[Tom Kay]

Hello All;

My first post on the forum. First, congrats to Art, who really seems to be making a lot of CNC users happy with is software.

I want to make a 4 axis router to cut wood, plastics and perhaps alum. Mainly I want to make wood propeller blades, 45" long. Hence the 4th axis.

To save money, I might use Acme lead screws and plastic nuts, preloaded for smallish backlash (not quite zero backlash as this causes plastic wear more quickly).

I want to use cheaper lead screws, say 1/2" diameter, but at 6 feet in length, stiffness becomes a real concern, especially if I load the screw in compression. By the way, this will be a typical gantry system, with 2 lead screws moving the gantry, as we've seen in many designs.

So here's my question: Is it OK to find a way to permanently load the leadscrews in tension to keep them from buckling under compression? Obviously the amount of tension preload that I "stretch" the leadscrews with would have to be greater than the max cutting force that I apply to them in compression. But has anyone ever seen this approach to using smaller leadscrews?

I might have to use a steel frame to take advantage of its stiffness if I permanently stretch the leadscrews.

Any thoughts?

Thanks, Tom.