I am in the process of building a Plasma CNC. It will be 40" by 28" --the size of the street grate that I found. I have bought linear rails and blocks and am about to build the gantry. I am deciding on using the material that I have which is 1" by 2" rectangular steel tubing or going with aluminum. Either way, I am looking for any inputs as to the mounting of the linear rails on the sides of the tables: on the horizontal or on the vertical.
Also, screw drive or rack and pinion. Screw drive takes the motor weight for the X axis off of the gantry but might cost more initially. Rack and pinion seems easier to deal with and might be better if I need to have speed.
Any ways, here is a pic of the table: