RE: [CAD_CAM_EDM_DRO] Re: small spindle ?

> DARN DECIMALS.....
>
> if you make one at 0.0001 and 99 at 0.002
>
> you have one great one, 99 average.
>
> do you advertise 0.0001" or 0.002"
>
> best practice would be to separate that great one, sell it for more $$ and

be

> honest in the advertising.
>
> The next real question is that of needed run-out. how many machines and

parts

> do we all have that are
> #1) capable of cutting to 0.001"
> #2) have parts that require such accuracy.

I noticed the decimal, "eh typo", we know what you meant.

How you sell the part depends on the market, as you say do many people need
that one really good part? Finding that part is expensive, it takes better
measuring tools (which need to calibrated and all that), more time, training
and so one. Something needs to wear the extra cost so that one part winds
up paying for measuring the 99 duds. And then no-one buys it because it's
too expensive.

Most of us would have equipment that can cut to 0.001", whether we have the
experience is another matter. And not just cutting it, even measuring it
takes a bit of skill.

Few parts need that sort of accuracy, that's for sliding parts (piston &
cylinders etc). I've seen a lot of shops specify 0.01" as a 'worst case'
number (that's the thickness of a few sheets of paper) and aim for half that
in practice.

Design & planning mostly beats accuracy anyway. Got two plates that need
holes evenly matched? Machine them together, taper bearing to align shafts
etc.

Isn't that the old joke about Germans? Given a bad design they'll just
keep making it more accurate until it works.

This reminds me of a bloke on another list who was going to make a set of
spanners as show pony tools to show off what his CNC could do. Fair enough,
but his reasoning was standard tools were crap because they were inaccurate.
Eh?

He'd missed three points; one was that your 13mm spanner will actually be
13mm (even my junk ones were spot on), nuts are made undersized anyway (way
more than 0.01", never mind 0.001"), and lastly I'd like to see someone put
a 13mm spanner on a nut that was exactly 13mm. (Ok that one... now do the
rest...)

Tony