At 11:41 AM 9/26/05 -0700, you wrote:
>Yes, I used the finest grit auto supply stores offered for valve grinding
>car valves. I can imagine your shocked tone of voice in your typing.
Gary,
Hmm . . . well I tried not to sound too shocked. (The crackling noise
you heard in the background was just me . . . being defibrilated.) What I
didn't want to do was jump to conclusions because "lapping compound" could
have been anything, every ultra-micro-diamond compound, so I had to ask
first. I'm surprised you had any success with such a coarse grit although
as Geoff points out, it worked and further demonstrates how forgiving a
steam engine can bem but I wanted to suggest more appropriate alternatives.
A much better and more convenient choice would be emery paper, say a
600 grit or. The valve shouldn't be lapped into the cylinder or vice
versa, especially brass or bronze parts. Lay the emery paper on a dead
flat surface, a piece of plate glass will do, and stroke the valve and/or
cylinder across this. [News Flash - Mike Chaney's post has just now
appeared and his instructions are highly recommended.]
Also, most Aster kit instruction booklets have excellent explanations
of how to do a two-stage emery paper lap and this information should
probably be spread around as a guideline arouind which people might work.
(A two-stage lap might not always be necessary.)
Although automotive lapping compounds (like Clover Brand) can be had
in ultra-fine (1200gr) you usually can't find that grit off-the-shelf and
then only in 1/4 & 1lb tins, enough to last the entirety of the garden rwy
live steam world the rest of its life! The Clover automotive valve
grinding "sets" (two connected tins) usually have half-60gr and half-260gr
(at best) which hardly qualify it as a "lapping" compounds in the usual
sense of the word. Much too coarse.
On the other hand, high quality emery papers of at least up to 2000gr
can be had in individual sheets at almost any decent auto paint & body
supply (Sherwin-Williams, PPG, etc). I hope this is of some use.
Regards,
Harry Wade
Nashville Tennessee
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