hammer thickness trimming jig, found mine!

[Greg Newell]

Will,
	That was VERY kind of you to have gone to all that trouble. When I
have more time I will have to sit down and re-read this and try to build
myself one. Thanks very much!

Greg Newell
Greg's Piano Forté
www.gregspianoforte.com
216-226-3791 (office)
216-470-8634 (mobile)


-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Will Truitt
Sent: Tuesday, August 26, 2008 8:05 PM
To: 'Pianotech List'
Subject: RE: hammer thickness trimming jig, found mine!

Hi Greg and Jon:

I promised yesterday in my dialog with Jon Page that I would search through
the catacombs of my shop for a jig I built some years ago to taper a set of
already hung hammers.  I found it today, and brought it home from the shop.
Please forgive me for not offering you a photograph, I am one of those
Luddites who still does not own a digital camera.

I've been tapering my hammers for twenty plus years and have built and gone
through 4 generations of jigs, each a little better than the last.  I was
pretty happy with the last one (still using it), so when I needed to build a
jig to taper a set of hung hammers, I modified that design in small ways to
adapt it to tapering a hung set.  The idea for the hold down came from
someone else, I just can't remember who so that I can credit them.  

The jig is made primarily of Ultra High Molecular Density Polyethylene.
This material is self lubricating, dimensionally stable, and can be drilled,
sawn, and otherwise shaped fairly easily.  I made mine from 1/2 inch and 1
inch sheets.  The base of it attaches to a mitre slider that fits in the
mitre channel on your table saw.  Some of the aftermarket sliders are
slightly adjustable for width so as to eliminate side play.  

The base of the jig is about 8" by 8".  I routed a 4" wide and 1/2" deep
slot across the middle of the base, on which sits a 1/2" thick sheet of UHMD
polyethylene, which has a slot cut in the middle of it through which a
machine bolt (which head is countersunk into the base) comes through.  It
slides back and forth across the base, is micro-adjustable by a machine
screw bearing against it at the end, and is locked in place by a wing nut.
This controls how much the blade will cut off the side of the hammer.

On top of that is another sheet of round plastic that serves as a turntable.
That pivots around another bolt, is micro-adjustable, and locks in place by
another wing nut.  This controls the angle of the cut.  On top of the
turntable sits a 1" thick vertical sidewall that the hammer will bear
against.  It is tapered in height from about 4" at the end towards the saw
blade to about 1" high at the tail end.  There is a rounded recess that the
hammer shank can fit through when the angle of the hammer bore requires it.
At the tail end is an adjustable end stop, to accommodate the varying tail
lengths that different hammers will have.

And now for the meat and potatoes of this design - that which makes it a
safe and fast way to taper hung sets of hammers.  An inch or so in from the
tall end of the vertical sidewall, and above the highest point that the
blade will need to reach for the fattest bass hammers, you will drill a hole
through which to run a bolt threaded at the end but not at the middle.  This
bolt is recessed into the hold down arm.  A set screw locks the arm in place
on the hold down arm.  On the other side of the vertical sidewall is another
arm, which is spaced in position with a bolt and washer on each side, and a
set screw.  You can make this arm whatever shape and length you wish.  When
you pull up on it, the hold down arm is pulled down onto the hammer and
holds it quite securely against the fence after you position it.  You
continue pulling down on this handle through the cut as you push the jig
towards the blade with the other.  

My hold down arm is shaped somewhat like the inside cove of a hammer.  This
allows it to accommodate the varying shapes and thicknesses of the hammers.
I have 80 grit paper lining it to give a greater frictional contact with the
felt of the hammer.  Greg you will likely want to experiment with exactly
what shape you will want this to be.  

You will have to make two of these jigs, one for each side of the hammer
that you taper, and they will not be set at the same angles.  You will have
to experiment with the depth and angle settings on both jigs a fair amount
before you are tapering the same amount and the same angle on both sides.
Because this part is a bit of a hassle to set up, I take the jig off the
table saw, bring it to the drill press, and drill a 90 degree hole into
which I insert a balance rail pin to serve as an index.  That hole is
drilled through the turntable, through the cross slide, and into the base.
This way one pin locks in all settings. 

You can use this jig for both hung and unhung sets of hammers. Very fast,
too.  Zoop, zoop, in and out.  

Jon, I respectfully submit that this jig is much safer than your method.  I
can exert far more pressure than I need with the lever arm, and the hold
down arm is bearing directly on the hammer very close to the blade.  The
hand that is levering the hold down arm is on the other side of the vertical
wall, and I can locate it along the length of the pivot well away from the
blade.  

There are variations on the theme for table saw hammer tapering jigs, and
likely this protocol could be adapted to a great many of them.  

Someone else may have a simpler and better way of doing this, and I am all
ears for that too.  Until then, I can vouch that this method works very
well, is fast, and very safe.  It protects me from my own worse impulses.
If there is operator error, the hammer suffers, not me.  

I hope I have stated things clearly and that such a jig can be useful to
you, Greg.  

Regards,

Will Truitt

 

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Greg Newell
Sent: Sunday, August 24, 2008 10:48 AM
To: 'Pianotech List'; 'College and University Technicians'
Subject: hammer thickness trimming jig

Greetings kind folk,
	I’m hoping that someone out there in cyber land can help me today. I
have the task of thickness trimming on some prehung hammers from S&S. The
hammers came too thick for the vintage grand I’m working on as there is not
sufficient clearance to allow reliable individual hammer movement.
Ordinarily I would do this before hanging hammers but since these are
pre-hung 
. well I’m a bit stuck. Does anyone know of a jig that could be
built that would accommodate trimming with the shanks on? The archives seem
to point to something from Roger Jolly but the posts I read were not
conclusive that one exists. Help?!?

Greg Newell
Greg's Piano Forté
www.gregspianoforte.com
216-226-3791 (office)
216-470-8634 (mobile)