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PostPosted: Sat May 05, 2012 2:16 pm 
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Location: N.S. Canada
Richard_W wrote:

I was wondering if you were concerning yourself with the ball screw only and not taking into account the weight of the table and friction of the sliding surfaces when you wrote the above?
Richard W.

No Richard, I was not disregarding the weight and friction. but, I know that climb milling even with a regular feed screw can be a little more problematic than cutting against the feed direction.
I'm glad you have had success without encountering my concerns.
Steve


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PostPosted: Sat May 05, 2012 2:20 pm 
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Cadmandu wrote:
Hi Richard and Steve,
We all have divne intervention just some are aware of it and some are not.

If that is your opinion you are welcome to it but please don't profess it to others who may not share it.


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PostPosted: Sat May 05, 2012 3:36 pm 
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stevec wrote:
Cadmandu wrote:
Hi Richard and Steve,
We all have divne intervention just some are aware of it and some are not.

If that is your opinion you are welcome to it but please don't profess it to others who may not share it.

True. Religion is a forbidden topic on this board. Regardless of one's choice, it should be parked at the curb when paying a visit here. That way no one is offended. Politics, too!

Harold

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Wise people talk because they have something to say. Fools talk because they have to say something.


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PostPosted: Sat May 05, 2012 4:22 pm 
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Location: Molalla, Oregon
Cadmandu wrote:


I feel the same as this quote on your link.

" Opposition to ball screws seems to be more theoretical than experience based. "

Kinda reminds me of others issues over the years that I have worked in the trade.

Richard W.


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PostPosted: Sat May 05, 2012 7:14 pm 
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I found this on the link "Great for backlash, but there isn't adequate friction to keep the screw in place.
You would need to introduce friction, not so much to lock the handwheel, but to keep force on the table from moving the table.
Some sort of plastic block rubbing/gripping the shaft would be a good start; get a spring in the system to keep the friction consistent.
If you can't figure out a way to introduce friction, don't install the ballscrew. "

I went further and found supporting posts. I didn't find the "Opposition to ball screws seems to be more theoretical than experience based" post but I'll let this go due to no personnal experience at all.


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PostPosted: Sat May 05, 2012 8:41 pm 
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Location: Florida
I had a friend that retrofit manual machines to ballscrew and NC control back when NC was as good as it got. He had a standard old manual Bridgeport that he had converted to ballscrews and told me if I ever used one with ballscrews I'd never want to use an Acme screw Bridgeport again.

Dunno all of the details as I never asked, but I remember him showing me the machine and telling me that.

Doesn't mean that it didn't have any drifting issues though.

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Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!


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PostPosted: Sat May 05, 2012 8:45 pm 
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Joined: Thu May 03, 2012 6:25 am
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You guys are right, I apalogize for not being politically correct. I just have such a habit of thinking and speaking that way it is really hard to think like the world does. I will filter all my thoughts from now on before posting.

Does anybody know if the X axis acme screw is longer or different if a 150 Servo is attached?


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PostPosted: Sat May 05, 2012 9:18 pm 
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Location: Molalla, Oregon
stevec wrote:
I found this on the link "Great for backlash, but there isn't adequate friction to keep the screw in place.
You would need to introduce friction, not so much to lock the handwheel, but to keep force on the table from moving the table.
Some sort of plastic block rubbing/gripping the shaft would be a good start; get a spring in the system to keep the friction consistent.
If you can't figure out a way to introduce friction, don't install the ballscrew. "

I went further and found supporting posts. I didn't find the "Opposition to ball screws seems to be more theoretical than experience based" post but I'll let this go due to no personnal experience at all.


They had several people from both sides sounding off. This quote was in post #11 and the guy teaches in a school and has students running the machines with no problem. The quote isn't high lighted in the post, but is written in the first part of the post.

It reminds me of an old timer who told me gear head lathes were dangerous and you got gear marks in your finish. Yet there was nothing wrong with changing speeds on a line shaft drive lathe with the spindle running and moving the belts by hand from one speed to the next.

Richard W.


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PostPosted: Sun May 06, 2012 9:52 am 
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Richard_W wrote:
It reminds me of an old timer who told me gear head lathes were dangerous and you got gear marks in your finish. Yet there was nothing wrong with changing speeds on a line shaft drive lathe with the spindle running and moving the belts by hand from one speed to the next.
Richard W.

I wonder if he noticed marks in his finish from the belt lacing everytime they went over the sheaves? :roll:


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