CB CNC Part 13 – Wiring Stepper Drivers To Controller & Panel Mount

Ok in the last video I powered, or wired power to all the different components in the enclosure. This included the stepper drivers, the driver board, the variable frequency drive, powering the power supply units – the 12, the 24, and 36v PSU’s all via the motor contactor unit, which has a nice juicy one button, and off button.

In this video I’m going to start wiring stuff to the control board and I’m going to start with the stepper drivers. There are two wiring diagrams in the M542T stepper driver user manual, depending whether the control board you are using, uses an active high or low signal. All the GRBL controllers I’ve come into contact with use an active high low signalling.

CORRECTION 0:47 Input coming into the controller such as the start, hold and reset buttons, the probe and limits switches all need an active low signal – which means when the pin is receiving a voltage (normally 5v) it is disabled, and if that goes to 0V is it active. The coolant and spindle enable pins use an active high so the off state is normally at 0v and that goes up to 12v to turn those on. In the case of stepper drivers a high and low signal result in moving the stepper in one direction or the other. When I built my first controller I didn’t use a probe or start/hold buttons, and my limits were simple mechanical limits which didn’t require me to investigate how they worked.

Which means the pulse, direction and enabling wires go to the positive terminals on the stepper drivers. All the ground pins are then wired to a common ground.  In my case this will go to these will go to the PSU as there isn’t enough ground ports on the control board.

For this video I am using a new soldering station sent to me by BangGood, we made friends again.

I’ve seen one of these before, and that’s going straight into the bin.

It’s a soldering iron, heat gun, DC voltmeter and DC power supply all in one. What could go wrong? I’m going to test it out for this build, and will provide a link to the item in the description with a few comments. Anyway the first thing I am doing is cutting some screened two core cable to various sizes to go between the controller and stepper drivers.

I expose about 25mm of the two cores cable, on the side which will go to the control board. I stripped about 6-8mm of sheathing to expose wire for the boot ferrules. I also put about an inch of heat shrink to neaten that end a little.

I’m just doing the opposite end now.

On the other side I soldered a length of green and yellow cable to the screening wire, which I also wrapped with heat-shrink.

This wire will go to the power ground terminal on the stepper driver, and screen or shield the direction and pulse coming into the driver boards.

I’ve just wired a bit of cable between the z axis, direction and pulse to the stepper driver. I’ve also connected the wire to the shielding or screening which will eventually go to the ground here. I think that’ll be the easier way of doing it. I still have to connect the enable which from what I’ve seen is simply daisy changed along the different stepper drivers. So this is one and it looks like it works ok. I’m hoping I’m not putting too much strain on the joint but it looks like it soldered pretty well on. I’ll do the next one now and show you how I’m doing it.

If it doesn’t catch when they trying to stop just hold that end down with your fingers – the wire is really tough. These are the ferrules. I’m using the crimping end on the pliers which is this end here.

Let’s go more like 22mm up to 25mm.

I do have about a mm and a half of metal e exposed at the terminals. I think I could have bought some 6mm ones.

I use some off-cuts of wire to daisy chain the enable cable between the four stepper drivers and the control-board. I use double boot ferrules can take two 1mm cables to daisy chain the small pieces of wire together.

I’m now wiring the ground from the negative pulse, direction and enable terminals of the stepper drivers to a common ground on the 36V PSU. The shorter pieces between each driver’s terminals are 5cm long, and 9cm between each driver. I also had to cut down the copper strands a little so three wires could fit into the double boot ferrules.

Ok, probably should have done this first. It looks mental.

You want to make sure that you screw into the flat edge or onto the back of that, not onto the side as you could looses the crimp. These panel holes make it so much easier to work on this inside the box. Ok I’m going to mark up the panel which will have the aviation sockets which will have the aviation sockets for the stepper drivers and limit switches.

Ok this is how I’m going to put the aviation sockets. I have four with five pins, one of the pins will be where the shielding goes from the wiring outside the case, into the case and then to the ground. These three will be the limit switches, again there will be one extra pin grounding the shielding, and this one here will be the probe and again one extra pin.

I’ve just labelled up what these should be.

And I’ve got the four core wire.

Ok this is the solder I’ve been using to attempt to wire the panel connection aviation sockets. This stuff here I bought from Mplins some time ago, and its 1mm lead free solder, and I’m assuming the melting temperature is a lot higher than leaded solder. And I’ve always found it quite difficult to use.

With the soldering station I was sent a bit of solder here. This stuff looks a bit better and thinner 0.8mm, and it also have some information compared to this one. Maybe this is 0.7 flux, I need to check what the CU stands for? 63% SN, 37% PB and I’m assuming the 1.2% is the content of flux, and that split is between leaded and tin. This stuff was from felder, and this was very expensive. This cost me £23. This stuff has 2% silver as well as lead, and it’s also a narrower gauge, 0.5mm. It also have has a lot more flux 3.5%. I find this very difficult to use.  I’m curious to try this one and that one. The other thing I’m going to do is change the tip of this soldering iron to something with a wider edge, maybe this one in the middle here.

So you can see I had my soldering iron set really high when I was using this solder before – I had it up to 350 that that was too much. The melting temperature of this stuff is around 180 celsius, so I’m hoping if I go to 200 which is quite low, maybe 210 so it’s a bit quicker, no fuck it 220 that should be ok.

I’ve cut the other sheathing for the four core wire going between the stepper drivers and aviation socket, back about 30mm and about exposed 6mm of copper wire to solder too.

This is my extraction, its going all the way out of the window.

I really don’t like soldering aviation sockets. I think I shaved off an hour since the last time I did this, but it still took several hours to finish and I have more soldering to do in the future. I soldered the wires with the socket on the table and the cable held from above.

Ok that’s a really horrible job but…

I then checked all the connection with a voltmeter to make sure nothing would short, and also squirted a massive bit of hot glue between all the terminals – for permanent strain relief.

I know you’re not meant to do that, and obviously if there is a good reason why you shouldn’t do that please let me know, but in my current post soldering marathon, I’d put concrete on this if it would keep it in place.

I also covered my horrible soldering work with a nice bit of heat shrink. I wish I’d used the weipu panel mounts with screw terminal but they would have been quite expensive and taken up a lot more space on the enclosure.

Ok I’m just going to put a bit of cable on the end of the screen or shielding here, and that’s going to go on the ground on the stepper drivers.

I used a single cut piece of terminal block to join the screening ground from either side of the stepper driver to a single piece of wire that can fit into the appropriate terminal.

So what I’m doing is I’m touching an individual contact on this side and all five pins on the aviation panel mount and just checking if there are any shorts.

I’ve got the A X Y Z going to panel mounts on this side, and the opposite ends going to the controller. The spindle enable is daisy chained in the red, and the ground of the pulse, direction and enable of all stepper drivers goes to the ground on the 36v power supply unit. I’ve also ground the screening on the pulse and direction single wiring from the controller, and the two phases going to the aviation panel mounts. In the next video I will wire up the panel mounts for the proximity sensors, and their voltage dividers within the enclosure.

Since this video I’ve also finally figured out how to solder aviation panel mounts, so I will make a separate video about the method that worked for me.

Thanks again for watching and don’t forget to sacrifice a thumb to keep the algorithm gods happy.

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