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jig

Incra Box Joint Jig Review

incraboxjointjigBox joints (sometimes called finger joints) are a handy and strong way to join two pieces of wood at a 90 degree angle. I’ve tried a couple times in the past to build my own box joint jig. It’s supposed to be easy but I could never get it to come out right. Finally I decided that I have more fun building stuff than building stuff to make stuff so I shelled out the money for the Incra Box Joint Jig.

It’s not something that is required to do the job, but it helps me get the job done faster and with nearly perfect results every time. It’s hard to screw this thing up, but plan to spend 30-60 minutes with the DVD to set it up out of the box. Now that I’ve got it all calibrated, I can whip out box joints of any size in just a few minutes. The design of the jig is also a little safer than a normal crosscut sled would be.

The only gotcha that I didn’t think of ahead of time is the size of my dado stack. Since I have a somewhat wimpy table saw, I opted for the smaller 6″ dado stack. Why make the motor spin all that extra metal around? That choice combined with this jig means that I can’t cut box joints into wood that is more than 1/2″ thick because the blade doesn’t come high enough out of the table. The 8″ dado stack would solve this problem, but truthfully I doubt it will bother me very often.

I’ll have some pictures of my first real box joint project in a post coming soon. For now, here’s a picture of my very first test. Obviously the fingers haven’t been trimmed down but you can see how nicely they fit together.

boxjointsample

Cutting Plywood

circularsawtrackI usually work alone in the garage so cutting big sheets of plywood or MDF can be a hassle. Running it across the table saw just isn’t an option until I’m dealing with smaller pieces. In the past, I’ve picked out a straight 2×4, clamped it to the plywood, and then used that as a guide for the circular saw. That works pretty well but it can take a long time to get the guide set up in just the right spot.

I finally got around to making a jig to help with this. It’s not complicated and I definitely didn’t invent the idea, but here’s how you make it:
1) Cut off a 3″ by 8 foot slice of your sheet of plywood. Make sure that you’re keeping a factory edge and you mark it. That’s your straight edge.
2) Measure the distance between your circular saw edge and the blade. Add 3″ for your cutoff and then another ~3″ for clamp room. Cut off another slice that wide. That will be the base of your jig.
3) Glue the 3″ strip on top of your base strip. Make sure the factory edge is pointing at the wider side of the base strip. It should be about 2″ from one edge. Add nails to hold it in place while the glue dries.
4) Now make a cut with your circular saw to trim off the extra wood.

You now have a zero-clearance jig to help you rip plywood. If you’re making a cut on the plywood, add a pencial mark on each end of the sheet where you want to cut. Then clamp your jig down so that it is right up against your pencil marks. Run your circular saw, holding it tightly up against the top fence and you’ll get nice straight cut in the right spot.

My typed-out description isn’t great, but there are lots of videos showing how it all works. I recommend Jay Bates’s blog post and video. He gets to it about halfway through the post/video.

The 8 foot length is a bit long when you’re doing 4′ cuts but we’ll see how it goes. Maybe I’ll end up making a second shorter one.