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Re: How do I make My own HB covers?

7/1/2005 4:21 PM
Joe Gwinn
Re: How do I make My own HB covers?
On 6/29/2005 1:45 AM, A nonymouse said:  
"Nickel silver is not so easy to draw. Harder than brass."
Harder, yes, but quite possible. I think one must anneal the workpiece between each draw. The trick is to heat the metal to a dark red heat (or just under) and then quench it in water. Non-ferrous metals work the opposite to ferrous metals, so this hot quench leaves brasses (including nickel silver) soft, whereas it would leave steel hard.  
When the drawing and annealing steps are done, pickeling in acid will restore the appearance of the metal.  

"What you want is a non-ferrous metal with the highest possible electrical resistivity. Non-ferrous so it does not change the magnetic fields. High resistivity to reduce eddy currents."
Non-magnetic is the real issue, not non-ferrous, as not all ferrous alloys are magnetic. So, we are looking for a non-magnetic alloy with high resistivity that's cheap and easily drawn. I wouldn't worry about soldering too much, as there are fluxes that allow just about anything to be soldered.  

"Nickel silver does have one of the highest resistivities. A few stainless alloys are higher. Not as useful because they're ferrous. The pickup would have to be designed to accomodate that. "
Most stainless alloys are totally non-magnetic. The exception is the high-carbon stainless alloys like 440C, which are used for knife blades and the like.  

"Titanium is also higher. Too complicated."
I'll say. Drawing titanium is not easy. Nor is soldering it. Or drilling it. It is strong and pretty though - people make jewelry out of titanium.  

"Tin is a good choice. As much as twice the resistivity of nickel silver and much higher than brass. Easy to plate. Easy to solder. Easy to draw. Inexpensive."
Tin is very pretty, but is dead soft. For a pickup cover, this may or may not matter.  

If one is making only a few pickup covers, there are some traditional ways to making hollow ware that ought to work. The simplest would be to make a hardwood mold and matching stick with rounded tip that one uses to hammer a metal sheet into the mold cavity. Multiple anneal steps are likely to be needed as the required amount of stretching of the metal is great. The process is similar to chasing, also known as repousse. Books on jewelry making and silversmithing will describe the process.


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