CNC Control Box Part 1 / Layout ABS Enclosure NVR Switch EMI Filter

In this video I’m going to start building a new compact CNC control box for the latest CNC machine that I am building. And in particular, the thought going into laying out components and powering for this 300mm wide, 400mm tall and 200mm deep abs plastic electrical box. If you haven’t seen the machine itself, I’ll link to that video now in the card and also in the video description, and for the rest of you who are remaining or have returned I present you my externalised internal monologue.

I’ve already positioned the power supply units in here but I still need to mount these. And it does come with a galvanised steel backing plate which means I can earth everything. It’s also IP rated – I think IP 65 or 55. It has this gasket here but I have to admit it pretty difficult to open and close these. My plan is to have the power coming in at the top, to have an NVR switch at the front and all the controllers and relays and stuff at the bottom. And to probably put the glands for the stepper motors and limit switches either at the bottom or one of the sides. Probably the side away from the hinge of the door makes sense. So really it should go around that way. I’ve got my relay module there, and round here I’ve got some of the barrier blocks. I think I’m going to put some standoffs in here and mount these so the cables come around. Hopefully it’s not too tight. Or place the buttons here. I have bought some 24v momentary buttons with LED lights in them, so it should look pretty cool although all that said could put them on the top. I’m not sure how it would work out with the spacing just yet coz I don’t have the NVR switch and the one I was looking it was quite big (think I fell asleep while editing) five or six buttons here maybe keeping it at the front is the way to go.

I’ve just crimped all these wires onto some small pink boot ferrules using this thing here. It’s really useful. I also have to think about what I want to do with the flood and mist control. Where are they going to go? In fact I really don’t know. Whether I’m going to have another box like this with a frequency drive inside and how that connects to these terminals. The difference between this controller and the one I was using on the original machine is that it has a 0-10v terminal and a PWM terminal which is 0-5v. So in theory I could have one going to VFD drive and another which goes to a laser. I think I’ll probably will. I know the new or latest version of the phoenix controller is going to be different to what I’ve got and I think it will have a set up like this. But either way the most important thing is the relay module board and interfacing between all the inputs and isolating the inputs to be more specific.

I’ve already planned the wiring before the enclosure arrived – so I’ll be mainly following instructions I’ve drawn up for myself. Those will eventually be available on my Patreon page but in the following video I’ll take a little more time to talk about what I’ve done. This video will focus on my rambling thoughts plan the layout.

First, I’ll need to layout the components including the power supply units, and mark and drill the mounting holes. The backing plate will later be earthed which will provide safety in case of shorting, and help shield the components from electrical interference.

Oh I landed that one pretty good.

Making my enclosure so small is going to be tricky – as it’s hard to imagine how things will fit and the best process of assembly. I can imagine if I make a mistake, forgetting or needing to replace something dismantle will be like going backwards in time.

Oh it closes. That’s the most important thing I guess. I still don’t know what I’m doing with the VFD. I probably should buy another one these (boxes) and place the VFD in that. But I’m going to double check that it can fit in here. It looks tall. Yeah that’s too high. Maybe if I take the… this VFD is just too big but I know you can get a miniature version from Banggood so maybe I’ll do that and get another enclosure with this to one side, keeping them separate.

I’m going to draw on the enclosure where I think some of the components will go. The NVR switch will go over here and the power in gland here. I want to have the buttons here, so this will be the hard stop for the Arduino. This will be Cycle Resume, Feed Hold, and this will be the GRBL Soft Stop. And this side here probably the limits somewhere. And I’ll probably have the cable for the door switch coming out here. At the top I’ll have the probe. Maybe I’ll have the panel mount for the laser and another one that goes to the VFD. If I do have one going to another enclosure that’s how I’ll send the signal out. This side here are the stepper motors cables. I’ll probably have another button which will be the Pi off button which will connect to the terminals on the raspberry pi or orange pi – I might get an orange pi. And when it’s pressed it will run a command which will shut that down. And then I’ll probably need a couple USB for the mouse and keyboard and HDMI for a screen. There’s a lot going on there.

I’m still not sure about the onboard computer. I’d like to try install and set one up but it may be easier to connect the machine to an external laptop or pc. That stage of the build will be an entirely separate video. Anyway to give me some versatility with this machine and because I’m not a fan of water-cooled spindles, I’d like to wire a plug socket to a relay so I can control a hand router through g-code. This will also negate the need for an expensive CNC spindle, and accompanying frequency drive.

I’d also would like to add a no-voltage release switch to the enclosure so if the power fails the entire machine turns off, and remains off if the power turn back on.

I’m not sure if I’m going to have enough space for where I want to put it. In case there’s not enough clearance for the power supply units what I may end up doing is 3d printing a standoff for this so that it’s a little bit raised. I also think I’m going to change it from the left side to the right side so that the wires don’t stretch too far across.

Because the NVR switch uses an electro-magnet to keep the connection closed – and the electricity flowing to the internal components I’m going to also add an in-line EMI filter between the switch and the power supply units to prevent any unusual behaviour from occurring.

I’ve not go much space but that’s a diabolical cut out. No ones going to see it anyway.

I don’t have the right size glands for the cable I want to use for the power… but for now what I’ll do is just… Drill a hole, wire it up and add the gland when one arrives in the post.

I’ll wire the incoming power and neutral cables to the NVR switch, and then down to the EMI filter. I bought the NVR switch from Axmister tools and the EMI filter second hand from Ebay.

Luckily seeing as I forgot to measure the EMI filter and that arrived after I assembled the power supply units. I had just enough space to bolt the filter to the back plate, just above the power supply unit.

In my previous controller I use a contactor unit which ran to individual on and off buttons. The method I’m using now is a little easier to do but contactors have the advances of being able to use lower voltages to start and stop high power motors – they also make better clunking sounds when starting and stopping. I should also make a note that you will need to use the right gauge wire for the power consumption, and that there is a direction with which to wire the filter and NVR switch, so make sure you read the instruction and follow any diagrams for those.

I twist the ends of the wires with great finesse forming hurricanes of copper strands. Each a foot landing in its own insulated forked ferrule, the perfect utensil with which to feed electricity from and to the no voltage release switch.

It looks pretty neat. I’ll just demonstrate this working one more time and you can see the lights on there. I’m just going to turn it off. And the filters at the top there so that should help reduce any EMI interference from this section working it’s way in that although this is quite close to the power supply units. It does feel like the off buttons a bit funny.

I suspect this might be normal because of the mechanism of the switch, but If you happen to have the same one, I’d be curious to know if yours does the same thing. Anyway that was the easier part of the build – and many of those illustrations on the outside of the abs enclosure will undoubtedly change, so stay tuned for the following videos in this new series.


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