I managed to make the keyrings that I posted about earlier. Nickel is possibly the worst material I have ever machined. I will never, ever, make anything out of Nickel (pure Nickel 200) again. Maybe I'll do some Nickel Silver as it should be easier to machine, but we'll see. I'm somewhat traumatized by the experience. Nickel is hard and gummy, how the heck can something be hard and gummy? I wore out an endmill on each one I made. The copper wasn't that much fun either, but at least it's soft and gummy... I thought I could just use the double stick tape I use on the earrings, but the nickel got so hot that it just melted the adhesive and let go...even when using coolant it was turning it to steam at points. I did learn the virtue of climb milling when machining Nickel, as a change in the program made it a bit easier, conventional milling just made it work harden that much faster. I didn't mention that it work hardens? Yes of course this demon material would do that, wouldn't it?
My final setup for milling the keyrings.
Copper milled ok. I should have probably used milk as a coolant, that's what the old-timers suggest.
Two copper keyrings held by the sheet.
I programmed the toolpath to leave 4, .01" thick tabs spaced evenly around. I snipped those to free the keyrings.
Sanding the keyring to give a brushed finish. That granite surface plate was a bargain at an auction and had a few dings so I don't feel bad using it as a flat lap.
The Nickel keyrings. Compounding my hatred of nickel was the fact that the plate I bought had pits, and the sheared edges of the piece I bought distorted the material.
The copper keyring.
I didn't really make any money on this except that I have a large piece of copper left over.
I think any element keyrings I make will be available in any metal the customer wants, as long as they want lovely free machining brass. Brass? Have I mentioned how much I missed you? I'm sorry I left you for a more exotic metal, baby, but I'm back and I love you all the more for the experience. Just give me another chance, you golden hued, wonderfully machinable alloy, you...
Here are two different .pdf files about machining nickel: one, two.