Breadboard question...

[peter slamp]

I've read where you can use stopped mortises so that the tenon is hidden for breadboard joinery. Wouldn't this restrict the cross grain movement of the table? I'm sure I'm missing something. Can someone help me understand how this is possible. Sorry if this a stupid question. Noob here. Thanks, Peter

[Andrew Shaber]

The tennon doesn't contact on the long dimension. The tennon should only be connected in the middle (or one end) and be connected with a floating connector elsewhere

[peter slamp]

I understand that part. Won't the stopped groove itself restrict seasonal movement, if it is closed at the ends?

[Jesse Thornton]

I'm not sure how you picture the movement being restricted. I've done breadboard ends as described, (glued middle tenon, pinned end tenons with elongated slots), and the top has contracted and expanded a good 3/8" with no problem. Can you describe more specifically where you imagine things getting hung up?

[Jim DeLaney]

I understand that part. Won't the stopped groove itself restrict seasonal movement, if it is closed at the ends?

Peter,
The tenon doesn't go all the way to the ends of the mortise. A quarter inch gap on each end is typically more than enough to compensate for the expansion.

[peter slamp]

I think this answers my question. I think I was thinking a long stopped goove and a long 'tongue'. Kinda like a real long tenon and mortise. I guess the proper way to do it is with multiple shorter tenons (what length?) In this case you only actually glue the middle tenon snugly. The rest of the tenons are pinned loosely. Am I visualizing this correctly? The one glued tenon will hold the breadboard on securely? Thanks.

[Jesse Thornton]

Since the breadboard end is only glued in the middle tenon, in order to keep it tight all the way along, I hand planed a very slight concave arc on the edge that meets the table so that when the middle is pushed in tight and glued on, the spring like tension of the rest of the breadboard keeps it tight to the table (in addition to the dowels). Much like a bowed clamping caul works, but in reverse. I'm not sure what the best method is for drawing a consistent arc on the board is; I used a long string tied to a nail on one end and a pencil on the other (I can't remember how long) to give me the radius i wanted - I think the curve on the board went in about 1/8" in the middle of a 42" board. Again, I don't know what the best radius is either, but it seemed to work well.
Here's a pic of a breadboard mortise and tenon, pre glue up and before I cut the elongated dowel slots:
http://picasaweb.google.com/jessedav...21525679996946
I could have made the tenons a bit longer, but it's held up well so far.

[peter slamp]

Nice to see that for visualization purposes. Thanks!

Oh, by the way, how did you cut those mortise and tenons?

[Dennis Peacock]

Peter,

I show how I did my breadboard ends here on my personal web site.