It was a lot of fun building the mechanics of my machine, but I feel much more in my element tangled in a sea of wires. If you are unfamiliar with how this type of system works, what components are involved, or just have no clue what’s going on. I highly recommend reading the Mach3 users guide, Mach3 is a very popular CNC control program by ArtSoft.
The manual actually goes way beyond the scope of the software and discusses many different aspects of the electrical design and layout of a machine. Even if you don’t plan on using Mach3 to drive your machine it really is a worth while read, if you do plan on using Mach3 its a required read. Hit the link below to get started.
Mach3Mill Users Guide
I decided to use my old desktop PC for a control system, A AMD Athalon XP3000+ with 1GB DDR400 and an ATI X800GTO. Its probably a little overkill for this application but its the most stable machine I found and I cant think of a better use for the computer right now. Running the Mach3 driver test even in 100Khz mode results an amazingly consistent system response time even while monkeying around a bit. I would very highly recommend formatting whatever computer you choose to test and install a fresh OS before testing. Do not connect the network interface or install any windows updates, just format, install necessary drivers, mach3 and test. If you have good results proceed with configuration of the computer, installing antivirus, updates, networking, etc. However keep in mind the more services your computer is running the more likely you are going to get variations in system response time, this will be more noticeable on older computers. The secret (its not really a secret) to a good stable CNC computer is a clean CNC computer.
Mach3 does has a driver watchdog that will send an E-stop command to the system if it detects the response time becoming unstable. However this is still not something you want to have to deal with in the middle of a job. After I got my system properly setup and tuned I made a ghost image of the hard drive, so as to make for easy fixing when I mess something up.
Most hobby CNC setups involve a remote enclosure that houses a DC power supply and drivers for whatever stepper or servo motors are installed on the machine. This enclosure then connects to the controlling PC via DB25 parallel and to the machine via a separate wiring harness. I wanted to integrate the two systems as much as possible, installing the DC power supply and motor drivers in the PC case. I chose a used(beaten) cooler master computer case because of its heavy construction, removable motherboard tray, and because its all aluminum . Lets go over what has to fit inside.
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