Cracked Plate!

[Robert Goodale]

A 1/4" crack?  That's not a crack, that's a chasm worthy of mule trails 
and a camp ground!  Even with a 1/4" crack the Lock-N-Stitch system 
should be able to repair it although you would probably have to use a 
large pin size and probably the stitching plates.  Is this piano worthy 
of the repair?

The Lock-N-Stitch system works in two ways.  The first part are the 
specially engineered screws called "pins".  A hole is pre drilled to an 
exact diameter into the crack.  Then a special countersink tool is used. 
 Then threads are tapped into the hole.  The tools for all of the above 
are included in the kit.  Next a sealing compound is dabbed into the 
hole and the special Lock-N-Stitch pin/screw is inserted.

The pin/screw is not what you would normally think of as a screw.  The 
threads are tilted upward in a very strange way.  They grip the sides of 
the cast iron and will actually pull a crack together.  When the screw 
bottoms out in the countersink the head breaks off at a pre determined 
torque for a precise fit.  The screws themselves are made of a special 
alloy that is similar in hardness and characteristics of cast iron so as 
it tightens the threads actually meld together in a permanent fit.  The 
really strange part of all this is that once the screws are broken off 
and ground down flat you can then drill out and install another pin 
right through a portion of the last one so that they overlap each other! 
 The previous pin will have become one with the cast iron as if a crack 
was never there!  Using a series of overlapping pins you fill the entire 
crack.  If a crack is bad enough and wide enough you can install 
stitching plates as well.  These are locking devices that go in the 
opposite direction of the crack and can technically bolster the strength 
beyond what it was originally.  Once the repair has been made you can 
smooth it out with a little filler and paint it and it will be as if 
there never was a break.

The idea is quite revolutionary and has an incredible track record.  You 
can request a video tape from the company that shows the whole process 
including stress tests.  When ordering tell them that you are a piano 
technician and you need the kit appropriate for piano plates.  They will 
know exactly what you need.

Rob Goodale, RPT
Las Vegas, NV


Greg Casper wrote:

>I have looked at the website for Lock-n-stitch. Will this work across an
>actual BREAK in the plate, because that's what I've got. It's not just a
>crack, but actual total separation of the two pieces. Probably 1/4 inch
>between the two pieces. Can't tell from the website, but is Lock-N-Stitch
>still a viable option in this case?
>
>Question 2... if this plate is completely useless, can a replacement plate
>be used and where might I find such an item?
>
>Thanks
>
>Greg Casper
>San Jose, CA
>
>-----Original Message-----
>From: owner-pianotech@ptg.org [mailto:owner-pianotech@ptg.org]On Behalf
>Of Robert Goodale
>Sent: Saturday, March 23, 2002 10:02 AM
>To: pianotech@ptg.org
>Subject: Re: Cracked Plate!
>
>
>I would suggest the "lock-N-Stitch" cast iron repair kit.  It is cheep
>and effective and in most cases can be done without removing the plate
>from the piano.  This topic has been brought up several times so I might
>suggest you check out the archives.  I have done it and can tell you it
>DOES work.  This system was also featured in a class at  the Reno
>convention by the inventor.  Their web page is here:
>
>http://www.locknstitch.com/
>