My base is bowing

[guru_florida]

Moving table design: I am using 1/5" 8020 extrusion and 25mm rails and, to my suprise, I am getting about 20-25 mil deflection in the center on 24" long rails.

Just an FYI for any other DIY cnc'ers...dont assume.

Its my own fault, I should have done the math than assumed it was already over-engineered. The spans are not sitting on the ground, they are suspended 1/4 inches off the ground by the plates on each end. This 1/4" spacing was meant for the base plate, but I haven't found the right size cheaply yet...but I guess its more priority now!

[KTP]

I think the next moving table gantry design I do will have a granite surface plate for the base. IMO you lose the gains from a fixed gantry/moving table if your moving table is mounted to a flimsy surface. Now to figure out if I can mill/drill holes in a ENCO granite surface plate with my 60 watt CO2 laser.

[guru_florida]

I am definately going to get that base plate on there. I am thinking .375 to .5" plate. I am going to do the math this time though.

How is that co2 laser working out for you? I would like to have a friend make me one soon. What kind of materials have you cut and thicknesses? Do you use a gas at the cutting point to enhance cutting power? Did you buy or DIY laser?

Obviously, you have my interest now!

Colin