Final Project - Design Concept
System Overview
The CNC router consists of the following subsystems:
Computer: CNC software, machine control software and USB interface.
Embedded controller board (on CNC)
Stepper motor drivers: x-axis, y-axis and z-axis driver boards
Stepper motors: x-motor, y-motor and z-motor.
X, Y and Z limit switches
DC power supply
The overall system block diagram is shown below.

Before I can begin building the CNC router, there are a number of factors that I need to consider:
Step 1: Key Design Decisions
Identifying the right design: mobile bed vs gantry
Required cutting area
Space available
Materials used
Tolerances
Construction methods
Budget
Step 2: The Base and X-axis Frame
Full supported or partially supported frames
Solid or aluminium profile
Different frame designs
Step 3: The Y-axis Gantry Design
Different frame designs
Forces and moments on the gantry
Step 4: The Z-axis Assembly Design
Different designs for Z-axis assembly
Forces and moments on the Z-axis assembly
Linear bearing rails/rods
Plunge arm design
Step 5: The Linear Motion System
Design of linear motion system
Shaft & bushings vs rails & guide blocks vs rods & bushings
Step 6: Mechanical Drive Components
Choosing right drive components for the design
Lead vs ball screws, radial & thrust bearings
Belt & pulleys
Motor coupling & mounting
Availability & cost
Step 7: Choice of Motors
Stepper vs servo motors
Motor sizing, NEMA standards
Choosing the right motor for the design
Step 8: Cutting Table Design
Different cutting table designs
T-slot vs perforated vs cutaway beds
Vacuum table
Step 9: Spindle Options
Types of spindles: dedicated or dremel
Mounting & cooling options
Chip load, cutting force & feed rates
Step 10: The Electronics
Choosing electronics for the CNC
Control panel, wiring & fusing, buttons & switches
MPG's, jog wheels & power supplies
Step 11: The CNC Controller Options
Choosing controller board
Choosing motor driver boards
Sizing power supplies for CNC
Communicating with the host computer
Step 12: Selecting the Software
CNC related software overview
CAD & CAM software
NC controller software
gcode, json, stl or gerber support
Free vs commercial software
Phew! Loads of sweat & nervous chewing of fingernails... That's a lot of stuff that need to be considered when designing a CNC machine. I hope to make some headway over the next few weeks, so that I can begin working on some of the subsystems as we progress in the course.