[CAUT] In need of Mason & Hamlin shift lever

[Delwin D Fandrich]

| -----Original Message-----
| From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On 
| Behalf Of Jim Busby
| Sent: December 02, 2006 9:12 AM
| To: College and University Technicians
| Subject: Re: [CAUT] In need of Mason & Hamlin shift lever
| 
| Jeannie,
| 
| We have a guy who is very successful at welding cast iron 
| (which, according to Del is "grey iron") using nickel rod. He 
| has welded over 100 plates without a single failure! So FWIW, 
| I think the nickel rod is best. This man also says the secret 
| is to weld only about 1/2 inch at a time then wait until it 
| has cooled so it is only warm to the touch. 
| 
| Good luck!
| 
| Jim Busby

To say an object is made of "cast iron" is something like saying hamburgers are
made of "ground meat." There is the low-fat, organically grown ground top
sirloin you get at your local meat shop and then there is the medium-grey sludge
you find in a Big Mac. 

Iron castings can be made of a variety of irons and they can yield a variety of
mechanical characteristics depending on the casting technique used. The iron
typically used in piano plates is called "grey iron" because its fracture line
is grey in color. This color is due to its relatively high carbon (in the form
of graphite) content. 

Even using the term grey iron is somewhat ambiguous. The tensile strength of
what we call grey iron can, and has, varied considerably from one foundry to the
next and from one age to the next. O.S. Kelly is now pouring what is called 30K
(or Grade 30) iron. This means that a test sample of some given length and with
a 1 in2 cross-section will break at approximately 30,000 pounds of tension. 

This has not always been the case. There is some evidence that over the history
of the piano the tensile strength of the iron used to pour piano plates has
varied from a low of around 12K to something higher than 30K. There is no way to
tell for sure without actually breaking the stuff. 

Now, this may or may not have anything to do with the iron found in Jeanie's M&H
action shift lever. If the lever was cast at the same foundry as the plate it is
likely that it was cast of the same iron mix as was common to the plate casting.
If, however, it was cast by a local foundry it could be most anything. My guess
is that it is, indeed, a grey iron mix. If it were malleable iron or ductile
iron it is unlikely that it would have broken.

Whatever the actual iron used to cast the action shift lever, I agree with most
of the writers who have suggested that she simply have the original welded or
brazed as appropriate to the individual piece. A good welder should be able to
pick the appropriate repair. As with the others who have recommended welding,
I've had this done numerous times to pedals, shift levers and plates without any
failure to date.

Del