Subject: Re: Lapping questions

From: [email-masked] (James Foster x2912)
Date: Mon, 6 Feb 1995 19:30:15 GMT

In article <[email-masked]>, [email-masked] (Steve Rayner) writes:
|> 
|> In a previous article, [email-masked] (James Foster x2912) says:< snip >
|> 
|> Why not use an oilstone?  50 grit is coarser than beach sand!  Even 600 grit
|> leaves a frosted finish on glass!
|> 

Fair enough question.  Even the coarsest bench stones I have are too
slow for much material removal.  They also tend to dish out and require
flattening more often when used this way.  My intent is to go up to 180
loose grit and then switch to SC wet/dry paper on a flat substrate for
final finishing.  I just want to get to the point where 240 grit paper
makes sense quicker than I do now.  

I checked the Lapping section of an old copy of Metal Handbook I have, and 
for hand lapping they recommend a flat cast iron plate with 1/16" grooves
cut in it.  Unfortunately I have no such beast.  Results on glass were 
about the same as I had before, and this is consistent with what another
poster observed when doing the same thing.  I had better luck using an oak
flooring board, since I imagine the grit embeds pretty easily letting the
whole thing act as an abrasive block.  For now I'll keep going with this
technique since it gives quick stock removal, a good finish, and a fairly
flat surface.  Final flattening with paper on the glass plate goes quickly.