All,
I’m hoping there is some kind of rule of thumb…
I’m making a small pedestal table for a lap top computer. The base (2″ square) will have four legs joined to the center column with mortise and tenons. The tenons are 3/8″ thick, 7/8″ long and 1 3/8″ wide.
My thought is to use 1/4″ dowel and drawbore the pin to provide a bit more strength and facilitate the glue up process. Part of my concern is that the 1/4″ of stock that I thought would be between the opposing tenons got eliminated when chopping out the adjacent mortises…so none of the tenons have a seat/base to support them.
At this point I’m inclined to center the 1/4″ hole on the tenon and keep the offset modest, like maybe 1/32″ so that the stress is not too great and causes tearout on the tenon. Any thoughts?
Replies
The tenons are 3/8" thick so the shoulder formed by the leg and tenon is all the "seat" you need. Good idea to draw peg the tenon, make sure the opposing pegs are at different heights, otherwise they would have to be stopped short . Point the dowels with a pencil sharpener or knife .The offset should be minimal,1/32" is plenty.
If you make the offset too much it will tend to splinter out the other side. If the hole is off center too much, clamp a scrap over the hole before pounding in the peg. Remove scrap and cut flush.I mentioned this because it is easy to over drill the offset.I use transfer punches now instead of the bit I bored with, gives a better mark.
mike
Mike,
Thanks for the ideas, I've got a pencil sharpener and the piece of scrap is great. How far in on the mortise shoulder would you go drilling the pin hole? For instance, if i drill 1/4" in on the mortise shoulder...that means 1/4" for the dowel and 3/8" left on the tenon behind the the pin hole, is that enough material behind the pin hole such that the hole in the tenon won't rip out? thanks
You have a thick tenon so you will be fine . Strive for 1/32" and no more for the offset.This is enough to pull the joint up, bending your peg a bit but not enough to damage the tenon.
mike
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