[CAUT] Tuning Pin Questions - The truth about reverse thread; and Steinway parts that "glow in the dark."

[Kendall Ross Bean]

Ron~
 
Thank you. Very excellent description of what is most likely going on down
inside that tuning pin hole, where prying eyes cannot venture.
 
I wondered what all that stuff was on the tuning pins when I removed them
from the block. -Obviously, decaying sawdust. So, it apparently provides
both excellent lubricant, and frictional, properties, and also acts as
buffering agent, and doesn't cost the piano companies a cent. Brilliant, if
I do say so. Whoever thought that idea up must have gotten a bonus.
 
Thank you for a most enlightening, and I must say, entertaining post.
 
I have truly enjoyed reading your other witty and insightful postings on
both listserves over the years.
 
-Especially the one about about whether or not to use Genuine Steinway
center pins, the idol worshipper's club, Steinway parts that "glow in the
dark", and the great unwashed masses. That was a masterpiece. -Really. -I'm
not kidding.
 
I have been trying to find it again. Do you remember where it is? Can I get
reprints for all my customers?
 
Not all of us are that brave yet as to risk the disapprobation (wrath) of
you-know-who, or the torchlight processions with dogs. We need heroes and
examples like you who can call a spade leg a spade leg, especially when it's
our own leg that's getting pulled. ;-)
 
~Kendall Ross Bean
 
PianoFinders
www.pianofinders.com <http://www.pianofinders.com/> 
e-mail: kenbean at pianofinders.com
 
Connecting Pianos and People
 
> Yes I often wondered if the reverse threads weren't just a side-effect 
> of the way they cut the threads, that some salesman who happened to have 
> a silk handkerchief discovered by accident. Apparently the ratcheting 
> effect is quite apparent in silk; more dubious is the effect in 
> laminated maple or beech.

The reverse thread effect is a non-event in a pinblock. It's 
only good as a sales demo, either demonstrating conclusively 
that their product's pins will hold, or their competitor's 
pins will tear up the block.

Here's the deal. This effect is an artifact of cutting pin 
threads. Cutting threads typically produces more uniformly 
sized, parallel, and round pins, which can generally be 
considered to be a good thing, but what about the teeth?

The first time you turn a cut thread pin in a block, the 
"teeth" that aren't knocked off by the process fill with wood 
scraped from the side of the hole. Having no where to go, this 
wood dust stays in the teeth, preventing further cutting by 
said teethoids.

Now, If the static friction between the pin and the block is 
much higher than the sliding friction between the pin and the 
block, the pin will snap and pop as you turn it, loading in 
torque, until it breaks free and catches up in a hurry. Think 
Baldwin, Kimball, and the Audubon bird call, as well as 
various turkey calls.  <http://audubonbirdcall.com/>
http://audubonbirdcall.com/ The wood 
trapped in the teeth of the cut thread pins both lowers the 
static friction some, and raises the sliding friction a bunch 
(skid control), so when you turn the pin enough that the 
bottom starts to move in the block, the static friction is 
close enough to the sliding friction that there is no catch up 
"snap", and the pin turns smoothly and controllably.

That's it. The rest is cosmetics and sales games.
Ron N

 
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