RE: [CAD_CAM_EDM_DRO] Re: small spindle ?

> the real question is the person selling the parts and their point of view.

if they

> make 100 parts and the absolute worst has a run-out of 0.0015 and 99 have
> run-out of 0.0002, do they claim 0.0015"
>
> if they make 99 that are 0.0015 and one that is 0.0002, do they claim

0.0002 ?

>
> modern sales would say they have shop-grade and sell at one price and then

QC

> grade and sell for more.

I'd sell 'em as 0.0002 +/- 0.0005, but maybe that's just me.

Joking aside, you make to the highest quality and then sell the 'failures'
at a lower grade.

This leads to oddities at times, sometimes you find lower grade items that
actually meet the spec for the next grade up. It may cost the same to make
the part regardless of grade (often the only real difference is in testing),
so if they have a 'good day' they'll downgrade some parts to meet the supply
for the lower grade. Marketing does strange things to people.

That happens with computer CPUs occasionally. They all come off the same
production line, and are graded according to speed. Sometimes you can
'overclock' a low grade part to a higher speed. Sometimes it's even
reliable.

You get a different phenomenon with parts like resistors. They're made to a
certain value, and specified with a tolerance, usually 5% or 1%. So if you
buy a roll of 100 ohm 5% resistors, you should find values across the 95-105
ohm range. You will, however, fail to find any in the 99-101 ohm range.
The reason? Well, guess where the 1% range comes from...

Ferrari, on the other hand, toss the duds back into the smelter.

Tony