[CAUT] Aluminum hammer rail (Screw hole) repair

[Mark Cramer]

Don,

thanks, this is a brilliant repair!

I watched the original hole-size shrink before my eyes.

A clearance test with jobber-sized transfer punches proved that the swedging
actually reduced the nominal size of the hole by 3/128ths of an inch, plenty
enough depth for new threads.

The original flange screw re-tapped the hole nicely and I have a serviceble
part once again!

Not counting the time it took for me to run down to the shop and back again,
the repair took less than three minutes!

Again thanks Don, you are an amazing technician and highly valued colleague!

sincerely
Mark Cramer,
Brandon University

PS Okay, so I made a few more lines than you recommended, and my repair
looks more like Phyllis Diller's eyelashes than the iconic morning sunrise,
but it worked!  :>)


  -----Original Message-----
  From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org]On Behalf Of Don
Mannino
  Sent: Wednesday, June 27, 2007 12:51 PM
  To: College and University Technicians
  Subject: Re: [CAUT] Aluminum hammer rail (Screw hole) repair


  Mark,

  A couple of other repairs that work well if the hole isn't too far gone .
. .

  1. Oversized screws are available from Yamaha - or at least, they used to
have them.  I haven't checked recently :-)

  2. Swedging the hole works very well in many cases.  I use a fine
screwdriver with a sharp tip, position it at the edge of the hole and tap
with a small hammer until you have a mark in the aluminum.  Repeat in a star
pattern around the hole on all sides, so that you end up with 8 little lines
radiating out from the hole.  The original screw should tighten normally
now.

  In extreme cases I have turned the rail over and repeated the swedging on
the bottom as well.

  Really, the hole would need to be really, really badly damaged to require
a threaded insert, but I can see that happening.

  Don Mannino



----------------------------------------------------------------------------
    From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of
Mark Cramer
    Sent: Wednesday, June 27, 2007 9:34 AM
    To: College and University Technicians
    Subject: Re: [CAUT] Aluminum hammer rail (Screw hole) repair


    How timely Barbara and Jim, I'm just traveling a new set of S/F's on a
1976 C-7 and found a stripped hole in the bass.

    Can you suggest a place to look for this kit... auto supplies, etc? Does
it have a parts number, or go by the thread size?

    Otherwise, I seem to recall someone suggesting there was a nominal
upsize thread (imperial or metric?) that could be used.

    thanks,
    Mark Cramer
    Brandon University

    PS The alignment groove in the aftermarket parts I'm using doesn't quite
line up with the wire Yamaha recesses into their action rails. This pulls
the flange away from the lip that the flanges butt against, making it
difficult to get a nice alignment.

    Fortunately, there's a recess in that lip, and I was ABEL to thread a
peice of #16 music wire between and the flange. Now I'm left with about a
.25mm gap between the lip and the flange, but at least it's precise.



      -----Original Message-----
      From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org]On Behalf Of
Barbara Richmond
      Sent: Wednesday, June 27, 2007 10:34 AM
      To: College and University Technicians
      Subject: Re: [CAUT] Aluminum hammer rail (Screw hole) repair


      Hi Jim,

      I bought the Recoil kit, but it has no screws in it.  What screws did
you use?

      John Dewey also mentioned this repair in his class, Action Frame
Diagnosis and Repair, so, if it is OK with you, I will also list him on the
submission since I am putting together a special "TT&T goes to the
convention."

      Thanks,

      Barbara
        ----- Original Message -----
        From: Jim Busby
        To: College and University Technicians
        Sent: Thursday, January 25, 2007 3:58 PM
        Subject: [CAUT] Aluminum hammer rail (Screw hole) repair


        List,



        Here’s a way to repair stripped screw holes (Especially if an
oversized screw strips) in an aluminum rail that takes less than a minute or
two. “Helicoils” is what they are called. (See attached pic.)



        You drill out the hole and tap it, then insert the little coil which
disappears into the tapped threads, and then you’re good to go! Maybe this
has been shown on CAUT before, I don’t remember seeing it. The new screw is
actually a machine screw with fine threads so it takes a few more rotations,
but this is way better than anything else I’ve ever tried. The package shows
a bolt, but what actually goes in has a Phillips head and looks like a
normal screw.



        Jim Busby RPT

        BYU
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