touch weight

[Newton Hunt]

Ok folks, David has come out with better and important information. 
Heed it well.

		Newton

"David C. Stanwood" wrote:
> 
> Newton,
> 
> Some comments on your recent post:
> 
> >Would measuring the weights at three or for velocities give an idea of
> >inertia?  Inertia is a major consideration of drive head arms so you
> >may have some information or ideas in this area already.
> 
> An increasing number of technicians find that they can control inertia
> by choosing hammer weights that are compatable with given leverage ratios.
> 
> This means looking at Hammer weights and Shank Strike Weights before the
> hammers are hung, or Strike Weights if measuring after the hammers are
> hung.  The trick is to know what leverage components work with  what hammer
> weights.  This is basic engineering 101.  If the rock is  too heavy get a
> lighter rock or a stronger arm or both!  High ratio actions like 1:7 are
> totally intolerent of hammer heaviness.  1:5 actions can handle the heaviest
> hammers made.  Then there is all the stuff in between.
> 
> The most common mistake that techs make is to use a knuckle that is 15.5mm
> out on the shank as the original parts were, then using a heavier modern
> weight hammer.  For Today's hammers the most succesful part is the Hamburg
> style shank with the knuckle mounted 17mm out from the hammer center.
> 
> Leverage is made more complicated by the fact that key ratios vary from one
> Steinway to another.  I strongly recommend that any tech who is replacing
> parts, learn how to use a standardized method of measuring key weight ratios
> or key distance ratios and keeping notes on what key ratio works best with
> which
> part and hammer weight level.
> 
> Lack of attention to these details lends an aspect of "rolling the Dice"
> to our work.  Take measurements and keep a notebook!!!!!
> 
> >The current practice is to remove the front most key weight then place
> >a 20 gram weight on the key then set the down weight by moving weights
> >back and forth on the key then using differing weights determining how
> >much weight the key will lift, this gives the friction of the key.
> >Then use a set of up and down weights predetermined by friction and
> >desired balance weight and cut a weight down until it will achieve the
> >goal by placing it into the vacated hole.
> 
> Don't forget to always cross check the down weight.  As a rule of thumb,
> if it's above 50 grams check friction.
> 
> David Stanwood