Temperature Problems?

[Chris Ghent]

It was helpful to see Jim's comments about reed frames. I have wondered if concertinas that stick when cold may have a different "fit" of the reeds in the reed frames, or if the metals used for the reeds and frames would make the difference, or if some leather (or plastic) valves may be less pliable at lower temperatures.

A quick trip into Machinery's Handbook, (which must be the most poorly indexed reference work ever written, more than 2000 pages of data and only about 200 items in the index) when I was actually intending to dive into O'Neills 1860, which would have been more fun, shows that the linear expansion coefficient of carbon steel is .0000063 while the same figure for brass is .00001. This means brass expands and contracts about 60% more than steel for any given temperature rise or fall.

 

If you imagine the brass frame shrinking in the cold faster than the steel reed it surrounds, it would be fair to say that for any logical (ie. as used in a concertina) clearance between the two, there is eventually a temperature at which the two must meet, especially at the tip, as the contraction of the frame along its length will be greater than across.

 

As a feature of a better concertina is likely to be closer clearances in the reeds, you could argue a better concertina would be more likely to develop this problem earlier; that is, at a higher temperature... However, erratic clearances could also create the problem early.

 

More than you probably wanted to know...

 

Chris

Edited October 7, 2004 by Chris Ghent

[Alan Day]

Very interesting Chris,you answered the theory with the technical information to back it up.A close fitting reed of say a Jeffries does seem to be effected by temperature drop as I have experienced.Only certain reeds however and as you suggest, probably more tight fitting than others may be.I wondered at first if the reeds were producing condensation and the moisture swelling the wood around the reed,but on reflection the problem would not be solved so quickly with warmer air being pushed into the concertina.On average it only takes about five minutes for the reeds to start playing again.So the expansion / contraction theory seems to be the most likely.

Your thoughts Brian on speech being effected by the cold,is possibly muscle tightening which I suggest is possibly why so many athletes suffer from muscle pulls during sudden temperature variations.I do not think enough work has been done on this subject.Even playing the concertina on a cold corner of Sidmouth Sea front and I suffered a muscle problem in my hand,for the first and only time.

Thanks for an interesting discussion.

Al

[Alan Day]

Thinking further on your information Chris,Would I be right in saying that in certain lower temperatures the notes would sound sharp? The concertina should be in tune with itself however unless some reeds are warmer than others.

Have we a market here for concertina electric blankets or Wendy`s crotcheted wooly covers ?

Al

[Chris Ghent]

Alan,

 

I'm no expert in metallurgy, and while the comparative expansion/contraction figures between brass and carbon steel are right, the above is just conjecture until someone does the mathematics to find out whether those numbers are sufficiently high to shift the clearances enough to make the reed foul the frame within a possible temperature fall. My own attempt came out with a tiny shift for an average reed (7/100,000ths of an inch for a 20 degree shift in a 15mm reed) but I am hopeless at mathematics when operating to the right of a decimal point.

 

What has occurred to me since I wrote the above is, why don't the reed shoes fall out of the pan as well? I am imagining wood will contract less than brass. Perhaps the small amount of compressibility in wood keeps them trapped. Or maybe the expansion contraction thing is not the reason reeds have this problem.

 

As far as pitch climb from contracting reed tongues due to cold, I have no idea, though if my mathematics were to be right the contraction is tiny, hence negligible change. Perhaps Dana or Tom Tonon would have an idea.

 

Chris

[Brian Humphrey]

Alan, you mentioned effects of temperature on speech, and you raised some interesting issues. The comments and speculations in my previous post were actually about possible effects on hearing... but were you perhaps telepathically receiving some of my unstated thoughts? Yesterday, I had a lively discussion with a colleague about the possible parallels between the ceiling fan effect and vocal vibrato (another complex and much debated phenomenon). We are thinking about taking a fan and a squeezebox or two into the voice lab at work to do some acoustic analyses ... if we get that little project off the ground, I'll plan to post something on the "ceiling fan" thread.

 

Chris, I'll add my thanks to Alan's for your information.

[JimLucas]

...were you perhaps telepathically receiving some of my unstated thoughts?

Do cold or ceiling fans have an effect on telepathy?

[darticus]

Hot weather makes my concertinas owner get thirsty and drink beer, causing speed problems.

BEER? Thats what I should have taken up. Concertina too hard! Easier with Beer but sounds strange. Ron

[JimLucas]

Hot weather makes my concertinas owner get thirsty and drink beer, causing speed problems.

 

BEER? Thats what I should have taken up. Concertina too hard! Easier with Beer but sounds strange. Ron

 

Most folks find that singing with beer accompaniment rarely sounds good. (Alternating the two, not so bad, depending on the singer.) However, I find that playing bones with one hand while using the other hand to hoist a glass to my lips works quite well.

Edited June 16, 2016 by JimLucas