breadboard attempt, pics, help

[John Grossi]

I am trying to make a rolling cabinet for my wife. The top will be piano hinged in the back. She can keep the top open, giving her access to her art supplies. When painting she will roll it up to her work station. When not painting, the idea is to roll it next to a couch, looking like a piece of furniture. She is thrilled with it so far, until I started making the top. Four maple boards glued up went very well. The breadboard idea has not gone well. I used 3 floating tenons, glueing them in the mortised top. I then attached the breadboards, using cawls to keep it straight, and clamped long ways to keep it square to the top. I then drilled the dowel holes on my drill press. It looked good up to this point. I took off the breadboards, and glued the middle tenon and the two dowels in that middle tenon. That is the only glue I used. I checked the next day and they have a slight flex. I know it is supposed to be able to move but this has me very disappointed. I am ready to go get a sheet of maple plywood and make the top out of that. Any help would be appreciated. Thanks John

[Dave Cohen]

I checked the next day and they have a slight flex.

What has the flex? The glued up top or the breadboard end, or both or something else?

[glenn bradley]

I think maybe the pics are not clear to us. Another shot with you pointing a finger maybe? If the breadboard ends are not staying in position relative to the surface of the glued up panel I would think your mortise/tenon fit is too loose(?).

[Narayan Nayar]

OK, we have to piece together what's going on from your words; the pics, as Glen pointed out, aren't clear enough. So bear with us.

I'm going to take a few wild guesses here:

We don't know how wide or long the floating tenons are. Their width and protrusion will have a lot to do with how stable the breadboard end is in relation to the top. In other words, "3 tenons" might provide you with a total of 2" of tenon or it might provide you with 18".
I've done two breadboard ends and both of them had what I think is called a stub tenon--a long but short tenon which helps keep the breadboard end registered, from which the longer tenons extend into the breadboard end. If you were to look at the mating surface for one of the breadboard ends I'm talking about, it would look like a long dado with several mortises in it. You wouldn't by any chance have used one of these, would you?

[Jim Kountz]

Did you use the draw bore method when drilling for your dowels? If you're not familiar with this, you drill the holes in the breadboard end then transfer those marks to the top. But dont drill right on the mark, instead move over a tiny fraction and drill. Then when you drive the dowels in it will draw the joint up really tight. This sounds kind of confusing but its really quite easy and to me a must do thing for breadboard ends since they are only glued in the middle or at one end.

[John Grossi]

Guys, thanks for your replies. I put up a few more pics. Not sure they are any better. Dave, the top is fine, the flex is in the breadboard. I can stand on the side, grab the breadboard and feel a slight flex. Glenn, the fit seemed fine when I dry fit, before I glued and doweled. Only a few thousands difference between the mortise slot and the tenons. Narayan, the dimensions are as follows. breadboard, .750 X 2.250 X 24". The tenons (3) are .310 X 3" X 2.50". 1.50 of the tenon goes into the mortise. Perhaps this is the problem. Should have I cut the mortise deeper, and made the tenon longer? I wish I knew of that doweling technique. I had everything squared up and clamped while I drilled the dowel holes on my drill press. John

[Matt Zettl]

John,

I've done many breadboard ends, and I think that this is one instance where a slip tenon is not the best option. It introduces an additional source of error, that being the fit of the slip tenon in the top itself.

I think that the best way to do this is to cut a continuous tongue-tenon in the top, and a matching groove-mortise in the breadboard end. This technique has been described in detail in FWW by Christian Becksvoort and others over the years. Although it is more difficult to do, and requires some fiddling to get the fit correct, it is very effective. I have never had one of these types fail.

The breadboard end can be fixed to the the main body of the top via dowels inserted perpendicularly through the tenons, or by screws inserted into the tenons from the end of the breadboard. I've done it both ways, and each has advantages and disadvantages. Functionally, I don't know if one method is superior, and the choice may be largely an aesthetic one.

I am currently working on a top for a dining table that is almost 4' wide with breadboard ends. I have been photographing the process as I go in hopes of posting the technique when I am done. That may be a little late for your project though.

I hope I have been of some help.

Matt

[Carl Babel]

I've had good luck with the Draw Bore method that Jim mentioned - it does snug the joint up nice and tight.

Another option (although it may be way too late for this project) is to use the Greene & Greene style breadboard ends, something like this: http://www.ptwoodschool.com/GreeneAndGreeneDetails1.html

[Roger Barlow]

I've had good luck with the Draw Bore method that Jim mentioned - it does snug the joint up nice and tight.

Another option (although it may be way too late for this project) is to use the Greene & Greene style breadboard ends, something like this: http://www.ptwoodschool.com/GreeneAndGreeneDetails1.html


Thanks for that link, nice resource, never saw it before.