Hitch Pin Plate Drilling

[Tom Servinsky]

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Speaking of hitch pins, does anyone know if Baldwin is still selling the =
accu-just hitch pins. I have client with a Baldwin SD10 with  a =
defective set of accu-just hitch pins which are breaking off one at a =
time. So far more than a dozen have snapped in the last 6 months.. Del =
had mentioned that Baldwin had a bad run of accu-just hitch pins in the =
70's ( when this piano was made).=20
Tom Servinsky
  ----- Original Message -----=20
  From: Farrell=20
  To: Pianotech=20
  Sent: Friday, June 24, 2005 7:08 PM
  Subject: Re: Hitch Pin Plate Drilling


  That's just what I was going to ask you - what kind of pin are you =
using? For traditional pins, I have used a drill bit the same diameter =
as the pin and found the fit to be nice and tight. If yours are loose, I =
would suspect a bent drill bit or somesuch. Are you doing the drilling =
with a drill press with a good chuck? Have you measured runout? For =
vertical hitches I use stainless steel spring pins. If I remember =
correctly (it's been a while since I drilled them) you use the same size =
drill bit as the pin. The pin is slightly expanded and when you pound it =
in the hole, it will compress a little bit for a very nice snug fit.

  If you are hand drilling, perhaps that is your source for the enlarged =
holes. I'm sure you could successfull epoxy a loose one in place. I =
would recommend using West System resin thickened with their #404 =
High-Density filler - that pin won't go anywhere.

  Terry Farrell

    Never mind.  Didn't read carefully enough.   I see that your drilled =
the same size as the pin.  Does that work out?  When I've tried to drill =
out for new pins it seems that the hole ends up slightly bigger than the =
drill size and the pin is often slightly loose.  How should it be?  =
Should one be tapping them into a snug fit or do you worry about =
stressing the cast iron if they are too tight.  Should they be secured =
with epoxy?  What's the approach?



    What type of hitch pin did you use and what drill bit size did you =
use relative to the diameter of the pin?

    David Love
    davidlovepianos@comcast.net=20

    =20

    Recently faced the same problem on my first and only vertical hitch =
pin conversion.  Bass bichord hitch pins alternated fore and aft, but =
still not enough space to make me feel comfortable picking a new =
location.   Old pins were reasonable tight, so I left them in place, =
ground them flush with the top of the plate, and drilled the new holes =
down through the center of the originals.  3/16 diameter (larger than =
the originals at .156) and 9/16 deep (considerably deeper than =
originals).  Thus the top and the bottom of the new hole are in fresh =
cast iron.    Needed the drill press because the original pins were =
harder than surrounding cast iron - couldn't push the drill in by hand.  =
 See photo.  New pins will be 3/16 x 1", with 7/16" exposed.  If I set =
the height of the new bass bridge cap correctly, the loops will rest =
about 1/8 above the plate. =20

    =20

    Mike

    =20

    =20

      I'm about to drill a plate for vertical hitch pins. On the few =
plate I've done this to, I've always had enough fore-and-aft room in the =
hitch pin area to place the new hitch pin at a desirable location, and =
not be real close to the original hitch pin. Unfortunately, on the plate =
I need to drill, the hitch pin area is relatively narrow and I can't go =
very far fore or aft with the new location. I can only assume that the =
original steel pin is a lot harder than the cast iron and I must avoid =
hitting it. Agree? Any general advice on placing the new hitch pins in a =
situation like this from those who have crossed this bridge (or rather =
hitch pin area) before?


      I could go immediately aft of the originals, but that would put =
all pins in one line - although the originals held up for 100 years in =
that array. Should I just do that and not worry about it?

      =20

      Terry Farrell

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