After a wonderful morning fishing with Braedan, I got down to joinery on the lensboards. But let me back up a little.
The lensboards (four of ’em) started out as a single 4/4 piece of poplar that’s been sitting in the scrap pile for years.
I’d already made a pattern out of 1/8″ veneer stock, so I measured up the board and figured there was enough material for four three-piece boards, with 3/4″ wide breadboard ends. Poplar’s a good wood for this, not too heavy, easy to mill, and takes a finish well. Also, one of my lenses will be threading into the wood directly; poplar is just right for that.
I planed the wood down to about 3/8″ and cut the pieces. Four center boards, and two long strips for the ends:
Time for joinery. I don’t get hung up on dimensions here; I default to somewhere around 1/4″ long for the tenon, and I just run a groove down the centers of the long strips. I set the blade height, adjust the fence on the tablesaw, and run the groove. Turn it around, lay the opposite face against the fence, and run the groove again. You end up with a perfectly centered groove this way:
The tenons are cut on a horizontal router table with a two-flute straight bit. I like the horizontal table for this, because you keep the faces flat to the table when you cut, making for a more stable, better controlled cut. I set the bit height for something less than the should depth required, test cut on a scrap of planed wood, then ease the cutter up slightly over and over until the tenon just fits the groove.
Some glue on the tenons, and here’s the assembly clamped up:
A few hours in the clamps (though only about 45 minutes is necessary), and I’ll cut the individual boards apart, size them, and layout the rabbets in the back.