Question:
I have a small cast potmetal part from an electric guitar bridge that I would like to have reproduced. I have one broken part and five remaining intact ones. These are no longer being manufactured and replacements are unavailable (I've been all over the web looking). Apparently the potmetal used to make these was not strong enough to handle the prolonged stress of tension of a tuned guitar string and breakage was a very common problem with these parts. Thus, if possible, I'd like to have them reproduced using something stronger than the original potmetal (I've been told this is a zinc alloy of some sort). The part itself is basically composed of two cylindrical portions intersecting in a T shape. The top of the T has a threaded hole from one end to the other. The intersecting cylinder also has a lengthwise threaded hole which intersects the other threaded hole. The rough dimensions of the entire part are about 8mm x 6mm x 6mm (i.e., not very big). Now, like my header says, I'm not quite sure where to go with this. Is this the sort of thing I could go to any machine shop with and ask them to reproduce? Is it possible to make a mold from an existing intact part and reproduce from that or does the threading and small size complicate that? Finally, I know without much more detailed and specific information, it is difficult to estimate costs on this sort of thing, but if it is no more complicated than creating a mold from the existing part and cranking out 10-100 of them, is there any chance in the world it would cost me less than a couple hundred bucks?
Answer:
Casting alone won't do it - the threads will have to be machined. A foundry should be able to cast them for you in aluminum or brass or bronze. If you can stand a bit of shrinkage, they can probably use an existing part as a pattern. Cheaper than casting, for a small quantity, would be to have some welded up from bar stock. Or, even better, find a T shaped screw or handle from which they could be cut. Check with a jewelry benchman, who may be able to pull a mold from one of the good parts, then investment cast them in silicon bronze. They will require some machine work afterwards, but investment casting will yield the profile in perfect detail. He may even be able to compensate for shrinkage by plating the original part with copper, a common practice when pulling a mold from another item.
Add to favorites
