Re:Lapping

Maybe I should have made a clearer statement-

Lapping, where you use a tool called a lap, either a purchased one or a
purpose made one, is a very good and usefull process. You can buy flat
laps and clyndrical ones and you can make them from lots of materials.
But you use a lap against a part, not two parts.

If you simply put an abrasive between two machined parts and wear away
some of each part, you are NOT lapping, just wearing out parts. They
might get smoother and shinny but you are not improving their fit or
usefulness. They will not become straighter or flatter. In fact,
telescope makers make their mirrors by grinding two surfaces together to
make them curved.

ron ginger