I seem to have lost the correct e-mail address for PTG exam-related
issues, so I hope the right person (Israel Stein) gets this:
Re: the Young Chang 3-note vertical action model:
When I ordered one for our chapter from the Home Office, someone there
said it shouldn't require any alteration or modification to make it
exam-worthy.
I disagree. On the model I received,
1) All the screws on the back of the vertical "mounting moard" needed
tightening.
2) On the key stop rail, the felt-and-wood shims were way too thick.
Even at the highest reasonable key height (balance rail pins almost
"buried"), there was still a huge gap between the keytops and the key stop
rail felt. So I replaced them with thinner shims.
Also, traditionally, most removable parts of a piano case have
clearance holes through the removable part, i.e., they're not threaded --
only the pilot hole into which the screw goes is threaded. This changed
in recent decades where manufacturers started using screws that are threaded
all the way up to the head, and which they can run in with power drivers
without first drilling a pilot hole. I call them "drywall screws," but I
think there's another name.
Anyhow, the examinee should not have to waste time unnecessarily just
screwing in this type of screw. That's not what s/he's being tested on,
even though real pianos have them. So I think the key stop rail and the
"key bed" should have 11/64" clearance holes drilled through them. Also
widen the pilot holes a bit or put some VJ lube into the holes with a
toothpick so the screws run in and out easier.
3) As for the key slip, it's a bit too tall. If the examinee sets a
low key height, the key front is almost rectangular rather than square, as
it should be. I feel the key slip can stand to lose 1/16" to 1/8" off the
bottom (a disk sander does it real quick). As with the key stop rail,
drill 11/64" clearance holes through the "key bed" (bottom mounting board)
to make it easier to take on and off.
4) Remove the jack stop rail. (This was specified in the exam book for
the old Kimball 3-note model we used to use).
5) Discard the leather washers for the action bolt nuts. They're
going to get lost anyhow, and they don't really do anything except
interfere, get caught in the threads, and waste time.
6) The spoons had to be driven farther into the wippens (barely 1/16")
to keep from scraping the damper lift rod when the pedal is not connected.
Yes, you can just lift the rod, and they don't scrape, but I felt that
spoons could be bent or a wippen be split too easily.
7) Remove the hammer rail rest pads so that setting of hammer blow
distance won't be automatic.
Both the hammer rail and the action brackets are metal, however,
making it hard for the examinee to glue felts for setting hammer blow
distance. I roughed-up the surface the felts glue to on the action brackets
and epoxied a thin wafer of wood there. The examinees are supposed to use
Elmer's glue, anyhow, and the wood allows them to do this and not have to
attempt gluing felt to metal with hard-to-remove glues. We have to take
these felts back off for the next examinee.
8) The hammer butts on our model were pinned too loosely (over 8
swings), so they had to be re-pinned.
9) The string "targets" for the supposedly 3-string unisons are single
guitar frets mounted vertically, and look like single strings, even though
the hammers are not angled and the dampers have flat damper felt (as for
3-string unisons). Well, sighted technicians figure out that the fret
represents the center of a 3-string unison, but it could possibly be
confusing to a sightless technician, who finds things by feel. I haven't
thought of an easy way yet to make it feel like a three-string unison.
10) There was no positive stop for the pedals because the pedals are
hollow underneath (an inverted U) and the legs, or sides of the inverted U
barely catch the edges of the too-squishy felt that was supposed to stop the
downward travel of the pedal. The felt wasn't wide enough, either. In
other words there was no easily discernable spot where the pedal hit bottom.
It depended how hard you pushed it down -- no good for scoring. So,
disassemble the pedal mounting far enough to be able to epoxy small blocks
of wood or other hard material into the underside of the pedal where it
contacts its stop felt. I think I used little chunks of popsicle stick.
Make these blocks even with the bottom of the pedal sides. This provides a
flat surface that hits the pedal stop, like the old cast iron, rectangular
pedal shanks. Then remove the too-squishy felt and replace it with hammer
skiving felt of appropriate thickness for typical pedal travel.
As for regulating the thing, the blue exam books have two places (page
19 and page 31) where the optimum blow distance and key dip are to be
recorded (after being determined by an RPT who is
supposed to "super-regulate" the model and determine these two parameters).
I determined that the model could have a small RANGE of key height (from
62 to 66 mm, or roughly 2 1/2" to 2 11/16"), with dip at a hair over 3/8",
and regulate OK to pass the exam. I don't see why optimum dip is left to be
determined by the RPT "super-regulaters," when 3/8", or just a hair over, is
considered standard. I don't think any specs at all should be given the
examinee. They should determine key height from case parts and key pins,
set key dip to what's considered standard, then set their blow to get it to
regulate properly.
Is it OK to put a key height RANGE and a key dip RANGE in those blanks?
Just for your info., in the official Young Chang Service Guide,
Specifications for key height are given as 62mm (2 7/16 ") for
models U-107, 109, and 111; and 64.5 mm (2 17/32")for
the U-121 and 131.
Specifications for hammer blow are given as 45 mm (just over 1 3/4")
for the 107, 109, and 111; and 47 mm (just under 1 7/8") for
the 121 and 131.
Key dip is given as 10.2 mm, or .401" (which is just under 13/32",
but more than 3/8").
--David Nereson, RPT and chief examiner, Denver Chapter
This PTG archive page provided courtesy of Moy Piano Service, LLC