Timber Framers Guild

Japanese Tie Beam to Plate Joinery

Posted By: timberwrestler

Japanese Tie Beam to Plate Joinery - 02/01/10 04:14 PM

I've been wondering what the most effective joint for joining round tie beams to the plate would be. I'm guessing a cog of some kind. It seems like a dovetail would be putting a lot of dependence on a very small amount of wood. I could drop the ties into the posts, but I would rather not. There's a few options shown in Engel's book.

Thanks,
Brad
Posted By: Chris Hall

Re: Japanese Tie Beam to Plate Joinery - 02/01/10 08:20 PM

Hi Brad,

thanks for posting up the question. The three versions shown in Engel's book comprise the standard choices. As Engel and many others have noted, the housed dovetail is a weak option. If one goes with the housed dovetail then a reinforcing tie bolt is required to tie the beam horizontally to the plate.

The cogged lap joint is the best option, if you're looking for structural effectiveness. There are a couple of different versions besides the one shown in Engel's book, however what he does show is fine. Engel does however mis-name the cogged lap joint illustrated - it is not, as he calls it, a variation on kyōro gake, it has its own name and is called tsuki-watari ago

~Chris
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