Hand Tools Archive

Re: Fully Mated

Hank Knight
Clint said, "I have found consistently over the years that a fully mated dry fit joint will not fail."

If the joint is fully mated along its length, it will almost certainly be successful, whether it is sprung or not and regardless of the kind of glue used (assuming an acceptable wood glue). I dry check joints by stacking one mating edge on top of the other and checking to see that the top board sits solidly on the bottom one, with no rocking or spinning and there is no light visible through the mated seam. This is not as easy to achieve as one might think, especially for an impatient person. It usually takes me a number of passes with my jointer plane to get a satisfactory dry fit, and I find that it is really difficult to test a sprung joint to see if it is fully mated in the center. Consequently, I shoot for a flat, straight joint that is fully mated along its length with no pressure, slight or otherwise, required to force it together. I have never had a joint fail when it was prepared in this manner. I understand the rationale behind sprung joints; but, like Clint, I do not believe springing the joint adds anything if the wood is dry and properly prepared as I described above. In fact, for me, springing the joint adds to the difficulty of preparing the mating surfaces.

My $.02.


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