Last night i was modeling a bit in Solidworks 09'.
Base Parts list:
80/20 15 series 3060 (2x24" pieces, 2x30" pieces)
80/20 15 series 4417 18 hole 90 degree brackets (4 pieces+hardware)
80/20 15 series 2531 45 degree 12" brackets (4 pieces, with hardware)
Nook Industries NH-EA series linear rails and blocks (2 rails, 4 blocks)
1/4" 6061-T6 Aluminum top with 1/4" tapped hole pattern (3"x3" i believe).
Render-2 Just a view showing the aluminum top.
Render-3 Top turned to glass instead of aluminum to show inside of table.
Render-4 Top turned to glass instead of aluminum to show inside of bracket.
I just wanted to get a feel and a idea of how its going to come together, parts will change as well as the overall size of the machine. I just want to mock up a initial machine in solid works to get the feel of the overall general gantry design, before i get too specific.
I was going to mount the linear rails on the sides of the base, but by placing them on table top the load is distributed symmetrically on the rails and bearings, overall easier to align them parallel to one another, and the force is distributed straight down through the plate compared to being mounted to a flimsy machined down fin, between the T slots (via the side). Disadvantage to this design is having to make the table a bit larger, because by top mounting the rails i loose working space. I believe for overall accuracy top mounting the rails would be the best route to go, and i don't mind making the table a bit larger to accommodate them.
I would like to use a dual ball screw setup so i get absolutely no binding, and the force and motion will be distributed evenly to the moving gantry. I may make the table wider and mount a single ball screw on the outside of each linear table rail. Then i can mount the Servo/Stepper in the rear of the table bolting small gears to the servo/stepper and both ball screws. Then link the entire system together using a belt, chain, or some other form of mechanical linkage (whichever is most accurate).
Tonight i will try and accomplish placing ball screws on the table and possibly making a rear stepper/servo mounting perch.
I would love for any kind of positive input! This will be my first cnc mill and im trying to do it right! Thanks!