In 2006 Festool released their Domino joining system. At the time, I was working at a store that sold them. I can say with a fair amount of perspective that there was a large group of woodworkers who were collectively wetting themselves over this machine. Incontinence isn't something to make jokes about. Communal voluntary incontinence is something else, though.
As things would have it, early adopters learned pretty quickly that it was great... but there were issues. That's one of the perks of being an early adopter of any new product, so I'm not picking on Festool here. Not all of the fences on the early versions locked down the height adjustment adequately. As a result, joints weren't lining up as cleanly as they should have. Some of the brave souls took to performing their own modifications. Others simply cranked down on the tightening knob and learned to deal with the fence when it deflected. Festool eventually released an updated fence, and I'm told that the problem was solved. I'm still having problems with mine, because I've heard stories about damage due to over-tightening.
So who is Ron Wenner? He's the guy who made using this machine a lot easier.
someone on Festool Owner's Group had taken to bolting a piece of plywood to the bottom of the Domino. The idea was to make a rigid, fixed fence, and simply using the machine upside down. It wasn't the most eloquent solution, but by God it worked. Not long after, Ron Wenner shows up on the scene with a milled aluminum plate. It has a slot down the middle, to make it easy to see the alignment mark that's scribed on the bottom plate of the tool. It's beefy. And it has different offsets: Positioned one way, it centers the mortise in 3/4" stock. Flipped over, it centers in 1/2" stock.
I wrote to Ron earlier today to let him know how happy I was about his jig. For those of you who are interested in getting one for yourself, look for response #188 on page 7 of the above mentioned thread on FOG.