Hammer weight

[Don_Mannino@yca.ccmail.compuserve.com]

     Vince wrote:

     >>Don, how will the speed of the hammer increase by merely decreasing
     the knuckle size?  It doesn't do anything to change the leverage.<<


     Draw and arc, centered on the hammer shank center pin and intersecting
     the jack / knuckle contact point. Now reduce the knuckle size 2mm and
     draw another arc.  The radius will have decreased a little with the
     smaller knuckle.  This is where the leverage change comes from.

     >>I also don't see where the friction increases here.  I've decreased
     knuckle size and had a decrease in touchweight.<<

     I've experienced friction going both ways when altering the knuckle.
     You're right, though; it usually _will_ go down because most actions
     today are set up with the letoff taking place significantly below the
     spread line. Making the knuckle size smaller in these actions moves
     the letoff closer to the spread line, so decreases friction.

     In an action where the letoff takes place pretty close to the spread
     line already, the friction can go up a little when changing to a
     smaller knuckle.

     Also, the reduced contact area between the knuckle and the rep.
     lever/jack top caused by the smaller knuckle will reduce the knuckle
     to whippen friction.  Those actions I've worked on where the friction
     went up had good knuckles of 11-12mm diameter, and I reduced them to a
     little under 10mm using the same skin (peel them back, sand the cores,
     reglue the skin).  The increase in friction (down-up/2) was 1 to 3
     grams.

     I was explaining this by considering that the leverage change will cause
     a slight increase in friction at the whippen / capstan contact and at
     the knuckle / jack contact. This is due to increased force being
     required to move the hammer, increasing the friction between parts.
     Perhaps I shouldn't bother considering that as a general rule, because
     the friction change is small and is usually more than counteracted by
     the improved letoff timing (closer to the spread line).

     Thanks for your comments.

     Don_Mannino@yca.ccmail.compuserve.com