Re: Long Acme threaded rod

--- 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