08-21-2016, 06:55 PM
(This post was last modified: 08-21-2016, 06:58 PM by Edwin Hackleman.)
I applaud Page 23 of Woodsmith #226 for showing a method of cutting a through slot with a Forstner bit using multiple passes of course. They then recommend using a chisel to smooth out the sides of the slot. The chisel works, but it's tough to really get the sides smooth, especially when working with really hard wood. Your chisel's edge is usually going across the grain most of the time.
Lacking a mortising bit, I elected to try another technique on a 4" long slot that I needed. I used a fence and dropped the bit to the far right of the rough-drilled slot, lowering it about 1/4" down into the slot. Then I slid it all the the way around, right to left and then to left to right on the other side of the slot, cutting with the bit's lifters while moving the workpiece. You may get by with only a right-to-left pass. Then I stopped the motor, dropped the bit down another 1/4" and repeated until the sides of the whole groove were smooth. To drop the bit down, I raised the DP's table, being careful not to swivel the table.
The rough sides will then be "routed" much smoother. This method also works to enlarge the slot a tad. Just nudge the fence back a little. You'll get the hang of it once you give it try.
Lacking a mortising bit, I elected to try another technique on a 4" long slot that I needed. I used a fence and dropped the bit to the far right of the rough-drilled slot, lowering it about 1/4" down into the slot. Then I slid it all the the way around, right to left and then to left to right on the other side of the slot, cutting with the bit's lifters while moving the workpiece. You may get by with only a right-to-left pass. Then I stopped the motor, dropped the bit down another 1/4" and repeated until the sides of the whole groove were smooth. To drop the bit down, I raised the DP's table, being careful not to swivel the table.
The rough sides will then be "routed" much smoother. This method also works to enlarge the slot a tad. Just nudge the fence back a little. You'll get the hang of it once you give it try.
Rip to width. Plane to thickness. Cut to length. Join.