Before we actually get into cutting the lap joint itself, let’s talk a little about my tenon jig. This jig is a pretty good addition to any shop. It’s quite easy to make from just a few scraps laying around. For this project you’ll need a tall face, and a board the exact width of your table saw’s fence.
Here are some shots of my jig.
You’ll need a piece of track, a knob and a holding device to act as your securing device.
You can buy the track at Rockler or Woodcraft. Be sure your track will fit into the scrap material you intend to use. My sides are made from 3/4” MDF.
I cut the track by just passing my piece over a single blade enough times to make the track fit snuggly. Since it is MDF I was not worried about ridges as you can clean those up very quickly with a few swipes of some sand paper.
You can see that the “backer” board will get cut through as you make cuts so it’s a board that will need replaced from time to time.
This shot just shows the jig as it fits over the fence. It’s kind of hard to see since the saw’s fence is black.
You want your jig to fit tightly to the fence, but not so tight that you have to push harder than you would push on any other board going through your blade. Not sure that my idea is coming through on this point. But just be sure you have a tiny bit of wiggle room on the jig so that it slides neatly across the fence and is not a bear to move, but not so much wiggle room that as you push the jig it skews a little outward. Get that?
One thing that can help the jig move more smoothly is to use a little wax on the portions that actually touch the saw’s fence. Like anything else – a little wax will do ya. Who said I didn’t have a sense of humor. Ha! :-)
You’ll notice on my jig I do not have a handle or push stick built in. That’s on purpose. My old jig (that fit my old saw) had a handle and I found I did not get a good feel for how the board was moving through the blade. With this jig, I use my hand with my wrist on the saw’s fence and my fingers (and thumb) just on the jig to push it. This gives me a better feel of things and it works better for me. But if you feel better with a handle by all means make one. But be careful where you place the handle. You don’t want it up so high on the jig that when you push you actually bring the back of the jig up off the fence. So experiment as to where the best spot is for the handle.
The set up for this jig is pretty simple. All you really need to set is the height of the blade and the distance from the blade to cut out the waste material.
Now there is one thing I’ve not told you which you’ve probably already thought of. Using the tenon jig means you actually have to make two cuts. One with the board lying flat on the table to get the shoulder cut. The second cut will be upright in the jig.
Now here’s your safety notice. When pushing the board through the blade – keep your pushing hand on the jig. Keep your thumb off the wall of the jig.
What I would do differently if I were to make this jig again would be to add a second track so that I can add an additional hold down.
Okay the next installment will be putting the jig through its paces.
-- "Our past judges our present." JFK - 1962; American Heritage Magazine