I recently came across some reading from Peter Follansbee in which he discussing the ideas of a square dowel in a round hole. The idea immediately stuck in my head and I decided I should try it. I was in the process of assembling the fauldstools at the time and figured this would be a perfect opportunity to try. If you read my post about the fauldstools you will no doubt have a hard time recalling the square dowels as there is no mention of the experiment. The lack of mention being due primarily to a catastrophic failure.
To start off the failure is entirely on me. I took the idea of the concept and decided to give it a try without reading up on it or trying on a larger scale, thus setting myself up for a disappointing result. To start with I was using mortised and tenoned red oak stool legs that were intended to be assembled via drawboreing for a tight joint. In addition I am using 3/32 holes and 3/32 square stock for the dowels. The hole is bored through the 1/48″ oak side of the mortise, the 1/2″ of the tenon, and the remaining 1/4″ side. All about 1/4″ from the edge.
I ripped a number of square dowels at 3/32, lightly beveled the corners and cut off a piece to try out. First I used a sharp knife to whittle the peg down to a point to allow it to go into the bored holes.
At this point i thought it was looking pretty good. The square edges should look nice and make sure the peg was gripped really tight, the offset taper should serve to draw the two pieces really tight together.
Not so much as it turned out. The dowel started in ok but rapidly proved to be tight and filled the hole while failing to pull the pieces together solidly, I tinkered and finessed it for a few minutes then said to heck with it and whacked it with a mallet. Predictably it didn’t work. As you could see in the first picture the peg wasn’t long enough and the taper was so sharp that instead of drawboring the pieces nicely, the peg was forced off line and slammed into the side of the mortise, ultimately blowing it out.
I believe this failure was a combination of moving parts. First and foremost my impatiens both in not reading enough, and then in not going gently. Second was my material choice, well dried oak may not have been my best chance. Third was my proportions, as close as I was to the edges i was setting myself up for a disaster.
This will get chalked up as a learning experience and be shelved as an experiment for a later date.