I'll spend my weekend practising with it so when I do my next project I'll be ready.

:rolleyes:

[Sam Blasco]

I really love the lock miter. I only found it fussy the first time. I use this joint quite abit, makes miter glue ups a breeze. There are several different styles out there from many manufacturers, with different approaches. Could be why there are many different responses as to ease of use. This would be an interesting area for a mag to test and report.

[thomas prevost]

Many of the manufactures sell setup blocks for getting the fence and height right. I thought I would be bald before I got it right. then I purchased the set up blocks. 5 minutes and one or two test cuts and I am ready to go.

OR when you do get a setup correct make a few sample blocks and keep them for the next time setup.

[Don Selke]

I have to agree with the set-up blocks as mentioned. I purchased this bit and had some problems setting it up. When I finally got it set up the proper way and made some cuts for a aquarium cover, I was amazed how easy it was to glue the mitres together. When you get it, make sure that you follow the instructions and allow yourself plenty of stock for samples. MLCS has a good instruction sheet on there web site for proper set-up and use of the bit. By the way, I do not have a lock mitre router bit, it is a 3 wing shaper cutter that I bought at a garage sale.

[John Lucas]

Don,
Would you believe that it is one of my favorite router bits. Once you know how to set it up (easy), it really gives a great joint. If you look at my main menu, you will see 7 different stories where I used and it shows how to set it up.
http://www.woodshopdemos.com/menu2.htm

You will also see how I use it with particle board (white melamine) and plywood. In the articel "how to set up" it shows my A/B Plan which is foolproof for setting up.
http://www.woodshopdemos.com/cmt-lmc7.jpg