Re: [CAD_CAM_EDM_DRO] Re: What makes a machine CNC ready?

John Stevenson wrote:

>
>
>>Well, I built a laser photoplotter that has a laser-writing carriage
>>driven by a stepper motor.
>>it travels at 10 steps/second, with each step = 0.001" at a continuous
>>rate during the image
>>generation. I used one of those cheap black Thompson screws first, and
>>it proved the concept,
>>but thread "drunkenness" ans backlash caused image artifacts. I then
>>replaced the screw
>>with a Kerk selected precision screw with the automatic plastic
>>anti-backlash nut, and it works
>>VERY well. It has zero backlash, and even .001" backlash would show up
>>clearly in the plots.
>>
>>
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>
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>>I think these Kerk screw/nut assemblies work quite well for low-load and
>>moderate speed
>>applications. And, the Kerk set cost almost 10 x more than the cheap
>>ballscrew, but performs
>>much better.
>>
>>Jon
>>
>>
>>
>>
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>Most precision ballscrews are X3 or X4 the price of the cheaper rolled ones so going to X10 and what advantages do you have over ground double nut ball screws?
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This is a rolled-thread screw with a plastic nut. A 2 foot length
selected for the level of
precision I needed (I think it is about .001" per foot, cumulative) ran
under $150 for
the screw and nut. I'd never get CLOSE to that price for a ground
ballscrew with anti-
backlash nut.

Jon