On Jul 18, 2007, at 3:19 AM, Joe and Cass Leone wrote:
On Jul 18, 2007, at 2:17 AM, Rick Dempster wrote:
Hmm...don't think I'd do that Ken.
Naah, I wouldn't do that either. You won't accomplish anything. First of all, a steady cooling or heating will do BOTH
components the same because it IS steady. Both components are (basically) brass. Now while I have always suspected that the reed material is slightly different in amalgum, it isn't that much different. The reeds are designed to be 'spring' material, and therefore have to be hardened somewhat. The reed plates are softer by comparison.
I ascertained this through ascertainment by taking apart almost every sort of gizmo in my long lifetime. As a teeny bopper, I used to strip copper brass & alum out of things I found in the city dump (for spending money). A file or hacksaw touch across metals will give you a sort of 'rule of thumb' as to the makeup of a metal. The reed plates are slippier (using turpentine as a catalyst). The reeds will give the file more of a 'bite'.
When fitting a replacement reed, I prefer to work on the SLOTS if the reed doesn't line up centered in the slot.
I'd reckon that after a certain
amount (?) of time the plate and the reeds would reach the same temp.
Sure, time is the factor. A 'dipped' harp will react one way because it is momentarily adding weight/gap reducing factors. A 'steadily' cooled (or heated) harp will 'steadily' equalize.
and there'd be no difference.
Sure, no difference.
In fact I'm a bit confused by Joes post.
Wouldn't be the first time. I don't express myself well in written word.
In the distant past I have removed bearing outer-races from motor-cycle
crankcases (aluminium-alloy cases, steel bearing races)
Yes, AND these races are not only CHROMED but also case hardened.
I heated up the cases in the oven (causes expansion) then took them out
and dropped ice cubes in the bearing outer- races (causing
contraction).
Yes, and the races contracted a whole lot less than the alum expanded. Alum is a wonderful metal and has many fine applications but NOT in engines. The modulus of expansion is too great. Two points: 1... This no longer matters as engines are rarely required to run past X number of years anymore. Planned obsolescence, and there are only so many 'cycles' designed into anything any more. 2... Motorcycle engines are premised on the factor of saving weight. And as long as there are cooling fins on the alum to dissipate heat, and air flow is sufficient, these NON shielded fan engines can operate ok. In hot climes, better get a liquid cooled.
It used to be that alum engines had cast iron liners in the cyllinder heads.
The bearing races fell out with the lightest of taps.
Now, if you heated the harps, I'd reckon the reeds, being lighter in
gauge, would reach maximum temp. before the plates, so that would narrow
the clearance between reed and slot.
Then again, the plates, taking longer to heat, might just conduct the
heat from the reeds (ie 'rob' the heat) and the reeds not heat up any
faster than the plate.
I would say yes. The reeds DO (after all) contact the plates, ARE riveted/welded/screwed. The plates would be a heat sink for the reeds.
I'm talking heat, because thinking in reverse (ie cooling) is something
I have difficulty getting my head around.
No difference. Modulus of expansion is inverse to modulus of contraction. The only 'real' altering effect are components of different material(s). i.e the Barometer.
I mean, is coldness just the abscence of heat? er.... I have a feeling
Joe might come to our aid here...
Coldness is Black, Heat is white. The absence of light is dark, the absence of dark is light. White paint is opposite of black paint. Coldness is negative heat. Heat is negative coldness. Refridgeration is opposite of furnace....Hey, I'm getting too silly here.
smo-joe
RD
Joe Leone wrote:Ken Deifik <kenneth.d@xxxxxxxxxxxx> 18/07/2007 15:56:14 >>>Another theory of mine is that since the reed plates have a much larger mass than the reeds, cold ANYTHING will cause the modulus of contraction to differ between THEM and the much much smaller mass reeds. This also may close up the tolerance(s).
Well, I started this with my question, and with full faith that youse
all
would come up with the goods and you haven't failed. I thank
everybody. I've learned alot.
I'm totally intrigued by Joe's reply. I have a harp whose
responsiveness
leaves alot to be desired, and which I unfortunately need to use. I'm
going to stick it in the fridge tonight and see how it performs in the
morning.
I will report back.
Hopefully my wife will not be annoyed. She already thinks I'm peculiar.
K
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