Building a Small CNC Machine
What do you need to build a small CNC machine?........
The answer can be broken down in to a few main components:
1) Computer Control
2) Electronic Drive Components
3) Non-Drive Electrical components
4) Mechanical Parts.
5) Works parts, tooling and other consumables
This Page Under construction......
The Computer Control
In the most general terms, this can be anything that can generate STEP/DIR signals (or PWM signals for Servo based systems, but we will focus on stepper systems here) based on a user input program. The program is typically written in G-code, though other file formats could be used depending on the CAM program used. Other type of coded programs include DXF, BMP. The coded program can be written either by hand or generated with a CAD program such as BobCad or AutoCad. In most cases the STEP/DIR pulses are generated by a PC running CAM software such as LinuxCNC, Mach3, TurboCNC or others, though embedded microcontrollers can also be used to generate the pulses. The typical CAM program like LinuxCNC will read a G-code file generated by the CAD program and issue STEP pulses out the PC Parallel Port.
So the first thing you will need is a control like a computer running software such as LinuxCNC
Electronic Drive Components
The Electronic components accept the STEP/DIR pulses from the control, and convert them in to electrical signals that can move a motor. The component train from computer control would be:
Control Output Port ->
Port Signal Extension Cable ->
Stepper Motor Drive Unit ->
Cabling from Drive to motors ->
Stepper Motors.
An example of a complete Stepper Motor Drive Unit would be the box shown here:HERE
Non-Drive Electronic Components
This can include limit/home switches, relay drives to control coolant pumps or spindle motors. Most often the interface for such I/O would be a Break-Out Board (BOB) that attaches either daisy-chain with the drive board to the main PC parallel port, or to a second parallel port in the PC. Additionally I/O could be controlled through various I/O such as serial ports, CAN bus, ModBus, Ethernet, USB, or other proprietary systems.
Mechanical Parts
This is the actual CNC machine itself. It should be CNC ready, meaning have motor mounts for the size of stepper motors being used, flexible couplings between the motor and the machine screw.
Works parts and consumables
Includes the work (blocks of aluminum, wax, wood or whatever other material will be processed). drill bits, end mills, saw blades, coolant, hand de-burring tools, work holding equipment such as clamps and vises....
