popsicle stick engineering

[Jon Page]

A good place to start when chasing down the optimal capstan location 
is with the Magic Line.

There are three ways to support the key at half blow.
Set a tri-square to the h/b measurement and prop it vertically with a 
spring clamp,
place a weight on the front of the key and block the hammer on the 
square. I usually do this.
Place a shim (~9/16 drill bit) under the front of the key and place weight.
But a way I just thought of which may be easiest of all is to insert 
a wedge (mute?)
under the back of the key to raise the hammer to h/b. I'll definitely 
try this next time.

Set h/b, run a thread for the ML and place a mark at the wippen 
cushion at the intersection.
Draw a line on the side of the wippen perpendicular to the heel 
profile at that mark.
Straight heels are easy because you only need to hold a ruler 
parallel to the repetition
support post.

With the assembly blocked at h/b, extend that line onto the side of 
the key. That is the bore
angle and first check for capstan location. For argument's sake, one 
could have the capstan
perpendicular to the heel at let-off, I haven't tried it but it 
sounds logical. I do this check
on C1 and B7 because I can remove the adjacent keys and wippens for 
easy access,
a few in the center if you want too.

SInce you've already determined your bore length and selected the 
knuckle radius
and key dip, place your temp capstan at this location and depress the 
key, is the jack
clearance optimal? If the jack is buried into the stop felt the 
capstan has to move forwards.
If not enough clearance, move the capstan back (not every balance 
rail is in the optimal
position either). Locate the capstan for optimal regulation: 
sufficient jack clearance effecting
minimal after touch. Think of it as the wippen being moved through a 
required distance
and how where along the levers the lift is provided regulates that distance.
Bore the holes at the derived angle.

Many actions I've improved regulation by addressing the capstan angle 
and not move
it forwards or backwards, the angle corrected the distance the wippen 
was propelled.

Think of it in terms of the arc of the travel, as the capstan moves 
further from the
balance rail, it's arc increases. It also moves closer to the wippen 
fulcrum which
has a greater result at the front of the wippen. Because as the lift 
provided to the
wippen moves closer to its fulcrum the end moves a greater distance. Of course,
conversely, moving the capstan forwards reduces the travel at the 
front of the wippen.

But you need to bear in mind present touchweight. Increasing touchweight by
moving the capstan away from the balance rail for regulation may be 
counter productive.

I get the feeling I'm about to get into a circular predicament.
-- 

Regards,

Jon Page