Hi folks,

Keith, this is the second time I've joined this list. The first time (some
months ago) I quickly retreated on the fear I'd probably do more harm to my
mp than good.

Well, I'm back and I believe now I should be able to apply some of the
knowledge shared here, at least to facing work.

I now have the Babbit 0-flush facing gauge, a stack of automotive feelers up
to 0.035" (who makes them in thicker sizes?), a plate of sheet glass, and
several grits of abrasive paper.

My initial question has to do with the mention of striving for a perfect
radial arc, or determining what parts of a facing are "uneven." Given any
particular tip opening, is there a way (an equation, with defined variables)
to calculate what the measurements with different-size feelers should be for
a given mp? I suppose I'm wondering whether universals apply, or whether I
should be limiting the "universals" to the scope of a particular mp
brand/model? I downloaded and looked at the facing curve.xls file and
noticed a column titled "Spec." How does one arrive at these measures?

Comments and pointers to pertinent past messages deeply appreciated. I
probably won't touch the innards of any mp until I'm happy knowing what I
can do to improve things at the "surface" level.

Wally Moore

> [feelers] to 0.035" (who makes them in thicker sizes?), 

No one does that I know of.  There is no easy solution to get larger 
sizes.  I tape several together and carefully measure the thickness 
with calipers in several spots where they will touch the facing.  You 
should mesure all your feelers with calipers, since they do vary 
some.  I plan to try gluing a stainless steel set together.  I also 
may rig up some gage blocks (used a standards to calibrate gages) for 
use.  It is a good idea to check your calipers with a gage block.

> I downloaded and looked at the facing curve.xls file and
> noticed a column titled "Spec." How does one arrive at these 
measures?

I think I listed as "Spec" an example a classic Link facing curve I 
found from one of JVW's web posts.  I ususally plot the existing 
facing curve and look at a fitted arc through it.  I then decide if 
this should be the goal.  If not, I decide on the goal facing length 
and tip opening.  Then I fit an arc between those 2 points.  The 
curve continues to a theoretical .000" feeler gauge point where the 
arc is tangent to the table.

> 
> I probably won't touch the innards of any mp until I'm happy 
knowing what I can do to improve things at the "surface" level.
> 

Actually, playing with temporary putty baffles on the innards is the 
safest way to start tinkering with mouthpieces.  You can always take 
the putty out.

Hey Keith,

Paul C gave me some pointers in a couple of private emails.

> I think I listed as "Spec" an example a classic Link facing curve I
> found from one of JVW's web posts.  I ususally plot the existing
> facing curve and look at a fitted arc through it.  I then decide if
> this should be the goal.

Okay, my expectations are beginning to face reality. I was also wondering
about this spec business in connection with the notion of blueprinting, but
I suppose you'd have to be privy to some inside mouthpiece maker data from
the start--assuming it's not exactly in the public domain..

I'll shuffle back now and spend some more time reading through the message
base.

Wally