[Thinwater]

I just bought the metal for a new 20" x 36" build. I am looking at using 1" solid, hardened rails from McMaster and matching ball bearing trucks. Will these be thick enough to support the gantry over the 36" length?

What would be the recomended size for the 20" axis?

The frame will be the usual 80/20 with 1/2" thick x 5" high endplates. The gantry will be 1/2 plate and 80/20. The Z will be milled from billet.

If I need to go to supported rails I will or will use thicker round rail if it is cheaper.

Does anyone recomend a good source for a C3 or better ball screw and nut assembly they would be the correct size for this build?

I will be using my Haas VF-2ss to make the parts on. Picking out the correct screws rails and bearings is the only issue to work out.

Thanks in advance for any info.

[HereinCS]

I'd go with the supported rails. There is always some flex with end-supported rails. Since you are looking at c3 screws, I'd imagine that you are building with very tight tolerances. C3 screws are very expensive. I bought some c5 screws from here, at a very good price.

Since you are building such a high end machine, do you really want round rails? I heard, and I'm no expert, that the Hiwin, NSK, etc square rails are much tighter tolerances.

[HereinCS]

Here's the c5 screw for your 36 inch axis.

[Thinwater]

Thanks for the great link. They have the proper supported bearing for the same money McMaster gets for round shaft and bearings.