This is just a copy of some of my comments from the Thingiverse page that I thought might be useful:
It is called 1" EMT conduit but it is actually .93" outside diameter. I used Home Depot but Lowes should be the same thing. http://www.homedepot.com/p/Allied-Tube-Conduit-1-in-EMT-Conduit-101568/100400409 http://www.lowes.com/pd_72715-1792-101568___?productId=3129555&pl=1&Ntt=emt+conduit
3/4"-see comments below
These are zinc coated steel and are very stiff. The bearings work a bit roughly at first, then the zinc coating rubs off under the bearing after a while making a nice smooth surface. I just ran some hand edited G code that moved the axes back and forth until the zinc wore down. Then I sanded them just a bit with very fine sandpaper to get the sharp edges off of the zinc “race”.
I used a regular pipe cutter with many rotations of the cutter for a cleaner cut than with a hack saw.
Thanks for the tips! Great tip about smoothing the pipe. Damn now I have to back to harbor freight for a pipe cutter - I was just there. I was wondering about the edges after the cut.
Correction to the dimensions and link:
It is called 3/4" EMT conduit but it is actually .922" outside diameter and ~.82" inside diameter. I used Home Depot but Lowes may be the same thing (measure it first before buying).
These are zinc coated steel and are very stiff. The bearings work a bit roughly at first, then the zinc coating rubs off under the bearing after a while making a nice smooth surface. I just ran some hand edited G code that moved the axes back and forth until the zinc wore down. Then I sanded them just a bit with very fine sandpaper to get the sharp edges off of the zinc “race”. I used a regular pipe cutter with many rotations of the cutter for a cleaner cut than with a hack saw.