Mortise and Tenons...

[John Grabowski]

I am looking at buying some good quality mortising bits for a cheap mortiser that hasnt gotten much use. I plan on making a table and some chairs with it very soon I was wondering what sizes do you think I should buy first and maybe even a brand name.

Thanks in advance,

John G

[george wilson]

You need to see what size you need for the chairs. I'd recommend a 3/4" bit for a table,which is the maximum size bit for the small mortisers. I made a large dining table last year,and used 3/4" tenons. It all depends upon your design.

[Paul Ryan]

I bought a cheap set from grizzly. Woodstock brand I think. They were about $25. Has 1/4, 5/16, 3/8, 1/2. Those sizes shoud do most anything for you. A little honing before I used them the tips were real sharp. The cut great and remove from the work piece easily. I expect to have to hone them every so often. I also bought the sharpening cones from Lee Valley to keep them sharp. This cheap set works great for me. Espically for $25

[John Grabowski]

I am looking at making mortises for the apron on the table from 3/4 in stock, what do you think would be the best size for the mortise and tenons?? I guess the mortises for the chairs will be from 3/4 in stock to 1 1/2 in stock. Again how thick should the tenons be?

Thanks for the help,

John G

[Rod Sheridan]

John, what is the intended use of the table, and what size is it?

What kind of wood is it, and what are the leg dimensions and apron dimensions?

If you use 3/4" stock for the aprons, the largest mortise you could use would either be 1/2' or 5/8".

It all depends upon the above factors........Rod.

[John Thompson]

Ditto Rod but... I would not go beyond 3/8" or half the thickness on 3/4" stock. As others have asked.. depending on the size of the table and it's subjection to stress.. 3/8" should be fine. If it's a lamp table or any light use table not subject to weight or stress... 1/4" would even suffice but I would use 3/8" as I tend to go more than I need.

If you are build a large dining table as mentioned by George.. I would go 3/4" which I rarely exceed except on work-benches for the shop. And I could easily as I have and industrial floor mortiser capable of 1 1/2". But.. I have no personal need above the 3/4".

And the cheap set of chisels will suffice if you don't do a lot of M & T's but.. get the set of honing cones a mentioned and use them.

Good luck...

[Chris Friesen]

I would not go beyond 3/8" or half the thickness on 3/4" stock.

Arguably the more important criteria is to not go beyond half the thickness of the piece being mortised. There's no problem with making a tenon most of the thickness of the piece being tenoned, although you want to leave enough of a shoulder to cover gaps and provide racking resistance.

[John Thompson]

Arguably the more important criteria is to not go beyond half the thickness of the piece being mortised. There's no problem with making a tenon most of the thickness of the piece being tenoned, although you want to leave enough of a shoulder to cover gaps and provide racking resistance.

Howdy Chris... I certainly agree it won't hurt going beyond half the thickness but what would be the point? You increase tenon thickness but you decrease mortise wall thickness and run the risk of blowing out the side if you use mortise chisels by hand with a siip-up. The reason "I" would not go beyond 1/2 is simply I see no need.

If "I" need thicker tenons and mortise walls for strenght.. "I" would simply increase the thickness of stock to 7/8".. 15/16".. etc. when working with stock under 1". But.. that's simply what I would do. :)

Regards...

[Chris Friesen]

Howdy Chris... I certainly agree it won't hurt going beyond half the thickness but what would be the point? You increase tenon thickness but you decrease mortise wall thickness and run the risk of blowing out the side if you use mortise chisels by hand with a siip-up.

For me the key is to try and balance the strength of the two pieces. If they're equal thickness then I agree that mortise should be no more than half the thickness of the stock.

The reason I prefer to talk about the piece being mortised rather than the piece being tenoned is that often the piece being mortised is thicker to start with. Think about a 1" thick apron going into a 3" square leg. The leg could easily handle a 3/4" mortise, so there's no point in limiting yourself to a "half the apron thickness" rule.

[John Thompson]

For me the key is to try and balance the strength of the two pieces. If they're equal thickness then I agree that mortise should be no more than half the thickness of the stock.

The reason I prefer to talk about the piece being mortised rather than the piece being tenoned is that often the piece being mortised is thicker to start with. Think about a 1" thick apron going into a 3" square leg. The leg could easily handle a 3/4" mortise, so there's no point in limiting yourself to a "half the apron thickness" rule.

Just came up from the shop and caught your reply, Chris. Thanks for the explanation as I was a bit confused as you first stated. I think we are pretty much on the same page over 1" under the circumstance you mentioned as there is plenty of wall surface and the 3/4" tenon in that case leaves plenty of shoulder.

It's really kind of hard to have a cut and dry rule for a short qoute talking about this as the circumstances of mortice size and apron size can vary so much depending on the circumstances. A common sense approach using logic after the female and male end are known is basically my rule of thumb meaning I don't really have one concerning M & T's if that makes any sense. :)

Regards...