seeking wood screws

[Dean May]

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It's a throwback to my days as a design engineer. It is bad practice to
place any kind of stress concentrator against cast iron. The washer is a
little insurance to distribute the load, though ideally it should be
hardened to maximize its effectiveness.

Thanks for the tip on the hole.

Dean
  -----Original Message-----
  From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]On
Behalf Of Terry
  Sent: Saturday, January 08, 2005 11:34 AM
  To: Pianotech
  Subject: Re: seeking wood screws


  Why do you put a washer on top of the up-side-down lock nut that goes on
the backside of the plate - assuming of course that the nut has enough
horizontal surface area to mate with the plate (and not want to fall through
the hole)? I would just be afraid of a potential rattle/buzz if one of the
assemblies got a little loose (I realize that none should be). I just
haven't found that to be needed. I do put a washer on the top though - but
mostly to protect the plate finish while tightening the acorn nut on top.

  5/16-inch hole gives me a nice very snug fit.

  Terry Farrell

    All this talk of screw sources has had me browsing some of these sites.
Very cool. I've always tried to maintain an organized supply of various
screw types and sizes which has been a huge asset. But it is not always easy
to get big boxes of the sizes you want any more. Most places only sell the
little 15 piece plastic packages (very expensive way to buy screws).

    Anyway, I have been wanting to do the plate suspension trick for
adjusting downbearing. Del spoke of it at the recent Indy conference. This
involves threading socket cap screws (headless bolts with recessed allen
socket) into the inner rim, running down a lock nut upside down with a
washer on top (a sufficient clearance well counterbored into the
soundboard), the plate lowered onto the washer, a chrome washer and acorn
nut on top. The height of the plate can then be easily raised or lowered by
removing the acorn nut and turning the stud with and allen wrench.

    Attached is what I ordered. I got the hanger screws just for fun. If the
machine thread doesn't work well, which Del said it would thread right into
the wood, I can always fall back on the hanger screws with their lag thread.

    Does anyone have a recommended hole size to drill the rim for the 3/8"
machine thread to screw into?

    Blessings,

    Dean

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