Hammer Weight vrs Friction

[Jon Page]

At 12:30 AM 10/19/98 -0400, you wrote:
>Jon,
>
>I'm glad you posted these numbers for the "B".  I have had several "B's"
>with very similar results.  Unfortunately, a 58 dw for some players is way
>too high, but due to the problems of these actions there are only the
>alternatives in which you posted.  My last two "B's" feel spongy and I'm
>just not happy with them.  The key element here (using the 17mm shank) is
>the key ratio.  A 0.53 is a higher number than optimum.  I think a 0.49
>would be much better eliminating the use of yet more key lead....which can
>only result in increased sluggishness.  The Strike Weight Ratio at 6.15 is a
>vast improvement and maybe your action feels pretty good.  I'm mystified
>though when you get around a 6.1 or 6.3 SWR and the action still feels
yucky.  

I didn't say the action felt bad. It feels better than it did, just not
bad. But can
be improved. The Ratio (capstan placement) of .53 allows for the jack to
clear the knuckle and be in close proximity at the end of the keystroke.
I have seen Ratios below .50 and they did not sufficiently move the wippen
through enough motion to get the jack to clear. I had to move them back 

>David's (Stanwood) chart depicting medium range numbers I think are a little
>high.  Using the Strike Wt. Smart Chart, I've found in just about every
>action that the hammers need thinning down to the lower numbers on the
>chart, respective to the "range"...otherwise the action is still too heavy
>and not nearly responsive.  Bob Marinelli was telling me of his use of the
>West Systems epoxy, filling the capstan holes and moving the caps enough to
>still catch the whippen heel (without the whole shabang of cutting them and
>regluing).  

I have placed SW's in the low zone. Not all hammers can get down that low
without losing width at the strike surface or looking anarexic. 

>I've moved capstans before and cut whip heels on some bizzare actions for
>Ampico players when retrofitting.  I guess consistently the "B's" need the
>most work....I'm thinking of getting that action back in the shop and
>improving the cap line...then should be able to remove some lead.

One B needs the capstan to move forwards about 3'8", this is beyond the heel.

>Just another note:  I've had an impossible time getting consistent SWR's
>throughout the keyboard...many factors cause this change (felt variation,
>pinning, etc...from note to note), but I don't get too hung up on it...use
>it as a "National Average" so to speak.

My theory: As long as there are minute differences in KR and FW (SW
graduation presumed), the  SR's will not be plotted on a line. However,
if the FW were graduated and KR straightened out; the use of wippen
assist springs to target the BW will place the SR's on a curve.

Short of that, adjusting FW to target BW is satisfactory (considering the
amount of lead already present).

>To sum up:  I think if the key ratio is above 0.50, acceptable end results
>are more difficult to acheive than if it were lower.  

Perhaps below .50 with a 15.5mm knuckle radius. I'm not an authority on
this but I have found best results in the low .50's.   The Sohmer in the shop
now has an even (that's consistant) KR of .59.  (It is rare to find this
consistency.
Usually I find at best that the naturals are one KR and the sharps are
another).
That's high, but no room on the cushion to move the capstans forwards and 
the budget of the customer is maxed-out.  But it plays satisfactoraly.

So, on to the next . . .

Jon Page
Harwich Port, Cape Cod, Mass. (jpage@capecod.net)
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