Hammers Head

[Newton Hunt]

Hi Rogerio,

The best bore distance is string height minus hammer center height
and add about 1 mm for wear and filing.  2 mm may be too much.

The angles of the bore is measured by measuring the angle of the
strings to the stretcher (front edge of the case, pinblock or
plate).  The hammers cannot be bored more than 15 degree without
running into passing problems.  Usually by the tenor section the
bore angle is zero.  Measure the angle of the bass strings divide
by 2 and bore at that angle.  Bass hammers have even less room to
pass each other than they do in the middle.

Strike line is determined by ear at 88 or 87 by putting a hammer on
the shank and moving the action in and out while strike the key
quickly and hard to find the loudest point.  Move the hammer along
the shank until the best location is found while the action is in
it's original factory position.  Do this at the top and bottom of
the top section and you will have a consensus for strike line
location.

If you are having trouble determining the best location space the
shank so the hammer is only hitting two strings and repeat the
above.

If the hammer bore is a bit loose you can moisten the inside of the
hole with saliva or water for a tighter fit.

Now you have samples set for gluing.

Shank to molding angle may not be 90 degrees.  You should take
sample hammers and see if there is sufficient space for a 90 angle
or it is needs to be different.  Best way to decide is to draw a
line along the center line of the hammer and molding and determine
if that line is 90 degrees to the string when it is help up to the
strings.  Mason & Hamilins require an inward angle of 89 degrees
and many European pianos did not use 90 degrees like Bechstein.

		Newton