I am 13 I have always wanted to build a cnc machine but because inexpensive parts are hard to find in Canada I have had trouble trying to build a decent cnc controller. The purpose if this Instructable is to show that anyone can build a cnc controller using an old scanner. The scanner I used was an old OpticPro scanner. I had previously extracted the stepper motor and experimented with it but not considered it for a cnc controller. All of the controllers on the Internet had a large number of expensive transistors or were ridiculously complex. I finally stumbled across this controller and realized I could build it. By reusing the parts from the old scanner and making the case from recycled cardboard, I am cutting back on my impact on the planet. Also, because this controller is so simple, it only needs one power suply, so, it only needs 1 12 Volt (for both the logic and the motors), instead of 1 5 Volt (for the logic) and 1 12 Volt (for the motors). This saves energy, especially when you run it for a long period of time.
If you don't already know what a cnc machine is, it is a machine that uses special motors called stepper motors to moce an object a percise distance. The difference between a stepper motor and a regular DC motor, is that stepper motors "Step", not spin. if you don't understand, refer to this artical. There are two types of stepper motors. There is Bipolar, and Unipolar. Bipolar motors have 4 wires. Unipolar motors can have 5, 6 and 8 wires. The difference between these two types of motors is that unipolar motors have 4 coil inside that, when energized in a certain order, allow it to step forward and backwards. This makes them easy to control and is why we are going to use them in this instructable. Bipolar motors only have two coils that can be energized in forward, or reverse. To drive a bipolar motor you need two H-bridges. Because of this, bipolar motors motor controllers are much more complex.
In the scanner:
For the enclosure:
For the controller
For the test rig
For the control computer:
Get Parts from Old Scanner
Remove Chip from Control Board
Install Control Software
Configure Control Software
You will see a screen that looks a little confusing. Do not worry, it is not that bad. Press tab until you get the box that says"Drive Type". Press the down arrow to select 'Phase. Press tab again to select the Scale box. If your computer has a mouse in dos (mine does not), click the calc button. If yours is like mine, you can simply run the program off a computer running Windows XP or Vista by double clicking on the TURBOCNC file. Then, follow the above steps.
To use the calculator, you must find the number of steps per revolution that your motor takes. Google your motor's part number and look for how many degrees per step it takes. Then, divide 360 by the number of degrees per step to find your steps per revolution. For example, my motor turns 7.5 degrees per turn, so I divided 360 by 7.5 to get 48. Punch that number into your scale calculator. Leave the rest of the settings the same. Press ok, and then copy the number in the scale box to the scale box on the other computer. Next, change the value in the acceleration box to 20, as the default 2000 is way too fast for your system. Change the value of the start velocity box to 20, and the value of the max velocity box to 175. Change the value of the fast jog box to 175. Press tab until you get to the "Last Phase" option. Change its value to 4. Press tab until you get to the first row of x's. Copy the following into the first four boxes:
Build a test axis
Place the two rods through the holes on the line. Screw a small screw into your rods to keep it in place. Slide your second piece of wood onto your rods. Mount your motor to the final piece of wood. It does not matter how you do this, be creative. I used two pieces of 1/8 threaded rod to hold mine in place. Now slide your wood with the motor attached to it on the other end of your rods. Screw the rods onto the wood. Slide your threaded rod through the third hole on your first piece. Screw your nut onto the rod. Slide the rod up to the second piece of wood. Turn the rod until it slides through the holes and up to the motor's shaft. Using aquarium air hose and zipties, connect the motor shaft to the threaded rod. To attach the nut to the 2nd piece of wood, I used various screws and nuts to hold my nut in place, but anything should work. Finally, cut a piece of wood the size that you want your stage to be. Screw it onto the 2nd piece of wood. Make sure that your stage is level. Mine was not, so I used washers as spacers. You have now built an axis for your motor.
Conect and Test Motor
To test it, connect your 12 volt 300ma dc adapter into your barrel jack. Then, connect your DB25 port into your computer. Open the attached program in TurboCNC to test your motor wire connections. When you are done testing and changing your connection you should have a fully working axis.
To test the scale of your machine, attach a marker to your machine and run the test program. Measure the line. If yours is 1 inch long, or close to it, then your machine is good to go. If it is off, check your math. If you have made it this far, congratulations, the hardest part is done.
Make the Enclosure
Now you need to cut your panels. Cut two rectangles that are 3 inches by 4 inches, 2 rectangles that are 2 inches by 4 inches and two panels that are 3 inches by 2 inches (see pictures). Now you need to cut the holes for the ports and plugs. Trace your parallel port plug on one of the 4x2 inch sides. Cut it out. On the same side, trace your dc barrel connector. Cut that out too.
What you do in this step depends on if you soldered connectors to your motor connection wires. If you did, mount your connectors on the outside of your blank 4x2 inch panel. If you just used wires, poke 5 holes. Now, using hot glue, glue all of the panels together (except the top one, see pictures). I chose to paint mine silver.
Make the Enclousure
Possible Uses and Conclusion
This Concludes my instructable. I hope you found it interesting and helpful. Feel free to modify my design and let me know how it turned out. If you liked my instructable, please vote for it in the Epilog Laser Cutter Contest.
To configure the program, follow to above steps, except when you go to enter the number of axis', enter 3. For the configuration, follow the steps above for the first axis, for the second axis, keep it the same as the above steps, except in the first four phase lines, enter the following:
For the last axis, follow the same steps of the other axis', only copy this into the first four phases