Re: [CAD_CAM_EDM_DRO] Re: Looking for short ballscrew

Jon Anderson wrote:

> Pete,
>
> Well, I started out with this line of thought first off because I was
> under the impression the head I want to adapt to my mill would not
> directly adapt, and I thought maybe I could build the Z slide cheaper
> than buying the commercial quill drive.
> Given what I had, it would be totally marginal at best. Larger rails
> certainly are called for, and once I start factoring in the cost of
> those, I lose any advantage to DIY, even if I don't factor labor into
> the equation.

Yes, I think you are right. The Bridgeport J head weighs over
200 Lbs (including motor). The quill, spindle and bearings alone weigh
over 100 LBs! (Maybe it is just under 100 Lbs. but tricks you because
it is so hard to hold.) Anyway, the quill, some 18" long, fitted into the
housing with .0002" clearance, is a mighty stiff structure. You would need
some VERY large linear rail assemblies to match that kind of stiffness.
The farther out it is cantilevered, the worse the situation gets, too.

Jon