Tuning Pin Height by Danair

[Bill Ballard]

At 4:10 PM -0400 10/27/01, Farrell wrote:
>Hi Bill. I was one of those who posted on this wonderful tool. I find your
>method of getting consistent pin height intriguing. It sounds as though you
>are attaching some device that physically stops the nailer from pounding
>further than the desired depth.

Absolutely. You should start with my trust and now retired system, a 
6" pin punch (Schaff 174A) with a vertical hammershank held on by two 
small hose clamps (A machinist welded be a small blob for me, into 
which I carved a small square ledge to back up the top end of the 
shank/dowel gage stick.) With the depth gage of a dial caliper, I 
laid out the desired TP height on the shank and trimmed. Then as I 
pounded the pin in and the depth gage closer to contact, I would lean 
it backwards a few degrees while driving, and swing it down into 
parallel when checking. Yes, I have seen the tell-tale marks of this 
system on plate finishes of the '70s studio uprights, but there rods 
were probably steel (or they were in a bigger hurry).

>I have attached a thingee to my nailer and
>visually observed that the nailer was at the desired height. Your method
>sounds more definitive.

There was plenty of room for first-time fudginess, but for under ten 
minutes, it sure looked good to me.

>Can you please describe exactly where and how you
>attach exactly what to your nailer to get it to stop at height X? Got a
>picture?

Let's see, I can switch Eudora to HTML mode and paste a picture in 
the body of this email. Y'all got reasonable machines, right?

The nailer drives until the piston rod is now longer activated. That 
happens when the nailer body is prevented from moving any closer 
towards the surface (presumably because the 16p nail is driven flush 
and the fat sleeve assembly surrounding the rod has made contact with 
the surface). The sleeve assembly consists of a ~1.5" dia. plug (I'm 
sorry I don't have the parts diagram here in the office), which 
thread into the housing of the nailer. This plug is ~1" tall, and 
inside it telescopes a steel sleeve pushed from behind by a spring to 
the sleeve's furthest extension. As the nailer approaches the surface 
first this sleeve will contact is and then be pushed into retraction. 
At the sleeve's utmost retraction the piston rod no longer has the 
initial retraction it requires to trigger, and the driving stops.

All that is required for the length of the height gage is the desired 
pin height (possibly not a standard for you, from piano to piano), 
and the displacement of the rod which falls just short of triggering. 
The first comes from the piano.

The displacement required to trigger, I derived from two adjacent 
transfer punches (you could use adjacent drill bits). The sliding 
sleeve was removed from the plug, which is the fixed object in this 
assembly anyway. Using the roughly equal punch rods to set the nailer 
down on, the end of the piston rod (at rest, always a fixed distance 
out from the plug) will either be close enough to trigger or 
out-of-range and unemployed. I simply moved up in punch rod diameters 
until they held the rod high enough off the surface that although it 
may have depressed the rod but not enough to trigger the valve. 
Again, my notes are at the shop, but it seemed around .220".

TPHeight + (just under)TriggerDisplacement = gage length

This gibes me the length to which the hammershank is trimmed. I then 
put the sliding sleeve back into the plug and reinstall the sleeve 
assembly, extend the sliding sleeve to its fullest (actually it could 
be anywhere--we're not indexing off it but off the plug rim--but we 
are using its length to lash the gage stick against). When the gage 
is fastened to the sleeve with is top end just even with the plug 
rim, the bottom of the gage will approach the surface of the plate, 
and as soon as that distance equals zero, the piston rod will be 
prevented from retracting the amount which it needs to trigger. The 
beauty of this system is that, unlike my old system where the the rod 
was slaved to the punch and could yet pounded into the plate as the 
tuning pin was driven, here the contact between the plate and the 
gage results directly in the nailer being prevented from driving.

The 3/4 hour R&D time(including going to the hardware store for wider 
hose clamps) was well worth it. A picture is worth a thousand words.

Bill Ballard RPT
NH Chapter, P.T.G.

"Schumann wrote in spurts, composing an incredible amount, then 
writing nothing for a stretch. While Clara was away from home giving 
concerts, Schumann was completely unable to compose."
     ...........A "Junior Scholastic" profile of Robert Schumann. 
(Say, if Robert was unable to get any composing done when he was on 
kid duty, how come his wife had no problem preparing her programs 
while looking after the six kids in that household?)
+++++++++++++++++++++