Just been following rick's notes for dismantling a 50mm f1.8 canon FD lens, but I have hit a hurdle early on. The screws are so rediculously tight, I cant get em out.
You must use a screwdriver with a large handgrip. If you are using a driver that has an integral grip/blade, the diameter will be way too small to offer enough purchase - the grip diameter on integral drivers is chosen so that one does not over torque the screws on tightening down. Unfortunately the mount screws on the nFD lenses were torqued down using a power tool, thus they are very! tight. Also make sure the screwdriver really fits the screw +head.
Sometimes the application of a little heat can help. Use a small electric soldering iron, allow to fully heat up and place the bit on the stainless steel mount ring over the location of each of the tapped holes in turn. Heat for 30/40secs and immediately try and remove the screw that is located in the heated location.
