To clamp or not to clamp

Sep 25, 2006 5 Replies

I was wondering about this today while clamping up some MDF boxes...



Does anyone have any experience that clamping a joint while the glue dries results in a stronger joint than not clamping. (Assuming the parts fit fairly well and don't need clamping to bring them into alignment.) I think I've always assumed that a clamped joint would have more wood fibers in contact and produce a stronger joint.



Mike



I think your responses are going to very greatly depending on the joint in question. Miter joint with no clamps? Forget about it! Through dovetail joint with no clamps, sure probably ok. M&T joint, forget about it! unless it is a really tight M&T. Half lap-joint? Forget about it!

Stoutman

Clamps are only used to hold the joint together and keep the pieces aligned while the glue dries. Masking tape is often used as a clamp. Stronger clamps aid in making ill fir pieces, fit together.

In _Understanding Wood_, Hoadley acknowledges that a "rubbed joint" and be just as strong as a clamped one, but points out that few joints are that perfect. He recommends clamping pressure of 100-250 psi on domestic (US) species. That adds up to lots of clamps on a big joint!

In a perfect world, I would have to vote for no clamp as long as the joint fits tightly... The reason being, I think that most of us probably use too much clamp pressure than is needed for a good BOND and squeeze out too much glue. Using a brad to tack two pieces together, or using tape or similar band clamps on tight fitting and mating pieces will not force out all the glue needed for bonding.

Just my two cents...

Dennis

Dennis Slabaugh, Hobbyist Woodworker

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