Suggestions on stretchers for work bench

[Matt Evans]

I have been building a small work bench using the old "Well, it oughta work if I do it this way" method of construction, and, unsurprisingly, I seem to have run into some snags.

The bench is made of old pallets, so the wood quality is not the best, but I thought I would try a mortice and tenon joint with a wedge on the outside to draw it tight. Problem is, the wood quality wasn't there, and I have wood failure. I fixed it with dowels, but for my full sized bench out of good hardwood I want to avoid making the same mistakes.

Suggestions on how to accomplish tightening the bench throughout the seasonal temperature and humidity changes? I live in Northwest PA, right next to a big lake, and will be moving back down to VA in a few months, so the climate changes are pretty severe.

Of course, I did this with no drawings, a big mistake, and one that I rarely make, but I can safely say that this project has reminded me why I draw everything out first. (chopping a mortice while waiting for another project to dry, I realized that I had made it about 1/2" larger than the tenon. . .grrrr)


***Forgot to mention, this isn't finished yet. I plan on an edge band around the top, out of walnut, dovetailed at the joints, probably 1"+ thick. Also adding a vise (shopmade), a shelf, and some dog holes. Finish will be natural Watco oil.

In a week or so I should have some CAD files of what this bench is right now, and what I had originally envisioned.

[Brad Wood]

I built a workbench off the top of my head and it is almost the same design you came up with off the top of your head.

For that bottom stretcher, I used a halflap joint.

I'm posting a picture of the bench, even though it is not near the caliber of the benches most of the folks here build (in other words, I'm a newb and this is some of my earliest work). You can see the stretcher pretty well...

edit: thinking of climate change and wood movement, I think this design would probably work out well... the grain is oriented the same on all three pieces that make up the lower leg supports, so the movement should be in the same direction for all of it (vertical in this case)

[Todd Burch]

The tusk tenon design only failed because you didn't leave enough tenon sticking out.

EDIT: I can't tell for certain, but based on how the wood split out, it does not appear that the mortise was beveled on the side that accepts the tusk (wedge). So, instead of the wedge bearing full force on the full mortise face when the bench was racked, it pressed on just the top corner edge of the mortise, and just kept going.

Todd

[Chris Friesen]

I would have not put the upper stretchers right under the top...that would allow me to put clamps under the benchtop if necessary. Putting them lower down wouldn't hurt anything and adds flexibility.

As others have said, the tusk tenon failed because there wasn't enough material sticking out past the mortise in the stretcher. That little wedge applies a lot of force.

[Matt Evans]

The tusk tenon design only failed because you didn't leave enough tenon sticking out.

EDIT: I can't tell for certain, but based on how the wood split out, it does not appear that the mortise was beveled on the side that accepts the tusk (wedge). So, instead of the wedge bearing full force on the full mortise face when the bench was racked, it pressed on just the top corner edge of the mortise, and just kept going.

Todd

You have it precisely. The mortice was not beveled. Hindsight says that that is logical, but the thought never even crossed my mind when I chopped the mortice. First time I have used this joint, and it seems to tighten things up very well, as long as everything holds, so I will probably use it again, hopefully with better results.

I would have not put the upper stretchers right under the top...that would allow me to put clamps under the benchtop if necessary. Putting them lower down wouldn't hurt anything and adds flexibility.

Chris,

I thought about that a little bit. but the bench is small, really small. 20" x 45" roughly. I was worried that stability would be compromised if I shrank the base any. I suppose I could have left top stretchers down a few inches and morticed the legs into the top. . . Not a bad idea for the bigger bench I am planning.

Brad,

Looks like it is functional! How did you attach the top? Lags through the top stretchers? Thats what I did for mine, but for the big one I am thinking that chopping a mortice into the top and having the bench be, in effect, the top stretcher would be quite effective.


I am wondering whether I could modify the European bolt stretcher concept to incorporate a tusk tenon in the center, as opposed to the bolt? Any thoughts on that idea?


I used the bench as a holding platform for a glue up today, and am I ever happy about having another surface in the shop! Now to make the vice and dogs, drill dog holes, add the edge, finish it. . .

[Cliff Rohrabacher]

I think the amount of force you should use to set the tusks in place is minimal.