Re: Lead screw/Guide rail install/pre-load

--- In CAD_CAM_EDM_DRO@egroups.com, ptengin@a... wrote:

> In a message dated 10/25/2000 11:11:20 AM Hawaiian Standard Time,
> r_fl_z@h... writes:
>
> <<
> My thinking is that this arrangement for the lead screw and

support

> rails will provide adequate support while preventing thermal

effects

> from deforming the linear elements.
>
> Does this sound reasonable? Any alternate plan suggestions would

be

> sincerely appreciated.
>
> Best regards,
>
> Ron >>
>
>
> Ron,
>
> I don't recall what kind of machine this was. If these parts are

close to

> a plazma head and are subject to hundreds of degrees (not a good

thing) ,

> then thermal expansion will be a serious problem. If this is a

system for a

> machine that has virtually no thermal effects such as a pick and

place

> machine, then almost no precautions need be taken. If your linear

elements

> are of the same material as your machines structure, then linear

expansion

> will be very similar.

I'm doing what is essentially a 3 axis router: 48" x 36" x 18" of
cutter travel. It'll have the z-y plane fixed in x, with a
travelling x table moving below the y-z plane. So it's a little
goofy in that the part moves only in x, while the router moves in y-z.

The machine is being built to route out holes in 10 PVC pipe, and to
perform misc. routing of flat sheet and PVC fittings. I want to
build it to route the PVC components, but to also have the ability to
function as a light weight mill for bulding other machines.

Because I want to maintain some decent accuracy, I'll be using a
linear strip encoder to close the feedback loop for the long axis.
This should allow me to simply drive the table to the correct
position and not be concerned with the accuracy of the lead screws.

I don't actually expect to have thermal problems per-say, I'm just
looking for design concepts.


Ron