If the strobe pattern is like those used to calibrate a turntable's speed, you may get accurate results with the smaller version. Before pursuing a size corrected version of the strobe, do a test: Make a photocopy of the strobe that's visibly smaller or larger than the one you have. Try them both to see if they give you the same result. I suspect they will.
From: Steven Smolian <[log in to unmask]>
To: [log in to unmask]
Sent: Wednesday, March 30, 2011 4:08 PM
Subject: Re: [ARSCLIST] Shrunk strobe?
I recall that there is a small reduction in size to a Xerox copy in each
generation. Does anyone know what percentage this reduction is?
I recently purchased a Xerox copy of "Mechanical Service Instructions" for
various Webster-Chicago wire recorders.
It includes a strobe. By its size, I assume it is to be placed on the
I'll have to make a larger copy so it will give an accurate reading when in
use. I realize that I have to make an additional allowance for what I loose
when making the corrected copy and that this may not be a first generation
The speeds start at the outside at 107.44 rpm, then 109,08 rpm, and increase
successively to 116.13 rpm on the most inner of the 6 sets of dots. Correct
speed for the wire is 24 ips, at least in one source.