For my hot air engines I use a wooden lap, I should get some courser grinding paste, the stuf I have is very fine(and cheap), Got 250gm pot yrs ago. Turn up a bit of wood, a firm fit in the bore. Cut a slit up half the length, make the lap about twice the length of the cylinder. To adjust the tightness either put a thin wedge, or a wood screw in the slot. Cover it with paste, mount it in the lathe, and turn it on sliding the cylinder up and down. If you need to use a finer paste you’ll need another bit of wood, you can’t clean the old one. Its cheap, tends to be a bit slow (maybe a good thing), proberbly not as accurate as a propper lap, but you can have what ever size you want. There is a grinding medium that self destructs, ie., breaks down and does’nt embed in the article being lapped, someone will come up with the name of it. Ian S C
Edited By Ian S C on 10/01/2012 11:16:33