Now that the jig is built, it is time to test it. I did not take pictures during my first cut, but I did during my second test cut. I took several shots, which I hope does a good job of explaning how to use the jig. As well, there are several videos on the woodgears website that show the jig in use.
To start with, I want 1/4" finger joints, so I put in a Freud Box Joint blade set. (That was the most expensive part of deciding to build this jig!) Blades like this are not mandatory, you can make box joints with a regular dado set, or with other blades. What you really want is a blade that leaves a flat-topped cut, and my dado does not.
I layed a piece of stock down, and set the blade height to be just a touch higher than the thickness of the stock. My goal is to have fingers that are just a bit proud of the joint, which can then be trimmed flush.
Next, stand up the two pieces for the test cut. If I was building a box, I would have all four piece in at once. Snug up the pieces in the corner of the stock box, and turn the crank until the pieces are just touching the side of the blade.
One optional step here is to loosen the knob that is holding your gear in the gear block, so that you can lift it up and turn it such that the knob (or some other visual reference mark) is lined up with the two drive gears on the threaded rod. This gives a nice visual reference for lining up the gear as you turn it.
I am making 1/4" finger joints. So I need to turn the 48-tooth gear one full turn to move the stock box 1/4". Then carefully slide over the front piece of your stock, while leaving the back piece untouched. And then clamp them securely in place.
Honestly, this was one of the most difficult bits to get right, as the two pieces wanted to slide together. I would think it would become easier with practise, and also if I was using heaving hardwood stock.
Turn on your saw and begin the cutting process. Push the jig with the stock through the blade and back. Then turn the gear the required number of turns and repeat until done. Again, I am making 1/4" finger joints, so I need to move the stock double that -- 1/2" -- each time. So I turn the large 48-tooth gear, which is meshed with the small 12-tooth drive gear, two full revolutions.
And here is the result.
As an aside, I do not like the thin finger on the right edge of these pieces. However, for utility shop projects, I probably would not care. As well, these were just random test pieces that I grabbed from the scrap pile. For ideal finger spacing, I would want to use stock that is sized to be a multiple of my dado width, which is 1/4".
The joint slipped together perfectly. It was like magic. No sanding, no chiseling, no fiddling. I just slipped it in, and tapped it together. Note that this photo is actually of the very first test joint that I cut with my jig.
And that is pretty much the end. I think I'm going to really enjoy using this jig, and I can forsee a lot of use of it in future projects!