So, if you happened to read my post last month on injuring myself, you’ll recall I did so because I was hoping to make a box joint jig. A box joint, or as it also known: a finger joint, is a series of overlapping “fingers” along a joint. This style of joinery gives lots of glue surface area as well as shear strength to a corner joint. It’s commonly used for the corners of a box, thus the name.
Well, I did manage to make a first attempt at a jig and made a single joint test. I was hoping to use my standard table saw blade with my sled in lieu of purchasing a dado stack1. The jig is a bit too loose in the cuts and it’s possible my table saw sled is a bit too loose in the miter slots, as well. This combined with some cheaper birch plywood (there are lots of voids and a very thin veneer) resulted in the fingers looking more like a boxer who’d just fought Mike Tyson.
Also, the depth of the cuts were a bit too deep (which is easy to adjust, at least). But gluing up the loose joints was a mess.
I had sort of given up on the experiment as a failure, but I did recently go back and sand the fingers down; this time on purpose (yeah, I get the humor after last month’s incident). The joint still doesn’t look great but it wasn’t as “gap‑y” as it seemed before cleanup. What’s more, I can attest that even as poor as this one looks, it is incredibly strong. It’s not especially pretty, but for some utility boxes, it would definitely serve it’s purpose.
So, this wasn’t a total failure and I did learn a lot from the exercise, including the injury. Which, my fingers have completely healed back, nails and all. As a result of “babying” the left index finger, I did develop tendonitis in my left elbow (which is really the forearm muscles and tendon connection). So, that little incident continues to remind me to be safe!
- A dado stack is a pair of blades, often with intermediate spacer/chippers in between which cut out a wider section of material in each pass on a table saw. [↩]