The members of a Hacker/Maker Space, here in Atlanta, GA (Freeside Atlanta) have collaboratively designed a CNC Router. We post the design seeking input from this august crew.
This design extensively uses 2" x 2" (1/4" wall thickness) square tubing. Most uniquely, we mill the surfaces of the square tube and use it as Y axis guides/rails.
Design objectives:
1) Cutting surface of 4' x 4'
2) Sturdy -- able to withstand the unforeseeable abuse of a Maker/Hacker space environment: collisions with runaway autonomous pogo sticks and/or folk lifts, keg bowling mishaps, etc.
3) Simple and self-evident mechanical design for ease of maintenance and repair.
4) Low maintenance.
5) Keep the use of proprietary components to a minimum -- allow for several of the parts to be machined by the builder.
6) Achieve tolerances that allow (at minimum) for wood furniture part manufacture.
7) Keep the design plans Open Source.
8) Exchanging the router for a plasma torch is contemplated in the gearing/motor selection, but is not expressly included in the design.
Construction:
The table base, Y axis guide rails, and the broad expanses of the gantry will be constructed of 2" x 2" (1/4" wall thickness) steel square tube.
Because we have access to a mill, we will mill surfaces flat and use the square tube as Y axis guides.
Because we have access to a water jet, we will construct much of the gantry's frame fron 1/2" aluminum plate.
Drive systems:
Rack will be mounted to the underside of the Y axes' rails, and Ehren's (CNCRouterParts) "PRO Rack and Pinion Drive, Nema 34" will be fixed to the gantry.
The X and Y axis will use acme screw drive systems.