[CAD_CAM_EDM_DRO] Re: Long Acme threaded rod

If you have the belt teeth down, then what you could do is get another
belt, and glue it to the table, teeth up. The belts now mesh together
giving you a quasi rack-n-pinion. The upper belt is now highly restricted
from moving.

Or, once the machine is going, you can mill your own 'tooth up' blocks of
aluminium and bolt them down, underneath the actual belt. Maybe 80mm long
apiece, spaced every 250mm.

Regards
Roland

On 17 June 2013 21:10, AlienRelics <alienrelics@...> wrote:

> **
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Tony Smith" <ajsmith1968@...>
> wrote:
> >
> > > I'm working on designing and building a CNC mill/engraver. I'd like it
> to
> > have
> > > a cut volume of approximately 1000x1500x100mm (about 3ft by 5ft by 4
> > > inches) that can cut aluminum plate and hardwood, at most. I expect to
> > take
> > > multiple passes to cut through an aluminum plate.
> >
> >
> > Belt drive works fine. Have a look at
> > http://www.automatedwoodworks.com/Videos.htm, about 1:10 into the first
> > video might interest you. It's a shame he doesn't mention how long those
> > pieces took.
> >
> > www.mechmate.com is worth a look, might be a bit much though.
> >
> > Ignore hanero and his usual BS about machines being rubbish unless being
> > built of unobtanium & capable of sub-micron accuracy. (Google his posts,
> he
> > has some rather, ahh... amusing gaps in his knowledge.)
> >
> > Tony
>
> Thanks! I think I'll revisit the idea of using timing belts. I don't need
> sub-micron accuracy, after all. The ShapeOko has a static belt with rollers
> wrapping it around the motor pulley, but teeth up. I'd mount it teeth down
> and on the outside to avoid having a lot of debris settling on the belt.
>
> I see some people saying that the cut volume I gave is too small to be
> useful. I am going to guess that those were meant to be funny? I figure,
> large enough to engrave a door, although not the entire thing at one time.
> Large enough for what I want to mill. I'd love to have one that I can load
> a 4x8 sheet of anything into, but don't have the money for it. And I wasn't
> planning on making furniture with this.
>
> I will be comparing the cost of linear bearings with steel rails vs 8020
> and V roller bearings. 8020.net has a bit of software that will give
> deflection vs weight for all their sizes of extrusion, and it takes
> unloaded deflection into account.
>
> So I've only cut relatively thin aluminum with a carbide blade in my table
> saw. Has anyone here had any experience using a table saw or chop saw to
> cut 8020 aluminum extrusion?
>
> Steve Greenfield AE7HD
>
>
>


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