CNC Machine Build

This page summarizes my notes on building a CNC machine.

I've built 2'x3' machine described here. I like the design because it's modularized to 80/20 aluminum T-channel extrusions. I built the machine exactly as shown in the plans.

Suppliers:

• CNC Router Parts (steppers, drivers, linear carriages, misc. hardware)
• Fine Line Automation (rails, misc. hardware)
• MSC Supply (misc. hardware)
• Automation4Less (80/20 extrusions, cut to length)
• Linux CNC (control software)

Both Ahren (CNC Router parts) and Nate (Fine Line Automation) have been super responsive and helpful.

Here's my full bill of materials (BOM).

Contents 1 Build Notes 1.1 Emergency Stop 1.2 T-Slot Table Top 1.3 Setup Probe 2 Errata

Build Notes

Initial build pictures, with a small temporary table installed:

Overall view	Cross-gantry drive
Z-axis drive	Another overall view
Z-axis drive and router head
Back of gantry	Rear view of gantry

Emergency Stop

After getting confused about my Z-axis reference and cutting a slot in the table, I implemented the emergency stop switch:

The mount was fabricated (on the machine!) out of 0.221" plexi. I got the switch on eBay: $10 new.

This is currently connected to the DISABLE/E-STOP input (position 10) on the Gecko G540 driver. Alternatively, it could be connected to one of the G540 input pins and configured as the ESTOP input to EMC2.

T-Slot Table Top

After I got the basic machine up and running, I built a T-slot top. I used Incra 48" T-Track spaced on 6" centers. The substrate is 3/4" plywood with a 1/2" MDF top layer, screwed down (easily replaced after wear or gouging).

The table is attached to the aluminum extrusion with 6 recessed button head cap screws, and 5/16" T-slot nuts. It slides in and out from either end.

Basic construction	Finished view
In use

If I were doing it again, I'd consider:

• Shorter 36" T-track (the working area of the machine)
• The Kreg track, which is slightly thinner and has countersunk holes. The Incra track screws are not countersunk, and the screw heads catch a lot of sawdust and debris.

Setup Probe

TBD

Errata

• When using the 5-start ACME nuts from CNC Router parts, make sure you get the recommended leadscrew from McMaster-Carr

• The PB-0001 fastener bundle from Fine Line Automation is missing two 5/16-18 3/4" SHCS (for attaching the cross-gantry motor mounting plate). The screws are also missing from the CAD drawings (as of Oct-2009)

Plans:

• Use the latest plans from Fine Line Automation's Web site, which include PDF drawings of how to cut and drill the 80/20 extrusions. The plan .ZIP on the CNC Router Parts site is one rev old.

• The MSC part numbers in the Excel spread sheet files for Powertrain components, Force Transfer are incorrect. Also, the LoveJoy motor coupling scheme has been superseded by the zero-backlash coupler from CNC Router parts.