Polishing mixed metal standard blocks

[Gseward]

Dear Forum members,

I am looking for advice for polishing mounts that contain a variety of metals with with vastly different hardness. I consider myself 'capable' with respect to polishing, however this block has me cursing. It is a stainless steel 1" round with about 35 metals plus BN and a few other simple compounds. There are soft metals like Pb, Bi, Te and then at the other end of the hardness spectrum, W and BN (assuming it is cubic). After my initial attempts I am left with many of the soft materials below the surface of the block (which I guess means I had it too long on to a substrate with too much nap).

I intended to try lapping films as a starting point for my next attempt, but I suspect I'll have to go back to something pretty coarse to get the surface flat again. I also considered using a micromill with some sort of polishing head, to polish each material in isolation, but this seems a little extreme. Any suggestions would be most welcome.

Many thanks,

Gareth

[Probeman]

I am looking for advice for polishing mounts that contain a variety of metals with with vastly different hardness. I consider myself 'capable' with respect to polishing, however this block has me cursing. It is a stainless steel 1" round with about 35 metals plus BN and a few other simple compounds. There are soft metals like Pb, Bi, Te and then at the other end of the hardness spectrum, W and BN (assuming it is cubic). After my initial attempts I am left with many of the soft materials below the surface of the block (which I guess means I had it too long on to a substrate with too much nap).

I intended to try lapping films as a starting point for my next attempt, but I suspect I'll have to go back to something pretty coarse to get the surface flat again. I also considered using a micromill with some sort of polishing head, to polish each material in isolation, but this seems a little extreme. Any suggestions would be most welcome.

I am still hoping that Tim Teague at UC Berkeley will respond to your questions... he is the world's expert on these topics.

All I know from hearing him talk about this is that to minimize "relief" between hard and soft materials, one needs to use a hard lap with a fixed abrasive...  only use the soft lap at the very end for final polishing of the softer materials.