CB CNC Part 12 / Powering PSU’s, VFD, Stepper Drivers & Control Board

In the previous video I assembled the enclosure and mounted all the major components on an aluminium panel. And in this video I will finish wiring the PSU, VFD, Steppers Drivers and control board to their relevant power sources.

The first thing I need to do is make a mounting panel for the on off switch and the emergency stop. I was planning to do this on the CNC machine, but it will be a lot quicker for now to just make these by hand. I will file or drill a small notch on the edge of the panels to clamp them in place, between a machine screw and nut.

Ok I’ve cut out this bit of Perspex, it’s an opal light box acrylic. It’s the same stuff that I used to do the blade runner lampshade so it’s matt on one side and glossy on the other. I’ve decided to use the matt side and I’ve mounted the two components. The on and off switch and the emergency stop.

I may end up using clear acrylic in the end if the innards are worth showing off, but I also like the idea of these opal panels being back lit by all the LED’s from within.

I’m now fitting the gland which will brings power into the enclosure.

You can see a little notch there, that I’m just using to hold it in place for now.

I’ve gone and wired everything up as I had done in part 9 but ran into problems.

Ok so I’ve just turned the power on and the light is on. I’m just going to flick that (breaker) up. Ok I’ve wired something incorrectly. Ah sheet.

I thought I was going crazy again. So I bought another two switches. I got a refund for the one I had before and they are all the same even the ones with the different face to them. And I thought maybe I’ve completely misunderstood this. Maybe if I kinda google electrical contacts. Normaly open contact is open in a non conductive state. So this one here, the brown side, should not make a noise when I touch them but it does. So I’ve gone and wired this back up thinking the other ones were correct, without actually checking them. Again I didn’t even take my advice from the previous video.

The designer must have decided to put labelling on the plastic moulding on the switchs, but failed to mention this to whoever was assembling. That’s my theory anyway. The E-stop doesn’t have any labelling so you have to use the volt-meter to check which terminal is normally open and which is normally closed.

Once I was happy with the wiring between the breaker, contactor and switches, I began crimping the ends of the wires with forked ends. The blue ones have a larger inner diameter hole, and can be used to crimp two wires together while the red ones are for a single 1mm wire. This method of terminating the wires looks neater and should also prevent flakes of copper dropping off into the enclosure – in case any break loose.

I need to screw the barrier block down now.

I had to screw this terminal barrier block down to the panel mount while other components were in place. This wasn’t ideal and I hope I haven’t made problems for myself to come. I’m going to use the block to split the power, neutral and earth wires over six terminals – making it easier to access.

If the terminal crimp is a bit too long to get into the terminal what I do is bend the metal a little bit. That normally means I can feed that in.

In retrospect this entire section would have been a lot easier to install had I got terminals and an EMI filter which could fit onto a longer din rail.

So I’m just going to put the EMI filter in now.

The spacing in this section is quite cramp, so I had to line up the terminals on the EMI filter against the slots in the trunking.

I think it’s pretty clear I am not an electrician. If you are in doubt about anything I think you should talk to someone who has a qualification. I know there is a trend at the moment of sort rejecting experts but the truth this is just one example you do it at your own peril, quite frankly.

I was going to put shielding on this and I went to have a look at what other makes have done and noticed they didn’t use shielding on the power cable coming in, so I’m going to ignore that part.

The EMI filter is fitted between the power and neutral wires coming out of the contactor unit, and then towards the power input on the VFD. The earth on the EMI filter is wired to the terminal block.

I just wired the power and neutral to that EMI filter. I’m just going to pop these into the appropriate block. The earth is already going to the barrier block.

I had found two earth terminals inside the VFD, which from future inspection were connected to the aluminium heat sink at the rear of the VFD. I’m not sure if this was the correct thing to do but I connected the earth wire from within the VFD to the barrier block as well.

I probably could have found a barrier block and an EMI filter that could have fitted on a din rail – which would have made this a bit easier to space out. I think it is a little too one side but it works so that’s a relief. A massive relief.

I am now wiring power to the final components within the enclosure. I already soldered the DC power jack for the control board in a previous video, and have now cut this to size, running it from the 24v power supply via the E-stop’s normally closed switch. In case of an emergency I can press the emergency stop, which opens the contact and stops power reaching the control board.

I also wire the 36v DC power from another PSU to the stepper motor drivers.

So I just put two wires in, onto one terminal.

I use blue forked crimps to connect two sets of wires from one set of terminals to power two of the drivers. So all four drivers use two sets of power and ground terminals on the PSU.

Lets turn this back on again. The green light are turning on. 1,2,3,4,5,6,7… and 8.

So that’s power coming into all the major components. The variable frequency drive, all the power supply units, the drivers and the control board.

In the next video I will wire the stepper motor drivers to the aviation panel mounts, and the control board. Everything seems to be coming together well, but I have to admit deciding to only use two machine screws to hold the external panels mounts means there is a little flex there. I can’t change the enclosure now, so I’ll have to think of a solution to reduce this in a future video.

Anyway if you found this video useful and or enjoyable please sacrifice a thumb, and if you can financially support this channel please check out my patreon page, the link to which can be found in the description. There subscribers can access additional material and in the case of this part of the project, a diagram of the wiring so far.

Thanks again for watching.



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