Hammer maker's ignorance

[isaacah]

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Hammer maker's ignorance.



I've been making hammers since 1980 but what I don't know about felt =
making could fill a large volume. What I do know may interest some of =
you so here it is.



Felt is made of wool, so far so good. There are a number of wools that =
could and have been used for piano hammer making. Wool is used because, =
presumably it is a medium that can be packed into a mass that is both =
hard and resilient at one and the same time. I suspect that the grid =
like character of felted wool as well as its 'scratchy' feel have more =
than a little to do with its potential for tone producing. Wool, like =
wine, is affected by the amounts of rainfall and therefore by the =
nutrients in the grasses eaten by the sheep, so that wool has what wine =
lovers call 'vintages' (woolages?). These factors used to be important =
in matching wool varieties for the blends of hammer felt sheets back =
when pianos were - at least in my opinion - better, on the whole, than =
they are today.=20



Hammer felt sheets are constructed in two ways: felting and pressing, =
both methods are used but in different proportions to one another, =
depending on the hammer maker's requirements and on the abilities of the =
felt maker.=20



Felting is the process of working the wool fibers by mechanical fingers =
so that they interlock to form a felted mass that is three dimentional; =
the fibers are oriented in every direction imaginable.



Pressing is just that, pressing the fibers to cause them to interlock =
having laid them out, more or less, in a given direction. The resulting =
mat is thin (about .0625" or so). The number of thin mats required to =
make up a given weight of hammer felt sheets is tacked together and the =
felt sheet is layered. Since the entire hammer felt sheet tapers from =
bass to treble and the thickness of each thin mat is constant, it =
follows that each mat is tapered to end somewhere along the bass/treble =
axis to permit the whole sheet to maintain its overall taper.



The relative merits of tone producing capacities of the two types of =
felt: layered (pressed) felt versus three dimentional (felted) felt can =
be easily deduced from the amounts of voicing required for each both =
during installation and repeat voicings due to tonal stability or its =
absence later, during the life span of the hammers.=20



It seems clear that layered felt hammers can barely perform without =
massive infusions of hardener to enable the first stage of tone =
production - the impact, occasioning the inescapable need for a great =
deal of needling to tonally adjust the second stage of tone production - =
the rebound.



My personal dislike and distrust of this system emanates from the =
implied loss of control for the technician. Can you make a hammer made =
from layered felt work? Of course you can but you're never in control. =
When you juice a hammer you never know how much the tone will change =
until the thinners have dried and listening becomes possible. Since, =
having juiced the hammers, you now need to needle the excessive =
brightness out you've lost control over the tonal stability of the =
hammers. This is so because the tone produced by the hammers you've =
spent so much time and effort voicing is the result not so much of the =
makeup of the felt and the pressing of the hammers but of your actions - =
juicing and needling.=20



>From my experience working with the materials I work with - felt, wood, =
steel and copper wires - I know that the more control I have over these =
materials during a given process - the better, the more predictable the =
tonal results over time. I endeavor to pass on maximum control to the =
technicians using my products so they, in turn, can more easily obtain =
the desired tonal results.



I shall discuss three d (felted) felt next time.=20



Thanks for reading this,



Ari Isaac.=20



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