Grooves on steel slugs?

[dwizum]

Hi everyone,

A question came up on another forum I frequent - why do steel slugs used as pole pieces (ie in a Gibson style guitar humbucker) have little concentric ring grooves on their faces?

I'd always assumed it was an unintended artifact of the manufacturing process, ie how the slugs were cut. But someone else mentioned the circles being deliberate. There doesn't seem to be any consensus so I though I'd ask here.

[Helmholtz]

It's actually a single spiral groove - a tool mark produced by cutting on a turning lathe - at least on the old originals.

[J M Fahey]

That.

And cutting at a highest speed trying to quickly make a 10000 or 100000 lot or something, and not re finishing/polishing the rough cut toolmarks, all signs of cheapness.

What Chinese are often accused of, but since it happens on an American Sacred Cow, nobody complains.

Oh well.

Wouldn´t be surprised at some atributing magical properties to those toolmarks and even hotly debating what "year" sounds best

[mozz]

No magical properties but the steel they are made from matters.

[J M Fahey]

Yes, of course.
But you know, sometimes people get OBSESSED on trivial, "cosmetic" matters

[mozz]

I don't know if this picture is big enough but i bought these A2 magnets on Ebay, listed as defective bevel. Instead of a smooth bevel, they have many small flat spots that you wouldn't notice unless pointed out. Got them cheap, now i have 1000 magnets.