How to Make a Tongue and Groove Joint by Hand

The important issue about which side to reference the T&G fence on skirts around the critical issue a bit. If the stock is planed before cutting the joint (as it is), the boards comprising the panel may not all be the same thickness. If you reference the plane fence off a common side, then that face of the panel is always going to be flush when assembled, and the error in thickness is pushed to the opposite face. So you want your show face to be the one that the T&G fences rested against. However, stepping back to how one chooses the orientation of the boards comprising the panel leaves out a critical step. Think about how these planes work. The tongue orientation (or plane) cuts two shoulders (one on each side) that you can see for the rest of your life. So you want to plane with the grain for this operation, no tearout. The groove orientation (or plane) cuts a groove down into the stock, the bottom of which you will never see again. So you do not care which direction you plane to cut this portion of the joint. Planes invariably rest against the left face of the board when you plane. The tongue cut must be with the grain running up and out as you view along the length of the stock. The other edge of the board is by definition a groove cut and you do not worry about the grain orientation there. So I lay out the boards for appearance as much as possible, but focus on the grain direction as the final say-so. Another thing to think about, but which is a fun thing to do, is to bead the T&G joint. The bead disguises the gap
and adds a decorative element, makes the inside face more interesting. The L-N planes are machined to work on stock that is either exactly 1/2″ or 3/4″ thick. Wooden paired match planes can be found in any size you can think of. However the Stanley series of T&G planes (swing arm or come and go) are 3/8″, 5/8″ or 7/8″. This means that the T&G is centered on those stock sizes, but shifted off center for other sizes. Here is where making sure that you reference off a common face is critical. For beading, you want to bead the shoulder of the tongue board that has the widest face so that you can plough the bead to full depth. Ironically, because of the mechanics of planing, the grain direction is opposite for the beading step. So you have to make a choice about where you want to risk tearout–with the tongue shoulders or with the beading. This is one reason why come and go beading planes were developed, to deal with grain reversal. Scratch stock for beasing also eliminates this problem as you can scratch in either direction.