I have never made these by hand, but if or when you start doing it with a router. If the joint is loose, lower the bit (more bit sticking out from the router), if they are tight raise the bit in the router. Doesn't take much, less then you would think, I move it 1/64 at a time until I get the fit I want. Dovetails are nice, but no one can do them without test pieces, not even Norm Abram ..lol...a friend of mine has one router he uses for dovetails, never takes the bit out or uses the router for anything else...lol...I can't afford to do that, so I keep the final test piece with my jig, so I can reset my router and I still have to do test pieces. Final note don't even think about doing dovetail joints with a cheap router, it won't be near accurate enough or hold it's depth long enough to do the job, you'll just go crazy, and if you have a choice, use 1/2" shank bits, your cuts will be much better.