Re: [CAD_CAM_EDM_DRO] Metal selection 101

----- Original Message -----
From: <indigo_red@...>

> My goal is to find a steel that is easy to machine and can be sent
> out to be hardened if needed. This will be for general purpose
> toolholder/vises etc
> Any suggestions?

Opinions differ, but I like A2 air hardening tool steel because it is easy
(for a tool steel) to machine and less likely to crack during heat
treatment. Forgives bad design (stress concentrations).
>
> What field tests can be done to determine if a piece of scrap steel
> may be useful for machining? Tim mentioned the spark/grinding test,
> and I was also thinking of a spring loaded punch and battery powered
> drill. Are there tips from the
> experience pool on this...

I've been fortunate enough to find it with the label still stuck to it -
generally a strip of tape along it's length. The school I taught at had
been given several tons of tool steel over the years. Manufacturers donated
it because their machinists were too lazy to properly mark each bar and thus
lost it's identity. End color codes are only good if you know the
manufacturer of the steel.

I got three pickup loads from one company whose new manager walked into the
shop one day and said "get rid of this mess." That was the only properly
marked tool steel I've ever seen given away. I have been grazing on it for
two years.

As for spark testing and such, there are too many alloy variations today to
trust those methods. Experimental heat treating of samples will get you
farther if you have the time and your own oven.

Doug