Using my Stanley #45 plane to cut tongue and groove.
For the purpose of this example I am using a couple pieces of pine.
I am using the 1/4” Tongue and Groove irons, and have the depth on the tongue iron set as deep as it can go. The Groove depth stop is set to match this depth once the tongue has been cut.
The #45 is set up with the short rods as opposed to the long rods. There is nothing stopping a person from using the long rods, I just prefer to use the short ones when I can.
The knickers are not required, nor recommended for working along the grain.
When cutting the tongue, the fence is installed in the upper holes, to lower the fence below the cutting iron. It can be moved back up to the lower holes to raise it back up for plowing the groove.
I finish up with a little chamfer on the edge of both boards, to have a little V-groove. This is helpful to hide the joint between boards, especially if there’s any gaps from expansion and contraction of the boards.