[Harp-L] Re: Vibratory Stress Relief

[Rick Epping <rickepping@xxxxxxxxx>]

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

>
> ------------------------------
>
> Message: 10
> Date: Mon, 3 Nov 2014 15:23:26 -0500
> From: Michael Easton <diachrome@xxxxxxxxxxx>
> Subject: [Harp-L] Re: Vibratory Stress Relief
> To: Harpl list <harp-l@xxxxxxxxxx>
> Message-ID: <B7A09B68-7DDF-4AF6-9CC3-D7BDC309343E@xxxxxxxxxxx>
> Content-Type: text/plain;       charset=windows-1252
>
> Hi Rick,
> Since I get the digest I donât know if any replies came in yet after your
> posting.
>
> Have you tried checking the other reeds before placing the plates in the
> ultrasonic?
>
> Iâm guessing the change in pitch might not be the reed relaxing but the
> scraped reed material flaking off the reed that is contributing a bit to the
> raise in pitch.  Yes, it could be helping with speeding up the relaxation
> but Iâm just saying there might be a bit more to it to contribute to the
> change in pitch.
>
> Iâve used files, very sharp dental burs and Shofu Brownies in rotary tools
> and found the Brownies required the least amount of adjusting since the
> reed was being
> polished, followed by the dental burs then files and scrapers requiring
> the most adjustments after replacing a reed.
>
> I think in general if you can place a set of plates in an ultrasonic
> before checking the tuning you can get a more accurate reading due to the
> lack of saliva and oxide buildup
> hanging around on the reeds and to some degree the windsavers on models
> having them.
>
> Mike
> www.harmonicarepair.com
>
>
>
>
> On Nov 3, 2014, at 10:46 AM, harp-l-request@xxxxxxxxxx wrote:
>
> >
> > Message: 11
> > Date: Mon, 3 Nov 2014 15:37:58 +0000
> > From: Rick Epping <rickepping@xxxxxxxxx>
> > Subject: [Harp-L] Vibratory Stress Relief (VSR) for reeds
> > To: "harp-l@xxxxxxxxxx" <harp-l@xxxxxxxxxx>
> > Message-ID:
> >       <
> CAJFTUGwuePAe6FTPu0YFAkALaSq2dhusPDf1n8OxzFAmEJNB2Q@xxxxxxxxxxxxxx>
> > Content-Type: text/plain; charset=UTF-8
> >
> > Hi folks,
> >
> > This message is about one possible benefit of using an ultrasonic cleaner
> > on newly replaced reeds.
> >
> > The work that reeds are subjected to through such procedures
> > as profiling, riveting, centering, chamfering, curvature adjustment and
> > gapping, adds stress to the reeds.  As the tuning of a reed can be
> affected
> > as a reed de-stresses, the Hohner factory gives newly assembled
> reedplates
> > a rest period to de-stress before tuning.  Alternatively, Asian harmonica
> > factories heat treat reedplates to de-stress them.
> >
> > In my experience, new replacement reeds that I have riveted onto a
> > reedplate tend to go up in pitch over the course of a week or so, and
> > require an additional tuning once they become stable.  Lately, however,
> > I've been using an ultrasonic cleaner in an attempt to VSR treat plates
> > with newly replaced reeds, and find that after using the cleaner's
> maximum
> > time setting of 8 minutes, new reeds increase in pitch by as much as 8
> or 9
> > cents.
> >
> > I've only been paying attention to this effect for the last half dozen or
> > so reeds I've replaced and have not as yet experimented with employing
> > longer periods of VSR, but it looks like it might be a useful treatment
> for
> > quickly stabilizing a reed's tuning, if not also for delaying the onset
> of
> > reed failure by elimination of residual stress before a new reed is
> > subjected to playing.
> >
> > More on the subject of VSR here:
> > http://en.wikipedia.org/wiki/Vibratory_stress_relief
> >
> > Best regards,
>
>
>
> End of Harp-L Digest, Vol 135, Issue 8
> **************************************
>