Re: [CAD_CAM_EDM_DRO] Ball screws

ryan_kittredge wrote:

>
>Hello group;
>During some internet research I came across Kerk motion that has
>lead screws with anti backlash nuts that they claim to be less
>expensive and out perform real ball screws.
>
>I am interested if anyone knows anything about these and where good
>ball screw / lead screw suppliers are.
>
>

I have used the Kerk screw/nut assembly for the optical carriage on my
photoplotter. They are not meant for delivering a lot of linear force,
such as
a lathe or mill would need. They work VERY well in very light load
situations,
though.

>I also noticed that a lot of ball screws do not have the
>standard .100" per rev lead that is the standard for the machines.
>

Most larger machines have a .200" lead. The Bridgeport knee has .200
screws, too, but uses a bevel reduction gear in the knee to make it
easier on your
arm. That's why that has a .100" advance at the crank and dial.

I have a .100" lead ballscrew on the quill of my Bridgeport retrofit. I
think
it is the only .100" ballscrew I've ever seen. The balls obviously must be
SMALLER than .100" diameter, so the load capacity of these screws must
be less.

>Does the controller software like mach2 compensate for this?
>

Yes, any software worth trying had better have the capability to accept
different
resolutions per step. For one thing, you can put in numbers slightly
different from
nominal to compensate for variations from the perfect screw pitch.

Jon