RE: [ATM] First Lap Tips - THANKS!

["Jerry" <wa4guu@verizon.net>]

	As it turns out I was just rounding up some parts to make a pitch
tester. And calculating the size of the steel weight needed. Not wanting to
interrupt the free flow of coffee I decided to make a more standard tester
functionally the same as the one in the 2nd edition "How to Make a
Telescope" by Jean Texereau. Basically a rod with a point 1mm wide at the
end of a 14 degree taper with a 1kg. weight bearing on it. I have a couple
of projects I might polish soon so I thought I would try to calibrate my
coffee readings to the "Twyman viscosity tester" described in appendix J of
the book. In future discussions I will be calibrated to a widely distributed
method of describing pitch hardness. And I can do it while having a cup of
coffee.

Jerry

-----Original Message-----
From: Paul Johnson [mailto:bigatm@mn.rr.com] 
Sent: Sunday, June 20, 2004 10:41 AM
To: Jerry
Cc: Global ATM
Subject: Re: [ATM] First Lap Tips - THANKS!



Jerry,

  Thank you for the great post about working with pitch.  I'm a n00b myself
and enjoyed reading your post but i have one question.  For the steel ball
test, does one have to use coffee?  or would some other equivalent mass
work?

Also, i hope you know i'm kidding about the coffee, but not about enjoying
your post.

Paul Johnson
St. Paul, Minnesota USA
9:29 AM (UTC -6)

Friday, 6/11/2004 @ 9:12 PM; Jerry wrote:

I had a pitch lap that worked
perfect for me so I put a 1/4" steel ball on that lap and made a jig that
held a 2 pound bag of coffee (almost a kilogram for metricites) putting all
the weight of the bag on the ball and in five minutes I saw that it went
just slightly more than 1/3 of its diameter into the pitch. So I melted some
soft pitch and some hard and mixed small amounts in different ratios and
poured into 3/8" thick X 1 inch disks (about 10 X 25mm) and tested for
similar results with the steel ball and coffee. 



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