Hi Jay. Sounds like you have a good plan. If you need any help or advice, ask away!

You'll find a bunch of very helpful folks here, all willing to impart what we know.

Larry

 

It's funny how it works that way. And you just never know when you might decide to build a printer (or 3), a lathe, a vertical mill or a robotic arm - those extra screws might be handy. I have tons of extra hardware, but I'm retired and enjoy building things. I've got 6 mills (2 commercial) and 6 3d printers around here and quite a few I've given away to kids in the area.

It's worse than potato chips......

 

In that size, I'd not even think about belts. Maybe some super big industrial belt that would cost more than a ballscrew, but that's not a good idea in my mind. For 3000mm you'll need a 1 inch screw, in my opinion. I'm using a 1/2" screw on a 1500mm y axis and it's as small as I'd ever go with that. For double the length you'll need much thicker plates, bigger bearings, heavier frame. Making that jump in size requires a lot more engineering and moving away from aluminum to a steel frame. Some have done that size with aluminum and even wood, but I suspect that a honest report would be that steel would be better.

 

It seems like it would be a good built. What you gonna use for the working area. MDF or Aluminium.

 

Rack and pinion should work just fine too. Sorry I didn't mention that too. 1605 should do OK for X and Z - as far as that goes 8mm would work for the Z axis, unless you are hanging a lot of weight on it. I've used 2.2kw water cooled spindles on one up to 3ft long, but at that point there is a definite twisting of the gantry. I'm going to back my gantry with a piece of 3/8 x 3" steel flat to see if that helps. If not, I'm going to pull the gantry apart and add another 20x80 v-slot behind the gantry C-Beam.

Stretching out to 4'+ will only be worse and why I suggest a steel channel for the gantry.