Going to build a circuit board CNC router

[metron9]

Hi, I'm Mark. I need some help on the design of my new CNC. Never made one before.

I will receive a new gecko 540 , power supply and stepper motors (495 oz) on Monday. About 3 years ago I tried making a simple X table for doing doming so I had a computer set up with mach2 and a full step board (I still have) from Stepper3.

I bought three linear slides, they have NSK ball screws and Thomson ball slides. Not sure who made these though. Last night I tracked down the three sensors they each have and found them to be OMRON TL-W3MC, the sensors alone cost 60 bucks each so these units must be pretty accurate.

Not sure why they need such expensive sensors if they are just e-stops. There are two on one side about 1/4 inch apart.

My question is how big do you think I should make the table. I plan to have a fixed spindle using one of the slides for the Z access. I plan to put two of the slides on top of each other to make the XY table.

The small table that attaches to the ballscrew is 5 3/4 x 4 3/4 wide. The slide moves 11 inches (1 turn is 1/4 inch) The 5 3/4 in parallel to the screw. They weigh about 10 pounds each.

As I don't know much when it comes to physics I don't know how big of a table I should put on the slide should I stay at the size of the existing plate or is there enough stiffness to go bigger.

The two ball berring slides that ride on the rails are 3 1/2 inches.

The second question is should I make the XY table using two of the slides or should I make a X access table with one and use two for the spindle?

I think similar ball slides cost over $2000 each but I am not sure I only paid $60 bucks each for them from craigs list, they were pretty dusty when I got them. A friend of mine with a bridgport is going to machine a shaft and keyslot that will fit the ends of these screws, they are 5/16 with a .125 key and i can't find any stock shafts that will fit. He will then bore the lovejoy to fit 5/16 as I can't find those either. I bought the motor connectors as well as the motors and gecko online at keling.

Any input appreciated.

[pminmo]

Make it no bigger than you need.