On Tue, 9 Nov 2010 10:28:30 -0700, "Bob La Londe" wrote:

"Larry Jaques" wrote in message
.. .
On Mon, 08 Nov 2010 20:38:48 -0600, Karl Townsend
wrote:

On Mon, 08 Nov 2010 19:07:00 -0600, Karl Townsend
wrote:

"The Kid" just got a new laser to play with where he works. You get a
lot of toy for $300K. It claims .003 accuracy, he says you can do .001
with careful setup and watching your cut conditions.

Karl

shoot I didn't copy a link to one running:

http://www.youtube.com/watch?v=iJfQR...eature=related

Amazing! But, WOW, I'd hate to see those lead screws after a month of
that. I wonder what the maintenance schedule is on an industrial CNC
laser.

Its my understanding that for machines like that they use precision balls
screws with preloaded nuts because the service life is very predictable.
Does seem like over kill to make perforated metal sheets though. LOL. I
like it.

Very very few CNC machines these days use anything other than
ballscrews. Frankly..they are far far more precise, keep their accuracy
longer and are easy to swap out when they ultimately do start loosing
accuracy.

And they can be pretty cheap when you add up the advantages over lead
screws.

Im not aware of ANY cnc machinery that uses lead screws any longer.
There is a reason that machines are faster and more accurate these
days..and ballscrews are one of the prime ingrediants.

I replaced a 12 yr old ballscrew in a CNC lathe this week. Its been run
8-16 hours a day 6 days a week for those 12 yrs, in some of the nastiest
water based coolant conditions one could possible imagine. And in 12
yrs..it finally started showing up (7) tenths....(1) 10,000ths of an
inch backlash..resulting in up to .0004 parts miss-tolerance. And since
the owner needs 0/+.0002 accuracy..he had me replace the ballscrew. Cost
him under $800 total.

Try that with a leadscrew......

Gunner, machine tool repair tech


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"Confiscating wealth from those who have earned it, inherited it,
or got lucky is never going to help 'the poor.' Poverty isn't
caused by some people having more money than others, just as obesity
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Poverty, like obesity, is caused by the life choices that dictate
results." - John Tucci,