I’ve been reading Tage Frid Teaches Woodworking:Book 3-furniture making. It has a trestle table in it showing a post/upright wedge tenoned ( both sides) to the foot/base. This construction is similar to a finewoodworking trestle table shown in the archives as well.
The upright tennon is about 10″ wide and wedged both sides with 1/4″ x 2″ long wedges ( I am not talking about the strecher that is loose wedged the upright ) My question in this joint does not seem to allow for wood movement. What happens when that joint shrinks. If you have Tage book handy, he alows for wood movement in the top top of the botled upright/leg to the tables apron assembly and its only 9 1/2″ wide ( x 1 3/4″ thick ), but this wedged tennon does not seem to allow for movement.
Tage Frid does not mention how he glues this joint other than it is wedged at assembly on both sides. I just can’t see how the wedges hold the tenon in the motise when the wood shrinks.
Any explanations out there?
Thanks
Jason Guest
Replies
Should the wood shrink, the tenon can be tapped in further for a good fit.
I just looked at Frid's book. You're right, that use of wedges seems to be asking for trouble. If the post shrinks across that 10" width, it gets loose in the mortise. Me, I'd just glue the tenon in the middle 4-5". The glue would have a nice big area, and would be in shear. If you don't trust glue completely, you could cross-pin the joint -- again nearer the middle than the extreme ends.
Er Jamie, not quite....You may notice the stub tenons/haunches? These take up a substantial portion of the width of the upright. Wood shrinks from the edges inwards. The wedged part is well in, chances are that this part would not shrink enough to cause trouble, especially if well glued and the end grain sealed- think hysteresis.
Also, he has drawn the grain there of quarter sawn stock- this would minimise shrinkage across that width.
Anyway, ah have come ter beeleeive that you guys are plumb paranoid about wood movement ahead of choice of suitable timbers and methods of construction whilst paying attention to climatic conditions at the time of construction (well the thought just crossed my mind) (;)Philip Marcou
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