I have always used prop reamers, but on my gas engines the hole needs to be 10mm to fit my DA 50does not go that big. I have a drill press and I got me a 10mm bit and I have a drill press vice. All you have to do is find a bit the same size as the current hole in the prop and then use it to line up the prop on the drill press vice and clamp it down good so ther is no chance of movement and then I switch to the correct size bit and drill it dead center. Works every time. Perfect. On small props my reamer will fit I use it so I don't have to spend the time to do all the other besides on my gas props I have to drill 4 mounting holes with the prop guide drill jig anyway so I go through the effort.

Norman Ross Jr.