Bridge Notching Trouble-- Terry Farrells question

[Isaac OLEG]

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Never used the mthod myself but I've seen notchning done with a sanding
machine (small band , called electric file)

I believe the chisel I use is a carver's chisel, it is convex on its twoo
sides the same amount .

For the vertical side of the notch I use a large chisel modified to follow
the curve, a rap of this one first, and the rounded chisel shave the notch
at the speed I want, because the curved chisel allow to do very small shaves
ar bigger one depending of the angle it is driven.

All these perfecly cutting (with a water stone and japanese stones for
finishing) .
I believe you have Arkansas stones in the USA, or are they coming from
another place on earth ?

I like the Japanese water stones but a truing block is necessary because
they are generally soft.

Isaac O.



  -----Message d'origine-----
  De : pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]De la
part de Erwinspiano@aol.com
  Envoye : vendredi 8 novembre 2002 05:30
  A : mfarrel2@tampabay.rr.com; pianotech@ptg.org
  Objet : Re: Bridge Notching Trouble-- Terry Farrells question


  In a message dated 11/4/2002 4:28:00 AM Pacific Standard Time,
mfarrel2@tampabay.rr.com writes:



    Subj:Bridge Notching Trouble
    Date:11/4/2002 4:28:00 AM Pacific Standard Time
    From:mfarrel2@tampabay.rr.com
    Reply-to:pianotech@ptg.org
    To:pianotech@ptg.org
    Sent from the Internet


           Terry wrote
    I'll have some bridge notching coming up in a while. I have always had
some trouble in the past keeping the notched top edge sharp. By this I mean
I line the chisel up in the middle of the bridge pin holes, start my
downward stroke (I try to do a bit of a curve so that the top edge is a
large angle - not vertical, but more vertical than horizontal), but then
after going downward the first tiny bit (maybe one millimeter or so), I need
to angle the chisel more toward the horizontal. At that point I find my
chisel riding on the top bridge-pin-line edge that I just cut so nice and
cleanly. The riding motion tends to round off the nice top edge that you
want to be ever-so sharp. How not to do that? I can see that cutting a
straight angle would fix that problem, but I've always thought that the
steeper you can make the top edge, the better the termination (assuming you
don't undermine the bridge pin). I think Fazioli puts a vertical drop on
their bridges. Those pianos sound OK to ! !
    me.



            Hey Terry


       I thought about your question again today as I was busily notching.
Everybody has there own way of doing this and heres mine. I noticed that if
you look really closely at a side view of a really nicely notched bridge
there is a really nice scoop look moving down and away from the pins
starting at the point the where the strings are bisected.
        II have found of course really sharp chisels are  required to carve
these notches. I'm sure that's no mystery to you. The key for me was two
things. I use a Freud 1 inch chisel with the back slightly rounded and I use
it upside down for the final cut. I hog out most of the wood from the notch
with an offset Japanese dovetail chisel and then on my last cut or two with
the Freud I bisect the pin line and with a smooth but quick motion push
forward and down the back of handle at the same time. I found that moving to
slow is less accurate and successful but faster requires the confidence to
just go for it. Does that make sense?


        If every thing is working well I can hold the bridge up at eye level
and see if our notched are imitating the
    same kind of beautiful swoop those guys did at the factory. The tough
thing for us is that we don't do this everyday like the good ole boys did so
we kind of have to mentally think it through each time.  It used to take me
several hours to notch a bridge. I've got down to bout hour and half. I find
that if I can do one a month or so I stay sharper than if I've had a 3 month
hiatus. It's all about practice and frequency like the rest of our business.
Hope that helps.
                    Dale Erwin




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