Nature of tuning pins - the return of the tapered pin?

[Kendall Ross Bean]

Ron Nossaman wrote~

>Yes, this is the fault of our parts suppliers, not the part 
>manufacturer. Denros are, I expect, sold to the parts suppliers
>as 7.1mm pins, and the parts suppliers sell them to us as 2/0.
>If they were labeled what they actually are, it would be our problem
>to figure out what we actually want. Look at Roslau wire. Being 
>metric, it doesn't correspond to the gage numbers it's sold as either.

Ron~

Aha, so this is what has been happening. When AMSCO went out of business,
there were no more real 2/0 (.282") pins!

-Our suppliers have been passing the Denros (metrics) off to us as if they
were standard U.S. sizes!

Actually, this seemed like the ideal explanation, until I went out and miked
2 of the most recent sets of blued pins I have gotten from Schaff (Denros).

Now I suspect it's just poor tolerances. Here are the results of my latest
micrometer readings: ( I checked several pins from each batch)-

Denro 2/0 x 2 3/8" blued: Tapers from .281 - .282" at the bottom of the
thread to .283 - .284" at the top of thread.

Denro 3/0 x 2 3/8" blued: Tapers from .284 - .285" at the bottom of the
thread to .287 - .288" at the top of thread.

Concentricity didn't seem to be much of a problem, pins seem concentric in
cross section within .0005" to .001"

But the tapering, from bottom to top of thread, seemed pretty uniform among
the pins. What are they doing, I wonder?

It seems they actually are shooting for the U.S. measurements, .282" and
.286". -If you average all the measurements on a single pin, it's pretty
close! But you have to admit, that's a pretty wide spectrum of micrometer
readings. 

However, if you ever have to drive them in further, they should get tighter,
all along the thread!

Ron Nossaman wrote~

>It's easy. I make up a block by epoxying a 9mm Delignit cap
>on a low density multilam maple, double drilling 1/4" and 6.8mm. 
>No bit cooling, no high precision setup, no problem. Very good
>uniformity and torque with 7.1mm Denros out of the box - no micing.

Ron~

I assume that means you drill the 1/4" (.250") hole to depth first for the
low density maple multilam, and then drill the 6.8mm (.268") just through
the Delignit cap? Where do you get the 9mm  (3/8") cap? Do you bandsaw it
off a block of Delignit, then run it through the planer? Why epoxy? Aren't
there adequate wood glues?

~Kendall Ross Bean

PianoFinders
www.pianofinders.com
e-mail: kenbean at pianofinders.com
 
Connecting Pianos and People


We concluded that it works better on paper than it does on wood." 
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from the inventor's plans.
  


-----Original Message-----
From: Ron Nossaman [mailto:rnossaman at cox.net] 
Sent: Wednesday, July 09, 2008 1:25 PM
To: Pianotech List
Subject: Re: Nature of tuning pins, and miking sets, shop made blocks.


>The fact that Denros seem to run .002" smaller than specified  is also 
>something I have observed. Sometimes it works out fine, other  times I 
>wish the pin were what they say it is. Time is money, and we do  depend 
>a lot on our parts suppliers to provide uniform, acceptable parts  that 
>we don't have to mess around with.

Yes, this is the fault of our parts suppliers, not the part manufacturer.
Denros are, I expect, sold to the parts suppliers as 7.1mm pins, and the
parts suppliers sell them to us as 2/0. If they were labeled what they
actually are, it would be our problem to figure out what we actually want.
Look at Roslau wire. Being metric, it doesn't correspond to the gage numbers
it's sold as either.


> When you say shop-made 1/4-sawn blocks, does that mean you make them 
> up from scratch? Glue them up and all? That's admirable. (But a lot of 
> work, isn't it? Wouldn't it just be easier to go with a Bolduc block? 
> Or have you found some inconsistencies, like with tuning pins? ;-). 
> You must have some very accurate woodworking machines: planers, table 
> saws, and a nice clamping press. What kind of glue would you use, that 
> wouldn't cause the oxide rings on the tuning pin threads?
>  
> I haven't tried making my own pinblocks, or tuning pins yet; although 
> I know it's possible.

It's easy. I make up a block by epoxying a 9mm Delignit cap on a low density
multilam maple, double drilling 1/4" and 6.8mm. 
No bit cooling, no high precision setup, no problem. Very good uniformity
and torque with 7.1mm Denros out of the box - no micing.

Ron N