[OP]
Member
I have only been using pocket screws so far for the projects I have been making. I would like to use M&T joints on my next project. My question is should I use my drill press with a forstner bit or should I use my plunge router? If I use the router is there a jig to make sure the mortise is straight?
Member
John,
Both are great methods, depending on what type of mortise youwant to make. Here's a great article on a sure fire home made jig:
http://www.tools-for-woodworking.com...n=Custom&ID=29
Have fun!
Maurice
Contributor
John. Here are a couple of jigs that I use. One is home made the other is store bought. Basically anything that can give you a repeatable straight line can be used. I probably have another 3 or 4 in addition to these.
[OP]
Member
Thanks for the help.
Member
I might also suggest learning to make the mortises by hand with a chisel. It's not very hard and if you don't have to make a large quantity at a time, it's very quick. Bob Smalser wrote an excellent article on how to do it.
Contributor
There are hundreds of way to do this but I concur, unless you have a bunch I would recommend doing them by hand. it will help in your understanding of the joint much more so that using machines to begin with.
Keith
Member
If you do them by hand, first use a drill press with a bit almost the size of the mortise and drill out most of the wood before going to the chisels. It really is not difficult, especially if the mortises will not show and they don't need to be perfect. My second choice would be a router with a jig or on a table with a fence. Take out a little at a time and use a spiral bit to move the excess wood out of the mortise.
If you want to invest in this, buy a "multirouter" system which allows you to use a router horizontally to really hog out the extra wood and get perfect mortises.
[OP]
Member
This is what I am leaning toward (drill press method) for this next project. I will likely try the router technique on the next and see which I prefer. I looked at multi routers, the cost far exceeds my M&T needs. The one that I saw was $2,695!!!!!!Originally Posted by Ellen Benkin
Member
John,
If you like the router way, check out the latest FWW issue. There is a great article on making your own slot mortiser (horizontal router set up). It's a neat, simple, inexpensive system the author came up with. I've got it on my list of "things to make for the shop".
Maurice
Contributor
John. What type of M&T joints do you need to do, and how many?
The project that I'm currently working on has over 300 M&T joints, of various types. There are many ways to do them. The key though is repeatability. The home made jig in my first post is pretty accurate, but very repeatable for router made mortises in the edge of a board. The second is a benchtop mortiser with and XY sliding vise, very accurate and very repeatable. I have others for thru mortises, thru stepped mortises, routered Dado's in large stock.
One very easy device is a center finding base plate for a router. It will put a mortise into the middle of a piece of material, and only cost a few bucks.
The M&T Joint is the primary joint in furniture making. The better it is done the better the overall joint integerity will be. A loose fitting M&T joint can be made with void filling glue's, but the better fitting the joint to begin with, the better off you'll be in the long run. An M&T joint should basically hold itself together.
There is also a "rule of thumb" for sizing tenons and mortises. hopefully I get this right, If not someone please correct it for me. A tenon should be 1/3 the thickness of the mortised material, the tenon width should be 5 times the thickness of the tenon., but not exceed the width of the material the mortise is in, in this case the tenon should be split and the split should equal the thickness of the mortised material as a minimum. The length of the tenon is 5 times the thickness ( The Japanese method is to have the tenon length be just slightly less than the width of the mortised material). There are also some "rules of thumb" for tenon location with respect to the end of the mortised piece. Remember though that these are rules of thumb, and not etched in stone. This is for a basic M&T joint, not a stepped or haunched M&T joint.
Sharp chisels are a must, all M&T joints will need to be cleaned out to some extent.
Make your mortises first. It's easier to resize the tenon than the mortise.
[OP]
Member
I have 16 M&T joints to make. So if I am using stock that is 3/4" thick and 1 1/2" wide my tenon should be 1/4" thick and 1 1/4" long. Is that correct?John. What type of M&T joints do you need to do, and how many?
The project that I'm currently working on has over 300 M&T joints, of various types. There are many ways to do them. The key though is repeatability. The home made jig in my first post is pretty accurate, but very repeatable for router made mortises in the edge of a board. The second is a benchtop mortiser with and XY sliding vise, very accurate and very repeatable. I have others for thru mortises, thru stepped mortises, routered Dado's in large stock.
One very easy device is a center finding base plate for a router. It will put a mortise into the middle of a piece of material, and only cost a few bucks.
The M&T Joint is the primary joint in furniture making. The better it is done the better the overall joint integerity will be. A loose fitting M&T joint can be made with void filling glue's, but the better fitting the joint to begin with, the better off you'll be in the long run. An M&T joint should basically hold itself together.
There is also a "rule of thumb" for sizing tenons and mortises. hopefully I get this right, If not someone please correct it for me. A tenon should be 1/3 the thickness of the mortised material, the tenon width should be 5 times the thickness of the tenon., but not exceed the width of the material the mortise is in, in this case the tenon should be split and the split should equal the thickness of the mortised material as a minimum. The length of the tenon is 5 times the thickness ( The Japanese method is to have the tenon length be just slightly less than the width of the mortised material). There are also some "rules of thumb" for tenon location with respect to the end of the mortised piece. Remember though that these are rules of thumb, and not etched in stone. This is for a basic M&T joint, not a stepped or haunched M&T joint.
Sharp chisels are a must, all M&T joints will need to be cleaned out to some extent.
Make your mortises first. It's easier to resize the tenon than the mortise.
Contributor
Those proportions would make a nice strong joint. You will want to cut the mortise 1 1/4" deep, but the tenon should be a 1/16" shorter to allow glue to squeeze out in the bottom of the joint. If you have trouble getting router bits that long you could go to 1" deep mortise and 15/16" long tenon.
For simplicity a lot of people will use a 3/8" wide mortise, and 3/8 thick tenon, but again 1/4" should be fine. Remember it's a rule of thumb.
I've got a few joints here. The first two pictures show a joint along the proportions of yours. This will be a load bearing joint, there are however 20 of these joints along a 31" length and 21" width, so I could cheat a bit. The last two pic's show a definite deviation. This joint will bear no load. In fact a biscuit would have worked just fine. It needed to be shallow to allow a 1/4-20 rod to run the length of the mortised piece, 16", and join 2 sections 32" long to sandwich a shelf. This project is still in the rough, and there still remains some "tuning up"
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