shank strike weights

[Jon Page]

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>  What is the benefit or what <is> the noticeable difference of measuring
>the knuckle, besides making the let off buttons nice and even and look good?

I first started measuring knuckle and shank thickness because of what I would
call a poorly installed set of knuckles and was surprised to find 
such a wide disparity. Measuring the thickness of many shanks proved 
to have negligible differences so the differences were in the 
exactness of pressing the knuckle in. I measure from the top
of the shank to the bottom of the knuckle.
Last year I posted about a knuckle caul press for this concern.

Subsequent sets measured to have differences between .5 and 1 mm (.020 - .040")
within the set. I maintain a window of .25 mm (.010"), that's +/- 
.005" (.125 mm) from
the average overall shank/knuckle height. I place the bulk (average) 
of the shanks
in the center and the +/-'s at the extremes. A more level let off 
button line was just an interesting result.

Action geometry is affected by the size of the knuckle so anything 
one can do to
bring uniformity benefits the action.  Priority for shank selection 
is matching shank SW
to hammer weight with knuckle height second.

Ultimately the best scenario, inertially speaking, would be to 
graduate the weight of the hammer heads themselves and group 
same-weight/knuckle height shanks. But most hammer sets are
so erratic in individual weights that it takes invasive procedures to 
have them comply.

Matching shank SW to hammer weight has proven to require minimal 
intervention for
a smooth SW curve.

First, I bore and taper the hammers.
Weight them and plot them on a graph.
Select shanks accordingly and install them on the rail. (# on 
underside next to knuckle)
Hang hammers.
Remove h/s/f from the rail.
Cut the protruding shank off with a band saw and rough cut an arc.
Set up fence to trim tails on disk sander to even length.
Arc tails.
Weigh SW and plot on chart
Adjust SW
Install h/s/f on rail.

I sounds like a lot of work but it goes fast. I like to arc the tails 
after hanging the hammers
to produce a nice finished edge. I also ease the edges (sides and 
bottom) of the tail molding
to remove the sharp corners with a file.

-- 

Regards,

Jon Page
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