On Mon, 18 May 2009 20:06:35 -0700, the infamous "Michael Koblic"
scrawled the following:

Jim Wilkins wrote:

Lapping implies a rigid guide holding the abrasive.

OK, now I get it. This was the critical element I was missing. So to lap,
say, a lathe way, you would spread the paste on a flat piece of brass or
aluminium and rub it on the ways?

I won't even ask how they lap the automotive valves...

I learned this way: apply lapping paste to valve seat, insert valve,
stick rubber suction-cupped, hand-crank egg-beater/drill thang to
valve face, and turn handle. like this: http://tinyurl.com/pdscsu or
http://www.goodson.com/store/product_images/b1_imgshop_528.jpg
I have no idea what grit we used in 1971/72.

Here's another semi-manual way:
http://fly.hiwaay.net/~langford/corvair/valvejob.html

And a VERY manual way: http://tinyurl.com/r6ab8a or
http://www.holtsauto.com/images/products/repair-and-maintenance/maintenance/holts-valve-griniding-kit-hi.jpg

--
No matter how cynical you are, it is impossible to keep up.
--Lily Tomlin