Workshop Tip: Perfect Through-Tenons Every Time
A reader's technique for making through-tenons that fit without a lot of paring.
Through-tenons are tricky, no matter how you cut them, because the ends are visible and any gaps are sure to show. If I mill them to final thickness right away, I get obvious scratches from the outer blades of my dado set. When I leave the tenons thick, they take a while to pare down with a shoulder plane or rabbet plane, and it’s easy to make a mistake.
So instead, after cutting all of the mortises, I mill one full tenon on a test piece, dry-fitting it in a mortise to perfect the fit. Next, without changing the dado-blade height, I mill the actual through-tenons, except the section at the end that will protrude from the mortise. Then I lower the height of the dado stack slightly and finish the job, leaving the ends just a hair thick.
After that, it’s simple to bring the ends down to final thickness with a handplane. There isn’t much wood to remove, and the adjacent surface acts as a guide. You get perfect through-tenons every time, with no gaps or tool marks at the tip.
—ARTHUR TURLAND, Kincardine, Ont., Canada
Illustrations by Dan Thornton
From Fine Woodworking issue #280