Should a mortise/tenon joint be tight in winter and loose in summer or vise versa? I use oak and walnut most of the time if that matters.
Is it a good thing to have a rough surface on the tenon so glue can be trapped, or is it better to make it smooth and use less glue? I’m cutting tenons with a radial arm saw and a 80 tooth finishing blade that leaves a wavy (bottom) cut.
-Ken
Replies
No, the tenon should be relatively stable all year round. Both pieces of wood will expand and contract together, although not necessarily at the same rate. Now, if you are talking a wedged tenon like in a trestle table, then the wedge might loosen in the winter, but I doubt this is what you're talking 'bout.
As far as the smoothness issue goes, the best joint is two smooth surfaces with very little glue that meet up perfectly. With mortices, the walls tend to be a little jagged and imperfect, and the fit is never perfect (at least with hand tools). So, given that one surface is likely a bit rough, I'm not certain a smooth tenon gives much benefit. I've never experienced difficulty with a tenon that wasn't perfect. Just to give you an idea, I consider sanding with 80 grit *rough*.
The wavy cut you are describing sounds like a shoulder cut (?) With this cut, it is important to have the shoulder meet the mortised pieces surface for looks as well as mechanical advantage, but this isn't a glue surface.
Tom
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