Step #1: Mini CNC specifications
The working area of the machine is X=450mm (approx. 17.5 inch) and Y=250mm (approx. 10 inch) and it can mill parts as high as Z=110mm (approx 5 inch). The maximum milling speed on X an Y axis is 2400mm/min. and on Z axis is 1800mm/min. The resolution of each axis is 1/50 or two hundredths of a millimeter and one motor revolution on each axis results in 4 mm of movement. The router used is a Kress 1050. The number of parts used for building this mini CNC machine is 42, excepting screws and nuts, and the total cost is $1200.19.
Step #2: Required tools and skills
For this project you will need to have a set of screwdrivers and a set of hex keys or Allen keys, a drill for some extra holes, metal-cutting saw to cut some custom parts, soldering station or soldering gun to join the wires so they'll have good conductivity, and a multimeter. You should have knowledge of basic electronics, how to solder and how to use a multimeter.
Step #5: Mechanical components - shafts, bearings and leadscrews
- Ø20mm precision steel shafts for X axis (cut from 1 piece of 60-inch=1524mm shaft): 2 pieces, each 600mm long (cost: $54.00);
- Ø16mm precision steel shafts for Y axis (cut from 2 pieces of 30-inch=762mm shaft): 2 pieces, each 390mm long (cost: $29.95);
- Ø16mm precision steel shafts for Z axis (cut from 2 pieces of 372mm shaft left over from the Y-axis shafts): 2 pieces, each 300mm long (cost: $29.95);
- Machining the precision steel shafts: 6 pieces (cost: $25.00).
Step #7: Electronic components - motor controller
- The stepper motor driver used is a unipolar 4-axis driver for 5A/phase motors. Cost: $82.50.
- Electrical properties:
- Input Power: 20-40V DC.
- Stepper motor drive current: 1.5A - 5A/phase.
- Compatible stepper motors: 2 or 4 phase, 6 or 8 lead stepper motors, 5A max.
- Dimensions: 18 x 12 x 6 cm (L x W x H).
- This board allows you to control 4 stepper motors, as well as receive input from two limit switches per motor and from an emergency-stop button, and it has a relay interface for spindle motors.
Step #8: Power supply components
The power source contains one 600W toroidal transformer (cost: $76.60), one 50-amp rectifying bridge (cost: $1.90) and one 20,000µF capacitor (cost: $7.99). Total cost: $86.49.
Step #9: Motor controller case
For the motor controller case I used an old Keithley236 source measure unit. I have removed all the guts of the old thing to make way for the new motor controller and power supply.