I am thinking about building the Lon Schleining workbench . The base has double wedged tenons. The tenons are cut at 5 degrees to accept the 5 degree wedge. How does this spread the tenon? The articles on wedged tenons say to remove 2.5 degrees from each side of the mortise and cut a saw curf about 1/4 inch in from the edge. This is not how it appears on the scaled drawings. I would appreciate any/all advice on the technique for the wedged tenons used in building this bench. Are wedges and corresponding tenons cuts cut on a band saw? Thanks for the help.
JAB1
Replies
Wedged Tenons
Didn't see the plan. I would File a bit off the tip of the wedge . It's still at 5 degrees, but it will drive deeper into the tenon before bottoming out.
I just completed this bench last fall, quite a project, but very sound and heavy. Built mine out of white ash (less $$$) and used walnut dowels and wedges - nice contrast.
As for the wedges; I too was confused until I figured it's impossible to expand a joint by simply filling a wedge shaped void with a similar shaped wedge. So I ignored the drawing and simply cut a straight curf on the tenon with the band saw about 3/32 wide and drilled a 3/16 hole at the end of the cut. ( I also cut the wedges on the band saw)
This allowed some room to start the wedge and a hole to relieve some stress.
Glue it up and tap the wedge in as far as it will go.
Good luck with the bench, I think you'll like the finished product.
I'd be glad to share any more info if you need it. Just post a question.
Mark
The attached picture is from the book by Schleining. The way I interpret the sketch is that the 2 slots are simply parallel sided slots.
On the other hand the author states:
Permanent wedges are usually glued in place during assembly. They fit into wedged-shaped
slots cut into the end of the tenon and are trimmed flush with the leg once the glue dries.
The real benefit of this joint is the mechanical strength of the connection. It ensures a very
tight fit between the tenon and the mortise, since the wedge expands the end of the tenon,
effectively locking it in the mortise.
I think that what is happening is that the wedges are wider than the slots so that they will in fact expand the tenon. On the other hand the author is is not suggesting that you flare the mortise because of the sheer size of these joints. The book seems to be targeted towards relative beginners who would probably end up with a less than perfect joint where the tenon would not contact the mortise along its full length.
I avoided this problem by using the bench bolt method described in the book to attach the stretchers so that the bench is in fact dismantleable (?). This worked well. I made my own8" bolts by welding nuts to 12mm threaded rods. For the first year the bolts needed retightning every 3 months or so - about 1/4 turn at most but it makes a big difference.
I hope this helps.
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