RE: [CAD_CAM_EDM_DRO] Re: small spindle ?

How run-out is rated depends on the manufacturer. Some (like PreciseBits)
actually do 100% testing so you know what you are getting; they also use a
fancy laser micrometer that gives you simultaneous three axis measurements.



While run-out does affect the precision of the cut it also has a HUGE impact
on bit life and some on spindle bearings. For some types of work, like
engraving or PCB milling high run-out can ruin your work. Take a look at:



http://precisebits.com/faqs/breaking_bits.htm

http://precisebits.com/tutorials/coletcareprocedure.htm

http://precisebits.com/tutorials/spindle_runout.htm



I have a customer not too far from here that cuts primarily balsa wood and
aircraft plywood. After suggesting several times that he consider upgrading
the router motor he was using he finally switched over to a Bosh Colt and
the PreciseBits collets. He was immediately very impressed with the
difference, better quality of cuts and the Colt was quieter than his old
router too. The real pay-off came over time though. He now buys ½ the number
of bits from me as they are lasting twice as long.



There is a lot of hype in the hobby CNC world, things like ball screws take
on the mythical quality that ‘billet’ accessories do in the automotive
enthusiast world. The problems associated with run-out are indeed fact
though, it just comes down to physics of the matter.



Jeff Birt

Soigeneris.com



From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of turbulatordude
Sent: Sunday, June 17, 2012 9:26 AM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [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.

Dave

--- In CAD_CAM_EDM_DRO@yahoogroups.com
<mailto:CAD_CAM_EDM_DRO%40yahoogroups.com> , "Tony Smith" <ajsmith1968@...>
wrote:

>
> > 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
>

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