Accu-just Hitch pins - any time, any place!

[pianos@telusplanet.net]

Hi Del, 

	The piano in question is a Baldwin scale "E", which is pretty 
similar in scale to the "R" grand. According to my Baldwin shop 
manual, Baldwin lists scales for Accu-just and Accu-set hitch pin 
pianos, and scales for traditional pianos. The numbers for the E 
scale and non-AJ R scale are fairly close, the E scale incorporates 
more 1/2 size wire changes in the lower tenor over more unisons. 
The R scale for both types of hitch pin arrangement are virtually 
identical, with only 3 deviations in number of unisons for identical 
wire sizes throughout. I don't think that wire size has much to do 
with determining what type of hitch pin layout is used. Nor do I 
think that speaking lengths or bridge placement varies greatly 
between the above models. The plate structure isn't greatly different 
between these pianos either. So is hitch pin layout is the critical 
factor in deciding whether or not a piano can withstand retrofitting 
to adjustable-type hitch pins? 

I quickly took some micrometer readings from a new R grand with 
AJ hitch pins on the sales floor and a Wurlitzer (Samick) C173 5'8" 
with a traditional HP layout for comparison:

Average hitch pin diameter: 

Baldwin R	= .223"							 
Wurlitzer C173 = .168"

Average hitch pin spacing: 

Baldwin R = Staggered .3 - .5" apart, some non-staggered, 
alternating distances apart, pins no closer than 1" from lip of plate

Wurlitzer C173  =  .35" apart in treble in even sections of 12 - 16 
pins in a curving row, with a .75" set back on the next row.
Bass alternately staggered .5" apart and .5" offset 
Pins no closer than 1.75" from lip of plate 	

Plate thickness (at lip of plate, adjacent to bridge)

Baldwin R : treble .362"
			mid-tenor   .423"
			bottom tenor .366"

Wurlitzer C173  treble: .4"
				mid-tenor .415"
				bottom tenor .435"

Hitch Pin Height

Baldwin R:  .467- .545" throughout

Wurlitzer C173  .415 - .423" throughout (holes drilled straight and 
pins bent back. Pin height is total length of pin, not actual height 
off of plate)
			
Height of string above plate

Baldwin R
top treble .313" to .378"
treble .315" to .202"
tenor  .110" to .271"
bass  .186" to .229"			
 
The top section strings are definitely above the 2/3 mark on the 
hitch pins, the rest of the strings are below the 1/3 mark. Angle to 
the bridge is minimal.

Wurlitzer C173
flush to plate at hitch pin, however the string angles steeply up and 
over an aliquot bar on the plate and continues to the bridge. The 
angle of deflection of the string leaving the hitch pin is significantly 
sharper than the string leaving the Baldwin hitch pin. 

So what the heck do all these numbers mean?

1) Baldwin hitch pins are not significantly bigger than other hitch 
pins   .223" compared to .168". You can buy smaller diameter pins 
than the type Baldwin uses if you need to.

2) The plate thickness and hitch pin spacing are thinner and closer 
on the  R grand than on the Wurlitzer. Does that mean that the 
Wurlitzer would be a good candidate for adjustable pins? The holes 
are drilled straight and spaced farther apart than the Baldwin. 

What would influence you to replace a set of 'standard' hitch pins 
with adjustable, if these plate and hole measurements 'seemed' to 
meet or exceed what is currently used on new manufactured 
pianos, such as Baldwin or Charles R. Walter?

Questions, questions...

Rob Kiddell RPT
atonal@telusplanet.net