[CW] What is a Sideswiper, or Cootie Key?

[Richard Knoppow]

     I thought of that after sending.
     I measured the main springs for all three keys using a 
precision micrometer, here is the result.
1920 Original Thickness =0.013", length of active section 0.365"
1944 "         "        =0.013", length of active section 0.365
1961 "         "        =0.013", length of active section 0.370
    I also measured the length of the pendulums from the front of 
the main spring, that is the flex point to the effective back end 
where it hits the damper, all the same.
    At some time in the past I measured the speed ranges of all 
of these plus a couple of other bugs using a scope. I've also 
used a General Radio Stroboscope. I lost my notes but do remember 
the fastest was the Bunnell J-36 and the slowest was a very old 
Speedex, made before E.F.Johnson got hold of them. I also have a 
couple of TAC keys but didn't have them when I did the speed 
measurements. They feel about like the Speedex.
     Now something else. I just tested all three keys on an 
oscillator, speed doesn't agree with the above mechanical 
measurements.
1944: is the fastest
1961: intermediate
1920: slowest

  I tried swapping weights around, no change. So, what can be 
difference?  The strength of the springs probably due to spring 
material. I measured them using a spring scale:
1944 3 oz
1961 2 oz
1920 1 oz
    These are approximate although I did try to make the 
deflection equal.
    In general springs weaken with flexing not when under 
constant tension or pressure. The main springs in a bug don't 
undergo much flexure and certainly never get close to the elastic 
limit of the spring unless its accidentally stretched somehow.
    I don't think the added return force of the dot contact can 
affect the speed that much but I can measure the pendulum speed 
without the dot spring making contact by using the stroboscope. 
Maybe will do that but I don't think it will make any difference.
       Thank you for putting me on this minor scientific 
investigation. Maybe I an expand it into a master's thesis.
    I don't have an answer but its an interesting puzzle.

On 4/12/2018 2:51 PM, D.J.J. Ring, Jr. wrote:
> Richard,
> 
> I  will guess from what Don said that he means the pendulum's 
> main spring is stiff - which is not uncommon.  The 1920 versions 
> of Vibroplex used a thinner spring which made them slower and 
> less likely to have dot bounce.  I have a 1925 Original which 
> sends like a fine instrument.  I have a 1960s Presentation and 
> Original which also send very well but they are a bit more "high 
> spirited" with a stiffer mainspring, but they respond well.  I'd 
> be afraid of traveling with the 1925 because the mainspring is 
> just that much thinner and I've broken some mainsprings in my 
> days from shipping them without restraining the pendulum with 
> rubber bands or twist-ties or string.
> 
> 73
> DR
> 
> 
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-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL