Another locking mitre joint thread.

[keith micinski]

So after reading all of the threads on the problems people have been having on setting up a Locking Mitre bit I decided to give it a try. I have been wanting to get one anyway because I want to build a steamer trunk and want to use locking mitre joints to build it. I also purchased a small grizzly shaper a few months ago and haven't really had the time to mess with it so I took this as an opportunity to buy some cutters and give it a shot. In hindsight learning how to use the shaper and learning the locking mitre bit probably should have been two separate things :) I used some of these other threads to figure out that the first thing you need to do is find the center line of the two pieces you are joining together. I decided to use two 3/4 pieces to not only make it simpler but also because 99 percent of the time this is what I would be doing. After finding the center of each piece buy marking a line at 3/8 I took the piece and eyeballed it up on the center line of the bit for height. I used Alans drawing to figure out the center line of the bit is the center line of the 45 degree part of the cutter. I then flipped the piece up on the fence and eyeballed the edge of the piece with the outside of the bit. I made a test cut and saw that I had the bit a little to low so I made another test cut using the same piece and still needed a little more height on the bit so I made third cut and the height of the bit was perfect. I noticed that there was a slight lip on the pieces on the end so I bumped the fence back a hair more and decided to go ahead and cut a joint and see what I came up with. I made the cuts and the joint was really close but I still had a small ridge on the fence piece so I went ahead and bumped the fence back just a hair more and made another cut I think the joint came out perfect and extremely happy with the result. I used my Wixey digital height gauge and took some measurements to set the bit up as far as height and depth and I also now have two template pieces to use as setup blocks. I figure in the future I should be able to setup the bit using my set up blocks and then make one test cut and probably have it dialed in only needing a small adjustment. Using my shaper on the other hand is going to take a little more work. There were some steps overlooked in this process but they had to do with messing around figuring out the shaper and the fence. I am going to redo some of that stuff before I use the shaper again but I really am thinking now that I have those initial pieces setup is going to be a breeze.

[Joe Scharle]

Actually pretty simple, isn't it!

[Rod Sheridan]

Hi Keith, nice to see you that were able to solve the issues with the setup.

I'll suggest The Spindle Moulder Handbook by Stephenson, it's the only up to date shaper book I've found, well worth purchasing.

One item that helps with lock mitre joints on the shaper is a continuous one piece fence that you make for each different cutter you use.

Regards, Rod.

[johnny means]

What no $50 set-up blocks? Preposterous! :-D

[Mark Burnette]

Grizzly cutter?

[keith micinski]

Grizzly cutter?


Yes it is a grizzly cutter I am becoming a big grizzly man I guess. My next project is to make a new fence system for the shaper. I hate the two piece offset design. I have never needed one before and it's more of a hassel then it's worth to me. I get that there are advantages with certain types of cutters but I dont need them. I have to figure something out for mounting it to the pieces of oak I have on there now because the castings on the shaper hood are ridiculously not square and those faces had to be jointed flat and parallel.

[Alan Schaffter]

Very nice looking joint!!

If anyone is using the "center of profile" method for setting the lock miter bit height and fence position, you need to be aware of one thing. Depending on the brand of the bit, the center of the profile may not be halfway between the top and bottom of the 45° cutting edge. It all depends on how the top and bottom of the bit are milled. That was a weakness of the tip doing the initial setup with a Wixey that appear last year(?) in FWW(?).

Once you have the bit and fence set for a good joint in one thickness of stock, a Wixey is an excellent way to ensure the setup is correct the next time with the same thickness stock.

[keith micinski]

Very nice looking joint!!

If anyone is using the "center of profile" method for setting the lock miter bit height and fence position, you need to be aware of one thing. Depending on the brand of the bit, the center of the profile may not be halfway between the top and bottom of the 45° cutting edge. It all depends on how the top and bottom of the bit are milled. That was a weakness of the tip doing the initial setup with a Wixey that appear last year(?) in FWW(?).

Once you have the bit and fence set for a good joint in one thickness of stock, a Wixey is an excellent way to ensure the setup is correct the next time with the same thickness stock.


I forgot to mention that I found the center line of the bit by making two cuts and placing them together to see if they were flush or if they were offset. They were offset so I took the difference and cut it in half and raised the bit that much. You really don't need to know the actual center of the bit just make a test cut and adjust from there.