CNC Control Box Part 5 / Frequency Drive (VFD) & Enclosure, Air Fans, Spindle Relay Module

In the last video I installed some under-gantry LED warning lights, prepared the wiring for a laser engraving module, and updated the Arduino bootloader to solve an unusual behaviour with the D13 pin flickering on and off, when the controller was reset.

In this video I’m going to install a pair of fans to aid air circulation within the enclosure, fit a 240v UK plug to the enclosure door which can be activate by the spindle enable pin relay, and finally install and wire a VFD into a separate enclosure which will power the router spindle.

I start by wiping off the diagram of possible connections for an orange pi board. I’ve decided that I’ll make that up either in a separate enclosure, so I had the options to still use my laptop.

To start with I fit the fans. I had to find 24v fans which was a little trickier. I think in retrospect I should have wired all the proximity sensors, LED lights and buttons to 12v DC but I start with 24v so I had to finish with it. The fan at the bottom of the enclosure pushes warm air out and the fan at the top drawers cool air in. The case is a little annoying as the seam along the centre makes it impossible to fit a larger fan. So I end up using 40x40x20mm fans – which will have to run faster to move a similar amount of air as a large one would.

I also found dust covers for the fans – which will help protect the components inside.

I soldered the fan wiring together and terminated those at the 24v dc power supply. When the power turns on the fans start automatically.

Ok I’ve just wired up the fans and I’m going to turn it on so you can hear how loud it sounds.

I also fitting this fitted the USB panel mount to the enclosure where I’ll be able to connect my laptop or dedicated external computer device to the controller board. I 3D printed the yellow surround for the panel mount to make installing a little easier and tidier.

I’m now fitting a 240v UK panel socket to the enclosure. This will received its power via the no voltage release switch.

I had to change over to the insulated blue female spade connectors as I can crimp two set of cables coming out from each terminal on the NVR switch. From which one pair of live and neutral goes to the EMI filter, while the other goes to the 240v panel socket with the live going via the relay module controlled by the spindle enable terminal on the control board. When the machine is off or idle the relay is in a normally open state and no power can pass, but when energised when the spindle enable pin is triggered by software, it receives powers. I could use this with an extractor or a typical woodworking routers. But for the purposes of this video I use it to power a laser disco light while performing a test drawings sequence. I’ll feature the drawings tool in an entirely separate video once the overall build is complete.

I’m just going to drill a hole out for the cables which will go to the VFD. I still haven’t decided whether to get another box like this and try squeeze this one in, or get another box like this and buy a smaller VFD and know it will fit. This one’s a little too big so I may have to take the top panel off, so it fits or potentially turn this on it’s side.

I’m now temporarily wiring the frequency drive to the controller to test the connections. Later I will place the drive in a separate enclosure with a detachable power and signal cables from the controller enclosure.

I’m connecting the spindle enable from the controller, via a relay on the output relay module to the X5 and Digital Common terminals of the frequency drive. And the 0-10v signal again in the same way to the AI1 and analogue common terminals – which control the spindle speed. In my previous machine I also connected the estop to another terminal which I had programmed to break the spindle and act as an emergency stop – but I couldn’t find LED backlit buttons with dual terminal inputs – so I couldn’t wire the hard and soft stop to a separate relay module and then on to the VFD.

Ok I’m now going to place the VFD over here, inside this other enclosure. And I’m going to make sure the panel is accessible from the outside and I also have a toggle switch so I can go between the VFD potentiometer and the Gcode PWM from the software. I’m going to take this stuff apart. I’ve already taken a photo. I think I can get it in facing upwards if I take this top panel off.

I’m drilling the opening for the power to come out from the main enclosure, which will be connected to the VFD enclosure with a kettle lead end.

I just cut out this hole for a kettle mount, so the power comes from the main section of the controller and ends in one of these. That gets plugged in and then the power can be fed to the frequency drive.

I may have to move the machine in future, and it would be difficult to do if I can’t dismantle it.

I’m now laying out the VFD display panel on the door so it is clear from the electronics within. I’ll just say here it’s quite tricky to cut ABS enclosure with a jigsaw because the cut line can re-melt and close the cut – it’s also very smelly so a vapour mask is a good idea.

That’s where I realised I placed the VFD in the wrong position and couldn’t lock the door… grrrmmmm,

I’m drilling the opening for the toggle switch. And after I fit that I place the ribbon cables to the panel display. You can buy ribbon cables and connectors fairly inexpensively, and all you need is a good clamp or vice to push the connectors onto the ribbon where you need.

Ok I’ve just done the wiring. I just got a bit bored of filming so I cut ahead.

I also had to re-programme the VFD – which I’ve written as an excel document to show the setting that I’ve changed. My frequency drive is an NfLixin. There’s not much documentation about this drive so I had to do this from scratch with a poorly written manual and a lot of trial and error.

Ok I’ve just taken the old CNC machine apart and placed the new one on the bench over here, with the main body of the controller over here and the enclosure that will hold the VFD just next to it. I now need to fit this wire in.

The last thing I had to do was wire the SY cable from the VFD to the spindle.

I’m going to have to place the hole a little bit to one side just because there’s a bit of plastic buttress or something in there, just to keep the shape and clip it together. And if I drill through that it might weaken it, and also I may not be able to get the locking nut on.

That silver thing in the enclosure is a breaking resistor for the frequency drive. These do a few different things, but the main thing is to decelerate the motor quickly. I can’t remember if there was a difference in breaking speed on the previous machine, when the spindle enable signal turned off and if the estop terminal on the drive was triggered. But I didn’t test this so there’s no point me talking about it.

I made sure to loop the wire through some ferrite cores, to help with frequency spikes, and that also went through the drag chain – which you’re technically advised not to do but I’m going to risk it coz it looks neater. You’re also meant to fix exposed armour near the end of the cable to the back plate with a strap, which can help with draining EMI.

I’m now testing the spindle, using the toggle switch to manually controller the spindle RPM with a potentiometer. In retrospect I should have placed the LED lights onto a delay-timer relay module as you can see that while the spindle is powering down the lights have already reverted from red to white. Something to remember for the next machine.

Ok so the one nice thing about these enclosures is that I have these attachments that I can fit onto the back, something like that. And this is what I’ve ended up with. I’ve screwed it onto the wall although in doing so I re-realised this corner over here is really damp but thankfully these are IP rated so this should be ok where it is for now. I can open these up to show you what they look like in the inside. So the controller here and the VFD over there. And at some point I’m going to think about ventilation for this enclosure but I’ll do that in the future. I think passive ventilation will be ok in here. Notice that I can turn the spindle on and it can be on for a little while before the fan turns on, and this has a function that you can go to on the display panel to let you know the temperature of the VFD itself. Last time I checked it was only 20 degrees Celsius. This room is actually quite a cool room so it’s nice having up here as it means I have a bit of space below it either for my laptop, so I can work a bit closer to the machine and see what I’m doing. Or just use this general working area.

I still need to make a dust shoe coz the old dust shoe from the previous machine that I’ve dismantled doesn’t actually fit on this and I could probably change the bottom plate to make it work but I think I’d rather redesign it from scratch and solve some of the problems with the older one.

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