Mortising on the Drill Press: Tips and Techniques

When it comes to doing mortises on a drill press, let's talk tooling first. Couple things are real critical here. One is, notice I have a fence on the drill press. We have to have a solid backstop so that we can put our material against it so that as we drill our holes, they're all equidistant from the face. That's really critical.

The next thing is selection of drill bit. Notice that this is a Forstner bit. Forstner bits are really the best way to go for this. And the reason is that, with this style of boring bit, especially compared to a twist bit or a brad point, these allow us to do overlapping holes. And that's critical to the work that we're gonna do here.

We're not drilling a single hole, we're gonna drill a series of holes, and the closer we can get 'em together here on the drill press, the easier the next step is gonna be. So here's what I've done so far. I've located the fence in the right spot so that the distance from the edge of my soon to be mortise to this face is just right. I've also set my depth stop so that it's gonna control the depth of drilling. Next step, start punching holes.

And what I like to do is start by defining the top and the bottom of the mortise. I've got my layout lines. Here's the top of the mortise. Bottom of the mortise. Now, here's where that overlapping business comes into play.

What I would like to do is move this over, keeping it tight against the fence, and get the center point of that Forstner bit right past the edge of that hole, as close as I can to that edge, then drill the next one. Repeat, repeat, repeat, all the way down. That one was perfect. Now, we're not done yet. Next thing we wanna do is get these high spots outta the way.

And we're gonna do that by skinning down through 'em with the circumference of the cutter here. Now, things are much better, but what we've really done is just made the high spots a little bit smaller. So we're just gonna repeat this process. At this point, I'm just gonna plunge, plunge, plunge, plunge, moving pretty fast, just working to get as many high spots outta there as I can. Notice I'm moving, I'm jogging over in really, really tiny increments at this point.

That ain't bad. Next step, we're gonna take this work to the bench. Well, here's the finesse part of what we need to do now, and that's, we need to get the remaining high spots outta here. For the strength of a mortise and tenon, we rely on the sides of the mortise meeting the sides of the tenon. So here's what I'm doing.

I'm running the chisel this way, doing a little slicing action, running it this way. I can feel it kinda bouncing high spot to high spot. So I pull it against those high spots, skin 'em down, pull against the high spots, skin 'em down. Now, one of the things you never wanna do with a chisel is pry. So, good, sharp chisel.

Let the chisel do the work. And just keep working on eliminating those high spots. Now, sequence of events, whether it's drill press or any other tool, you always make the mortise first then go back and make the tenons to fit. In regard to these rounded corners here, my choice is, I leave those rounded, and then on the tenon, I round the outside corners of the tenon as well to match. I find that's way easier to do than trying to get a chisel in here and square these to then match a square tenon I'm gonna make later.

So this one, with that a little bit of work I just did is about done. So it doesn't take much. If you do a good job on the drill press, it doesn't take much to come back here to the bench and clean this up. There. That one's all set.

So this provides a good, effective way to cut mortises using just a Forester bit and a fence on the drill press.