make your own rail supports? was Re: Extrusion sizes

Jeff,

Have you priced/sourced the filled polyurethane yet? Petty pricey
stuff...

I don't care for this technique. I believe it will cost nearly as
much as the "commercial" alternative (DEFINITELY will if your "time"
is figured as a cost). And it will reduce the ability to adjust the
straightness of the rod with shims, both initially, and over time.
(with the "commercial" low rail, shims can be inserted underneath the
rail support; the taller "tee" rail support that this technique
emulates provides enough rigidity that shims are better placed
between the top of it and the round rail. This is not possible with
the bonded beam of polyurethane.

Bottom line, IMO, is that the top line of this link is at odds with
the technique shown. The claim is made that everything should be made
ajustable; followed by a technique that is not very adjustable. (You
had better get it right while that poly beam is setting up, IMO.)

Hope this helps.

Ballendo

--- In CAD_CAM_EDM_DRO@y..., "jeffgnu" <zbadone@b...> wrote:
> I have been thinking of my XYZ table design for some time now, about
> ready to purchase the material. I already have my steppers, a Linux
> box running EMC.
>
> I've also looked at the open style Thompson bearings, very expensive
> for my hobby. I've looked into roller bearings, from in-line skates.
> Difficult decisions to make.
>
> I have seen someone use a method of making thier own support rails
for
> the open style bearings. With the support rails you could reduce the
> size of the bearings to a smaller size, at least for my application.
>
> Check this out:
>
> http://www.super-tech.com/root/mechInfo/rodmounting.htm
>
> I'm now leaning in this direction.
>
> --- In CAD_CAM_EDM_DRO@y..., Chris L <datac@l...> wrote:
>
> <snip>
>
> >
> > Open bearings ?? Well, I see that could work very well too. I
prefer
> to use
> > those low profile steel stands from thomson but even they are
> pricey. So,
> > next, one needs to find a really cheap but adequate "Stand" for
the
> > predrilled rails. Thats why I'd start with closed