Reply To: Joining Three Pieces for a Mud Room Bench
Welcome! / Forums / General Woodworking Discussions / Projects / Joining Three Pieces for a Mud Room Bench / Reply To: Joining Three Pieces for a Mud Room Bench
The gaps appear even with modest clamping pressure. Interesting idea about the dowels. Haven’t thought of that approach and may add an interesting design feature. Would you assemble the three pieces first with glue and then drill the holes for the dowels? What spacing for dowels would you use? I was going to use dowels for the purpose of alignment of the pieces (4 corners)
If the gaps can’t be closed with modest hand pressure, then I’d say you’re not done. You’ll need to better mate those surfaces…probably time to crack out the jointer or other plane.
After you joint the mating surfaces so the gaps will close under modest pressure, use your alignment dowels during the glue up, get the glue-up done right. The alignment dowels should prevent shifting as you drill the holes for the structural support dowels, but if you feel they might not, then just let the glue cure, and you’ll be sure nothing will move.
Remember, dowels in this sense are nothing but loose tenons which happen to be through tenons. Judging the spacing and size of tenons might have some science, but I’m unaware of it if it does exist…any mechanical engineers want to weigh in on this? In the absence of hard science on the size and spacing of tenons, do the best you can. You want the tenon to be as hefty as reasonably possible given the requirements (must support humans, so there are safety concerns) but you cannot leave the walls of the component that will be mortised too thin, either. White oak is good and strong, and assuming your components are of quality stock I’d want a quarter inch on each side of the mortise hole, and more if I could get it. As for the dowel/tenon, I’d want an inch in diameter if I could get it, but I’d settle for half that. If the components are too thin to permit sufficiently beefy mortise walls and tenon/dowel thickness, then you might have to resort to metal…i.e. screws / bolts. Can’t easily beat the strength of steel.
Looks as though your current design has 4 natural points for the dowel/tenons connecting A to B and B to C, so 8 dowel/tenons in total. The horizontal “B” rails would be my target, since that’s apparently the beefiest part of the middle component, and the vertical rails in the A and C components which abut the B rails appear to be the strongest parts of the A and C components, too.