Dining table tenon length?

[WaterlooMarc]

I'm making a dining table 72"x39.5" with 3.5" legs.

How long would you make the tenons on the apron boards? (Or how deep would you make the mortises in the legs, depending on your philosophical bent) Wood is white oak.

Thanks for the help.

Marc

Ps - the top was originally planned to be 38" but after the glue up it wound up at 39.5" to allow for trimming and squaring and I think it looks better so I'm not going to trim it.

[JGrout]

the mortises will intersect so if you want to hold true to standards they are as long as they can be as long at the intersection of the two mortises less say 1/16"

You can even miter the tenon ends to get a bit more length

Joe

[KC]

As long as you can would be my answer. And that will depend on where the apron is oriented on the leg and the width of the tenon. You can also offset the tenon to one face of the apron to gain a bit of length. I've seen some people make the mortises meet in the middle and then 45 the ends of the tenons.

[Richard D.]

I wouldn't use tenons at all. Google "Kerf Mount Corner Bracket" which is what I use because eventually you'll want to move the table and be able to remove the legs.

Since this is a woodworking forum I'm sure some feel that anything other than wood and glue connections are abhorrent but if Duncan Phyfe had such things available he probably would have used them.

[John Mihich]

I agree with Richard D. A table that long would be difficult to move around with solid legs and tenons. You can make your own corner brackets. My dinning table I made has wooden corner brackets and they hold well - about 20 years.

[jteneyck]

Most tables I see in furnitures stores have a solid base - the legs do not come off. I'm not saying it's not a good idea, only that it isn't necessary 99% of the time.

John

[jteneyck]

I don't find any reason to make tenons more than 3 or 4 times their thickness. So if you are using 1/2" tenons, they should be 1-1/2" to 2" long. If you set the mortises offcenter, towards the outside of the legs, you could make them 2" long without them intersecting.

I like loose tenons so I would cut mortises in both the legs and ends of the aprons. This approach allows you to cut the aprons to final length and avoid having to fit an integral tenon to the mortise.

I would also use some kind of diagonal between the aprons at each corner.

John

[WaterlooMarc]

Thanks for the help. I wasn't sure if letting them meet was a good idea on a bigger table.

[DogwoodTales]

If I remember this correctly, according to research Chad Stanton had read and relayed to me, a tenon does not need to be longer than 1/3 the width/depth of the workpiece into which it is being mortised.
Any more and there's no real added strength. Any less and there is reduced strength.
So the tenon on a rail joining a 3" wide style, let's say, does not need to be longer than one inch.

With that said, I would also use mechanical fasteners on a table, so it can be broken down.
There's nice and then there's function.

[rwe2156]

Good points about the ability to remove legs. That being said, I've moved a few dining room tables and never took legs off. I think that's mostly for shipping, no?

Length: I would do M/T's and I agree deep as you can. Apron set back will determine maxium length. But I would say 3".

And I would definitely pin them.

Thickness: I tend to keep the tenons as thick as I can with a stubstantial shoulder top and bottom to prevent racking. On a table leave the mortise open to the top of leg.

With 3/4 material I usually go for a 1/8 - 3/16 deep shoulder, which leave a tenon about 1/2" thick. 1" shoulder on the bottom.

Hope this helps