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On Thu, 21 Jan 2010 04:52:32 -0700, Gary LaPook 
wrote:

> The following was originally posted on July 4, 2009 as message #8949.

Gary, I clipped almost everything from the above post that showed your
Bygrave version built on a thin chrome plated tube, from a sink drain, I
think.  Assembly was pretty straightforward using clear, sticky on one
side film for protection and as construction material, though you warned
about watching the direction of overlap to avoid "ratcheting".

My version, built on a 1-3/4 inch diameter cardboard tube 11 inches long,
is not as nice as that or your newest larger diameter cylindrical rule
with the HR1 locking feature.

I just didn't like the idea of close fitting aluminum tubes rubbing on
bare paper, lacquered or varnished paper, or even plastic coated paper.
Including the thin felt layers to gently rub on any of the above surfaces
is my preference.

My cursor tube is opaque, with an oval window cutout and pointer for the
short tube, and a pointer for the long tube.  I have a stop on the outer
tube so the cursor tube window mark is lined up with the lowest spiral of
the midle tube (which reads 4 degrees at the lower end); and the basic
instruction diagram is printed half on the middle tube and half on the
cursor tube right over the stop line.  There is still about four inches of
blank paper showing at one end of the inner tube; can't seem to make it
any shorter than that and still have enough travel and easy handling.  The
middle tube can be removed accidentally from off the end of the inner
tube, but it doesn't happen during calculations.  Does the Bygrave inner
tube telescope at all, and have a knurled cap to prevent this accidental
disassembly?

--
Richard . . .


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