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Tom -<br>
I don't know which I find more insulting: that you deleted my post or
that the South Bend Precision intentionally excluded my size screw from
their machine. humph! So, I could resend you my post, but as
Jon Page would tell you, you can check the archives. (you don't really
need either)<br><br>
I assumed, and still do, that the original question referred to the round
head pedal plate screw, not the one's you mentioned in your opening
paragraph, though that's useful info. <br><br>
I decided to remeasure today, since I was still coming off one of my
regular summertime binges and my eyes were having trouble
focusing. I was guesstimating because that's the jump on my
leaf gauge, and it seemed to be somewhere in between. Here's what
I'm seeing now, with the un-Lasiked, myopic 60 or so year old eye:
Over the interval of 4 gauge teeth on the 28tpi leaf, the gauge teeth go
from bearing against the 'front' peak to bearing against the 'rear'
peak. As I try to place more of the entire quage on the full length
of the screw, any semblance of congruency fails. So what could that
be? 28.5?<br><br>
As far as whether Steinway made custom screws, I hope someone with more
knowledge can speak up. I know that there are sizes, certainly in
wood screws, that <i>were </i>standardly available at that time, though
no longer. As I told David I., look at the old keystop rail prop
pins & nuts, or the old action rail screws.<br><br>
<br>
At 12:03 PM 7/22/2008, Tom wrote:<br>
<blockquote type=cite class=cite cite=""><font size=2>Hi, David I. and
David S., and Colleagues -<br>
<br>
I took a look at the pedal plate on an 1889 Steinway, the oldest on the
premises at the moment. (I figured if there were an oddball thread
to be found it would be more likely the older the piano.) I found
that screws anchoring the pivot rod were garden-variety No. 8 32-thread x
1/2 inch flat head machine screws. We have a box of these screws we
keep on hand for the occasional replacement.<br>
<br>
To David S.: 30-thread would be very odd indeed. There is no
current or recent (20th century) American, Canadian or British standard
thread at 30 pitch. And that's why many thread guages skip that
pitch. Metric threads don't quite approximate that either. I
accidentally deleted your post on the topic, but I recall you mentioned
measuring your screw diameter at something like 0.213 inch. That
would be about right for a No. 12 screw, which should be 28 pitch in the
fine-thread series.<br>
<br>
There would be no point in S&S using special threads for this
part. Common hardware is available to do the job and it would be
much more expensive to have custom-made screws and custom-made taps,
etc.<br>
<br>
Sidebar: I have a very nice South Bend Precision Lathe that cuts 48
different thread pitches. Conspicuously absent from that list is
30-pitch.<br>
<br>
Another Sidebar: It is not desirable to set these screws
"gorilla tight". Notice that the pivot rod makes contact
with the screw very much off center from the axis of the screw.
Using a screw this way would be considered abusive in some circles; it
will cause the screw to break well below the tension needed to break a
screw with concentric loading. However, tightening the screw
moderately snug is more than adequate to hold the pivot rod.
<b>It's another example of an elegant mechanical design from
S&S!!</b></font></blockquote><br>
Are you being sassy?<br><br>
Regards<br><br>
David Skolnik<br>
Hastings on Hudson, NY<br><br>
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