Is clamping entirely necessary?

[Jim Becker]

Looks like you could flip one side end-for-end and clamp them both with a couple bar clamps.

Ding...ding....ding....! Excellent idea! It will need support on the open ends, however to keep the clamping from pulling them askew. But that would be simple to cut from scraps since he'll know the angles.

[Steve Rozmiarek]

I always thought the point of clamping was to encourage a thinner glue line, which is stronger for titebond glues. Maybe I'm wrong, but it hasn't failed me, so maybe it's right.

[glenn bradley]

Draw bore, surgical tubing, wedges, pocket holes, etc. All of these are a form of clamping the joint. Applying a PVA glue and simply setting the assembly on a flat surface will not provide the strength of a clamped joint. Different glues change shape and volume as they set depending on formulation. Placing them under pressure assures the mating parts are stable as the adhesive changes. Visit some wood glue manufacturer's sites and see if any of them advise NOT using clamps. There are all sorts of things that people do or have done over the years. I'm an ex-geek and so tend to follow the manufacturer's advice since they make the product .

From Franklin, for example:

Clamping

A variety of clamps and clamping systems are available for assembly joints. Enough clamping pressure is recommended to provide a thin glue line along the entire surface of the joint. Direct contact of the gluing surfaces is required to obtain maximum strength.

[Robert Hazelwood]

When we are talking about glueing mortise and tenon joints, the clamps are usually just to ensure that the shoulder is well seated. The actual glue joint is between the tenon cheeks and mortise walls, and the clamps aren't affecting that. If the fit is snug enough then I think you could seat it with mallet taps or something, and then just avoid disturbing it until the glue sets, and I don't think the joint would be any weaker. But I would still find a way to clamp it if I could, just to make extra sure the shoulder is perfectly seated.

[Richard Coers]

When we are talking about glueing mortise and tenon joints, the clamps are usually just to ensure that the shoulder is well seated. The actual glue joint is between the tenon cheeks and mortise walls, and the clamps aren't affecting that. If the fit is snug enough then I think you could seat it with mallet taps or something, and then just avoid disturbing it until the glue sets, and I don't think the joint would be any weaker. But I would still find a way to clamp it if I could, just to make extra sure the shoulder is perfectly seated.

Well seated and to prevent any hydraulicing that could let the tenon slide back out a bit if air is trapped inside the joint.

[Ross Manning]

You don't need clamps for the joints in question if the concern is strength of joint. The members are butted end grain to long grain, and no amount of clamping will make this a strong glue joint. As stated above, the strength of your joint comes from the long grain to long grain of the mortice and tenon, and this is unaffected by any clamps. All clamps would do for you is help ensure the gaps are closed (still important) but if you can achieve that to your satisfaction via other methods, you can avoid using clamps.

[Jay Michaels]

Excellent input -- all of it -- thank you.

clamps.jpg

I took up Bradley on his recommendation for flipping one end-for-end and butting it against the other to make the clamp-up easy with some scraps to line everything up. That has the added bonus of making it much easier to square them up too; not just hold them tight. I then used a couple of off-cuts to aid clamping on the short ends (those off-cuts are not glued/taped/cemented in place; they don't need to be since they are trapped by the straightedges clamped to the sides).

Thanks again.