Making M & T’s joints has been an evolution for me. I thought I would share what I have learned so far. Like many woodworkers I started out with various combinations of drilling and chiseling for the mortise. For tenons I tried a variety of fixtures for holding the piece to cut with the table saw. After a while you get better and faster at this, but ultimately it’s a fairly slow process both for setup and operation.
Next was a shop made fixture so I could use a router for the mortise. It was basically a slot with stops to control the length. The width was as controlled with a combination of guide bushings and different diameter router bits. Doing it this way for the mortise was faster and more consistent, but the mortise corners were rounded so I would still have to either use a chisel to square it, or round the corners of the tenon. This worked pretty well for the mortise, but didn’t improve the tenon making.
Next up I found a good deal on a used Leigh M & T (FMT Pro Mortise & Tenon Jig - Leigh Tools a Lee Valley Tools Company). As of today, these are more expensive than a Domino, (but they used to be a little less). Follow this link if you would like to see a video of how it works (Leigh Videos - Leigh Tools a Lee Valley Tools Company). It is a similar concept to the PantoRouter at least in the way it does M & T. It uses snap in guides combined with various router bit diameters to make almost any size you need. The guide works for cutting both the M & T. A tapered pin is used to ride on the guide and can be adjusted up or down to precisely dial in a perfect fit. The setup time depends a little on what you are doing. For simple chair rails, it’s straightforward and once you learn what kind of fit you like, it’s a matter of lining up the center mark and setting stops to repeat the process. If you’re making double tenons or a size bigger than the standard guides, it’s going to take a little longer. The precision is amazing and when you go to glue everything together, everything fits perfectly and is square.
Lastly, I broke down and got a Domino. Of course it only does loose tenons but in most cases it can work where you want a M & T joint. Additionally, it can work in many cases that a M & T cannot, like joining boards. The setup time is hands downs faster than anything I’ve tried so far and the consistency is just as good. I still prefer the Leigh M & T jig for things like the chair parts shown above but for overall flexibility and ease of setup the Domino is an excellent tool. The only thing I don’t like about the Domino is the size of the mortise it makes on the middle setting. The tight setting makes a tight fit but the middle setting makes the mortise about 1/8” bigger. I don’t like that because it allows the pieces to move during glue up. Unfortunately you can’t always make joints with tight settings on both sides or it might be difficult to get together unless you’re alignment is perfect. I typically use the tight setting on both sides but on one side I will run the hole twice and offset the alignment on the second hole about 1/32”.
I was hesitant for a long time to get a Domino due to the cost. Often times I justify not getting something expensive by saying it’s not worth it and I can do the same thing with the tools I have. I still would not argue with anyone over the justification of the cost of a tool because it’s a personal choice and doesn’t need to be justified. We’re all at different stages of life so what is right for me now is different than it was 5 years ago.
Here’s an examples of where I first used the Leigh M & T jig, then switched over to the Domino. The Domino was much quicker to setup and did just as good of a job, and I believe will be just as strong.
This is what the center piece looks like when I used the Leigh M & T jig. (Forgot to take a picture before I put it together). Note, the bottom will be cut straight, I wanted perfect alignment on the curved joints.
This is what it looks like using the Domino.
Next was a shop made fixture so I could use a router for the mortise. It was basically a slot with stops to control the length. The width was as controlled with a combination of guide bushings and different diameter router bits. Doing it this way for the mortise was faster and more consistent, but the mortise corners were rounded so I would still have to either use a chisel to square it, or round the corners of the tenon. This worked pretty well for the mortise, but didn’t improve the tenon making.
Next up I found a good deal on a used Leigh M & T (FMT Pro Mortise & Tenon Jig - Leigh Tools a Lee Valley Tools Company). As of today, these are more expensive than a Domino, (but they used to be a little less). Follow this link if you would like to see a video of how it works (Leigh Videos - Leigh Tools a Lee Valley Tools Company). It is a similar concept to the PantoRouter at least in the way it does M & T. It uses snap in guides combined with various router bit diameters to make almost any size you need. The guide works for cutting both the M & T. A tapered pin is used to ride on the guide and can be adjusted up or down to precisely dial in a perfect fit. The setup time depends a little on what you are doing. For simple chair rails, it’s straightforward and once you learn what kind of fit you like, it’s a matter of lining up the center mark and setting stops to repeat the process. If you’re making double tenons or a size bigger than the standard guides, it’s going to take a little longer. The precision is amazing and when you go to glue everything together, everything fits perfectly and is square.
Lastly, I broke down and got a Domino. Of course it only does loose tenons but in most cases it can work where you want a M & T joint. Additionally, it can work in many cases that a M & T cannot, like joining boards. The setup time is hands downs faster than anything I’ve tried so far and the consistency is just as good. I still prefer the Leigh M & T jig for things like the chair parts shown above but for overall flexibility and ease of setup the Domino is an excellent tool. The only thing I don’t like about the Domino is the size of the mortise it makes on the middle setting. The tight setting makes a tight fit but the middle setting makes the mortise about 1/8” bigger. I don’t like that because it allows the pieces to move during glue up. Unfortunately you can’t always make joints with tight settings on both sides or it might be difficult to get together unless you’re alignment is perfect. I typically use the tight setting on both sides but on one side I will run the hole twice and offset the alignment on the second hole about 1/32”.
I was hesitant for a long time to get a Domino due to the cost. Often times I justify not getting something expensive by saying it’s not worth it and I can do the same thing with the tools I have. I still would not argue with anyone over the justification of the cost of a tool because it’s a personal choice and doesn’t need to be justified. We’re all at different stages of life so what is right for me now is different than it was 5 years ago.
Here’s an examples of where I first used the Leigh M & T jig, then switched over to the Domino. The Domino was much quicker to setup and did just as good of a job, and I believe will be just as strong.
This is what the center piece looks like when I used the Leigh M & T jig. (Forgot to take a picture before I put it together). Note, the bottom will be cut straight, I wanted perfect alignment on the curved joints.
This is what it looks like using the Domino.
