Re: Router - ballscrew on one end

Les, All,
Thanks for the input. I will do some solid modeling and FEA but
because of my uncertainty on how to model the linear ways I am more
comfortable with real experience.

The rails are 2.5" tubes, about .375 wall and have heavy adjustable
support brackets on about 12" centers. Linear bearings are open design
mounted in aluminum blocks. The x and y ballscrews are about 1.25". I
got these surplus and have no idea of what they were used for. The two
z axis rails are the Thompson flat style about 2" wide with dual 3"
long trucks. I still need a z ballscrew. This assembly will be too
heavy for fast rapids but I'm hoping that wont matter too much with a
48" square work area.

With rails mounted over the table the x/y will be on the same plane. I
can't mount the screw over/under the X as it would interfere with the
30" z.

Roger

> This is fairly common in industrial machines. You do need to make the
> gantry a bit bigger to stop it flexing but otherwise it isn't a problem.
> Another trick with a single screw is to put it in the middle under the
> table with bars going to each side. The table then has to become a
> bridge over the screw, supported only on each end. As it isn't a moving
> part there is no penalty in making it beefy enough to be rigid. I did
> this on the router I built and had no problems with flex or binding.
>
> Are these rails supported or unsupported? If they are unsupported, even
> big rails flex like crazy.