Hi Guys, I'm new to this forum so you'll have to bear with me. I bought a General/Samona dovetail jig and like some of you the results have been frustrating and full of expletives.
I went online and searched dovetail jigs and came up with a list a mile long. One of the things I discovered is that a lot of the jigs are functionally identical so I downloaded and read manuals. Their setup was identical, only a few features were different one to the next. Porter Cable was one of the better manuals albeit the jig was substantially more expensive than the functionally identical General/Samona/ShopFox.
One of the things I discovered is the crucial measurement: that is the depth of the router bit. Change it 1/64th at a time! Secondly, dedicate one router to that bit, adjust it and never change it. That means if your dovetail joint is blind between 1/2" plywood and 3/8" plywood, you do the setup for that joint, label the router and never use it for anything else. If you have to do a 3/8" into 3/4", get another router. I pick up used routers in garage sales and rummage sales. Stay away from the offerings in flee markets (at least in my area - Ontario) they sit for years in the dust and dirt, only to be charged a small fortune (because they're old.)