[okimoki]

Hi all,
i'm thinking about building a CNC router for a long time now.. I started working on a design i would like (and could afford)..
It would be 16mm MDF construction, linear would be L profile with rollerskate bearings, NEMA 17, overall dimesions 600mmx1000mm..

Does anybody see anything wrong with this design?? Anything that wouldnt work? I know some linear rails would be better, but i don't really need 0,01mm repeatability..
Any comments would be appreciated..

https://www.dropbox.com/sh/a652ubahx...jBAj0SkDa?dl=0

[louieatienza]

I'd probably double at least the gantry legs and bridge to add stiffness. I think also decreasing the distance between pinion and idlers will help mitigate belt stretch; a 180deg. wrap of the belt on the pinion would be ideal.

Other advise would be to look into using round tube or drill rod for the rails. This way even if the angle of the bearings is not a perfect 90deg, they'll still ride well on a round rail. It may teeter-totter on the angle iron. Also dust or debris on the flat may cause a jam, where it would be pushed away with round rail...

[awerby]

I think NEMA 17 motors are too small for a machine this size. Go with NEMA 23 instead. That Dremel tool won't last long in this application; the plastic housing distorts when it gets hot, and then it dies. Get a real router instead. And the MDF is okay for a table, but find a piece of aluminum to use as a gantry; MDF isn't rigid enough to do much for you there. I've seen that kind of belt drive used on 3D printers, but I don't think it's positive enough to keep your machine steady against cutting forces. I haven't tried it myself, though, so I can't tell you it won't work for what you want to do.

[Devastator]

You'll get some bounce from the belts on anything but light cutting forces. And as mentioned, gantry needs beefed up, better router, not plastic.