Cowboy CNC Machines & Real World Automation?

So as a side project, during the procurement lead times of my main project, I thought I would have a look into the CNC welder that has apparently been playing up at my work.

Keep in mind, I am the only electronic engineer employed at the company in a primarily mechanically based business. As a result, I have dubbed myself the principle, chief, senior electronic engineer of the company, how do you like my LinkedIn profile now!


The designer of the CNC machine built it in his garage and is interesting for three reasons.

• It is quite impressively complex for something built by one mysterious man.
• How well does it fair from an industrial automation best-practice point of view?
• How much work does it take to build one?

Anyway the designer went AWOL a while back, so it is up to me to figure it out from scratch... YES, time to get my hands dirty!
 










Noodle break: My face as I open the control cabinet for the first time.
 

This is my first time getting stuck into something like this, but I think I can say with confidence that it is perhaps not what you imagine when you say industrial automation, it’s a bit of a jury-rig situation but I think it gives it personality.

I love the computer terminal, oh XP how quaint. 

So it looks like for the most part it will set you back an old desktop computer with a custom PCI module, I was able to download the software for free on my laptop so at least you don’t have to pay for that.

The control cabinet is the interesting part and where wiring conventions best practices or even just color coding can make life a lot easier when trying to debug glitches (as you can see).

The PCI module will connect to the micro-controller in the control cabinet and has various low level Boolean controls that are easily flagged from the computer terminal, quite intuitive actually. Everything is 12v, hooray, at least that’s something I don’t have to worry about.

I expect for more complicated and rugged systems you would use a PLC but for what we are working with a micro-controller is more than adequate. The main problem with the machine is with the relays breaking, solid state components are a good modern alternative, such as opto-decouplers.

There are also no buffers used to drive the relays, after some quandary I realized that the power is grounded through the micro-controller CMOS outputs, clever but I wonder if the relays are getting enough current to run reliably? Well I guess that is the point.


Then it is just a matter of plugging an old welding machine or drill or laser… whatever you want, it can even be one of my favorite words… modular. 
The CNC bay might be a bit tricky from a mechanical perspective but hooking up the motors to the drivers looks very easy (these are all two-phase steppers).

Don’t forget those end switches.

Oh, a good application of when ingress protection is necessary and as expected in this very dusty environment, the cabinet is full of it... great!




What, this wasn't in the syllabus!

Behold not all programming is confined to C, Java, Python, Basic and Assembly! Sometimes life throws you a curve-ball and hits you with G-Code?!?

A CNC based programming language... actually this is pretty easy if you have annotated your code properly (thank you Mr.Designer) and I found a decent manual online.

Pseudo-Interlocks.

Now we are talking automation, is that a real interlock... no, never-mind everything is still live as I stick my head in this cabinet. Ohh, a red wall socket, I hope it isn't this cabinet that runs on 440 volts.

Oh home time already, I will continue tomorrow.

And so ends another mad day of indulging in what is essentially my hobby of tinkering, breaking and fixing (there is a fine line), perhaps tomorrow I will do something productive...