Harry, You made mention of boring the driver crank pin holes and then turning the crankpin ends without moving the angle on the compound rest. This is precisely what I did on my large 4" x 5" single cylinder marine engine, on it I bored the piston and turned the piston rod so the fit was absolutely perfect. It would take a lot of hand fitting if one tried to make a new set-up and expect perfect seating in the tapers. Jesse MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.