[pianotech] breaking backcheck wires

[Joseph Garrett]

Ryan asked/said: 
"Subject: [pianotech] Breaking backcheck wires
Message-ID:
<CAE5_a_-k9AFsSEO-E+HOQZdWRtJy96SYTZBc-Xgnqv3donPeoA at mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
 
I have an old Chickering that is coming into the shop that is in fairly
decent condition, but it's biggest problem is all the backcheck wires are
breaking! In the past I have replaced a few by chucking the "jack seat
reaming tool" in a drill and basically cutting a little hole around the
broken piece of wire. Using this method I have been able gain a purchase on
the stub of wire and turn it out (the last time I encountered this, the
original wires were threaded). That was fine for a few broken wires, but
what about an entire set? The problem with the Jack reaming tool is that it
doesn't drill deep enough before it bottoms out on the stub of the wire.
 
I have read about making a tiny hole saw out of a roll pin using a Dremmel
tool. Then it would be long enough to get to the bottom of the wire stub.
Someone also suggested in the archives drilling out from the bottom and
then punching them out from below. However, if the wires are threaded I
could see this tearing out quite a bit of wood or damaging the wippen in
some other way.
 
I was thinking of just copping out and drilling new holes for the new
wires, but I thought I would see if the wisdom of the list would have
anything to say on this topic."
 
Ryan,
For those that are not broken, remove them. (of course after ascertaining
if they are threaded or fluted.<G>) I've encountered a few Chickerings with
the same problem. That's a "HMMMMM??" sort of thang fer sur. If you are
going to replace all of them, make sure you can get replacement wires of
similar size. My memory banks are telling me the wires are longer than
standard. Since we've lost a few suppliers, this sort of part(s) is a bit
iffier imho. As for removing the stubs, I've made an extractor out of 
piece of steel rod with appropriate hole drilled, (longer than wire stub,
larger then the wire diameter). Then I've used a triangle file and made saw
teeth in the end. The teeth need to point so that they cut in reverse in
the drillng. That way when the cutter gets to a certain depth, it will
seize up, around the stub and back the stub out. (make a hole on the side
of the "extractor" so you can remove the stub plug w/a pin punch. Angled
down, of course) Also, the wippen body needs to be firmly clamped in a wood
jawed vise, when doing this. Also, use an appropriate diameter of rod that
will leave a hole that can be plugged with standard plugs or dowels. I
prefer to use plugs but dowels can be used if you glue size the new entry
hole for the wire(s). (end grain sitution with dowels<G>) There are those
who will say that the hole for the wire needs to be in a specific place, as
in that's the way it was designed. As long as the wire doesn't interfer
with function, who cares where the new hole is drilled?
Well, that's my take on it.
Best Regards,
Joe


Joe Garrett, R.P.T.
Captain of the Tool Police
Squares R I