Subject: [Harp-L] Re: Vibratory Stress Relief

[EGS1217@xxxxxxx]

Hi Rick:
 
While the focus of this discussion is very interesting, I'M a bit  more 
curious about how the ultrasonic works on your valves since I too  have a thing 
about keeping the valves clean. As THE Hohner guy - are you still  using 
Hohner's 2-part valves or have you switched to another type which can  
withstand the ultrasonic vibrations better? 
 
 
I've always thought (or at least heard) that the valves would come off if  
one cleaned a chromatic that way. I bought a really nice ultrasonic machine  
years ago --with as big a container as I could find which was still  
affordable--specifically for my harmonicas. At least I planned to try it  for 
everything except the reedplates, but haven't really used it other than  for 
jewelry and eyewear.
 
Now you've definitely piqued my interest - especially for my collection of  
CX-12's!
 
Can you elucidate further?
 
Thanks!
Elizabeth
 
"Message: 7
Date: Tue, 4 Nov 2014 11:45:52 +0000
From: Rick Epping  <rickepping@xxxxxxxxx>
Subject: [Harp-L] Re: Vibratory Stress  Relief
To: "harp-l@xxxxxxxxxx" <harp-l@xxxxxxxxxx>

Hi  Mike,

I regularly clean most of my harps in the ultrasonic because  they're either
partially or fully valved and the valves need to stay clean to  prevent
sticking and popping. So this morning, after noting the pitch of the  eight
reeds in holes 4-7, I cleaned in the ultrasonic one of my unvalved  harps
that hadn't been cleaned in a while and had a bit of sediment on  the
reeds. The results after noting the tuning a second time,  post-cleaning,
are as follows:
3 reeds went down in pitch
3 reeds went  up in pitch
2 reeds had no change
Average change: 0 cents
Maximum  change: up 3 cents (one reed)

I use new replacement reeds, so there  should be little, if any sediment on
them. As for bits of metal left on the  reeds from scraping or filing (I
use scrapers, files and, for chamfering, a  chisel), on average most of the
metal removal occurs along the entire length  of the reeds' long edges from
the chamfering. The "pitch-neutral" point on a  reed - that is, the point
along the length of the reed at which neither the  removal nor addition of
material will alter the reed's pitch - is, for most  reeds, about one third
the distance from the tip to the rivet pad. So the  area toward the back of
the reed where removal of material will result in a  lowering of pitch is
about twice that of the area near the tip where material  removal will
result in a raising of pitch. This even includes those low reeds  where the
unmilled weight at the tip can extend to half the reed's length or  more. I
would think that any significant deposits scattered evenly along the  reed,
when removed by the ultrasonic, should result in a lowering rather than  a
raising of pitch.

Best  regards,
Rick