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CNC BUILD PROJECT
Total cost was around $200 I went a cheap weak motor route because I believe that spending $2000 on a home built machine has many of the same limitations as the cheaper. This build succesful tested a working concept that could be modified in the future.
- 100lb drawer slides from home depot
- small stepper motors from spark fun(3) http://www.sparkfun.com/ 200 steps per revolution $14.95x3
- easydrivers version 4.4 from sparkfun $14.95x3
- old parallel printer cable
- Mach 3 software
- harbor freight router
- 1/4 -20 lead screws with coupler
- brass plate for mounting motors
First step easy drivers and motors.The easy drivers and motors I find fairly weak and will skip steps when any load is applied to brake the motor. I defined the speed of the motors as 2.7 inch's per minute (4000steps/inch)=(54rpm) in order to eliminate skipped steps
(you can pinch the motor shaft with your fingers to stop it)
Too hot to touch the chips on the easy drivers reaches 155°F which is pretty hot for only 0.33ma.
3 motors and 3 easy drivers will cost around $90 from spark fun the set up is fairly weak but is cheap when considering larger motor setups are around $500
The Motors were wired [a][b] Red, green,Yellow,Blue
it is important to recognize the pairs A and B red,green and yellow,blue which will make the motor resist turning by hand when either of the pairs are connected ie.(red,green)
the default 1/8 step built in the easy drivers reduces torque of the motors I removed this feature by grounding the ms1 and ms2 pins
the 3 easy drivers/motors are hooked up with a 12v 1amp ac adapter plug
This was a printer parallel port cable completely taken down just to the pins using a razor blade. I had to do this because printer cables are not Straight through and the wires are not directly related with the pins I needed. a soft resin/rubber may be all over this parallel port your just going to have to clean it out or find a straight cable.
Parallel ports have 25 pins 8 of them are output pins,the step and dir for each axes must be wired to any of the pins 2,3,4,5,6,7,8,9
I originally tried my best to avoid using a parallel port by using an arduino uno rev3 but this was unsuccessful. You could use a cnc dedicated circuit board driver if you really dislike old computers but this will increase the price.
Assuming you have an old computer with XP and Mastercam installed and that you checked out the manual for installation instructions you have to confirm the address of your newly wired parallel port
go to control panel>system>hardware tab>device manager
The hexadecimal number mastercam wants is 0x378 this was pulled from 0378-037F found in the device manager and may vary for your system
Motor pin outputs are defined by how they were wired and step port/dir port changed from 0 to 1 which is the port number where 0x378 was entered
dir Low active will reverse the axis direction if it is needed
Explore the program and go through the config settings to make sure nothing was missed such as the motor tuning steps per inch
Congrats if everything was setup correctly you should be able to jog the machine and begin running code.
My machine is relatively poor performing at 2.7inchs per minute and has a working area of apprx 5inchesX10inchesY8inchesZ.I simply appreciate the learning experience for $200 dollars and will put up with the machine quirks considering the non demanding type of usage of the machine.
Below is a spindle clamp part made of clear pine it took 2hours of run time and the room got a little smokey the center circle/router is ~2.52 inches in diameter.
The part is resting on a drawing made with a bic pen. while testing the machine I hand wrote some code that took 33 minutes to complete 4x4inchs overall size.