Bruce McCrory
If only it had been this easy.... I should have stolen nearly the same picture from the HD site. Actually, almost did.

Just know that a lot of weight and force is required to jamb the bit into the guide and hit the trigger at the correct place. The kicker is watching/hearing the screw fall through to the ground (stones) below when alignment misses the joist.

I grump but the design is quite good, and simple. Unlike convoluted Kreg-like fiascos. It's tough, too. There has to be another several thousand feet of life in the jig.

Thanks for the kudos. I spent the entire summer in working on it. The framing and deconstruction was most of the work. The pretty parts look nicer.