Re: Direct coupled ballscrews

You'd have 2000 steps per .200 travel, which would give a smallest
increment of .0001" Others here are better suited to tell you about
the motor size you need. If the bed of a machine is of the quality
such that it has turcite lined box ways, anybody that would whack them
off to install linear ways must either be building a special purpose
machine......or they're totally out of their minds :-)

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "knives01us" <knives01@a...>
wrote:

> I bought one of the CNC ready mill frames that AmeritechCNC is
> selling as surplus. Somebody posted that these were available last
> fall, there were still a few left last week. It's very solid (900
> lbs) considering the table only travels 10" x 8", and should be
> perfect for the small parts I do and my shop space.
>
> The machine is built with brackets for direct coupled axis motors.
> Because of this, it would be difficult to use toothed pulleys and
> belt reduction to drive the ballscrews.
>
> My question: would I get good resolution (.0001") direct coupling
> stepper motors to the 5 turn per inch ballscrews using a 10 step
> microstepping drive? I would prefer to use steppers, I was thinking
> 1,200 oz/in might do it. When the factory builds their machines they
> use direct coupled 15 in/lb servos, but they machine off the Turcite
> lined dovetails and mount linear bearings so there's less frction.
> The table & saddle are probably as heavy as a large mill-drill,
> although the table is only 8" x 19 1/2" it is very stout.
>
> Any thoughts or experiences with similiar setups?