In my small chest build, I started working on the bottom. This is usually done with a series of tongue-and-groove or shiplap joints. I prefer tongue-and-groove, but although I do have a set of match planes (and a Stanley 45), they are for 1/4″ grooves, and I’m working with stock where 3/16″ would be more appropriate.
Match planes are great for pumping out a lot of tongue-and-groove joints. To do it at almost the same speed, I could spend $30 on the Veritas tongue-cutter for my plow plane in that size. But none of this is necessary, and I didn’t feel like waiting around for that cutter to arrive anyway. So I set out to do it with the plow plane. Doing so requires three cuts instead of the two that you’d need to do with match planes; the tongue is nothing other than two rabbets.
You start by plowing the groove side, which is the same no matter what:
It’s best to plow all of the grooves at the same time, so that you don’t have to constantly readjust your plane.
Then, with the groove side still up, adjust the fence so that the cutter sits right on top of the “outer” side of the groove (the side opposite the fence), with the sides of the blade and groove flush:
This is where I have to say that I really like the Veritas small plow. I could do this with my Stanley #45, but moving and locking down the fence on that thing is finicky and difficult to do with precision.
Now, flip to your tongue side of a board, and (here’s the important part) clamp a scrap to the side that you’re going to cut, flush to the top. Then cut this side of the tongue:
The reason for the scrap is so that your depth stop (which is usually on the side opposite the fence) has something to hit when the cut is complete. Yes, I made the mistake of forgetting to do this on my first attempt.
Again, it’s best to cut all of your boards at the same time. Then, put a board’s groove side up again, and set the fence so that the cutter rests on the “inner” side, like you did before:
This one is more difficult to see, so feel free to use any optical method of cheating that comes to mind.
Then flip back to the tongue side, and cut this second rabbet that makes the tongue:
You probably won’t need to include the scrap this time, because the depth stop should register against the tongue itself.
It’s possible that you might feel that the fit is too tight when you’re done. In that case, just adjust the “inner” side with a rabbet plane. I’m using my miniature shoulder plane because I recently said that I seldom use it, and I feel guilty for that. Or something.
If you’ve got a lot of these to make, one possible time-saver is to reset the fence to the trimmed side after you adjust the first tongue.
That’s more or less it. And I now have everything ready for the bottom of my small chest:
without a rebate plane, I have used my plough plane to make small rebates.
On floor boards, the tongue and groove are not centered so one can sand/plane the floor (with the “thick ” side above). So it is important how one flip the board.
Interestingly, it might be interesting in some situations to make either tongue or groove on the two sides of a board. see the video:
As the board coming from a tree are slightly tapered, by alternating double tongued ones and double grooved ones you don’t need to have the two edges of each board perfectly parallel. Reducing waste wood.
Regarding the centering of the groove, this is among a bunch of “subtle” details that I didn’t include in this post because I thought that they were kind of obvious. Perhaps I should make a video about this some day.