I got a 800w 65mm water cooled spindle for my shapeoko 4. I had a 80mm one but the shapeoko 4 is not compatible with carbides 80mm mount and the HDZ isn’t compatible with the shapeoko 4 either.
Any who, I’m using my 1.5kw Huanyang VFD to power it and will be limiting the power going to the spindle. The 4th pin on the spindle was not connected so I have a nice ground connection to the spindle chassis from a copper wire crimp sandwiched between the rubber gasket and the body of the spindle.
On top of this I’m running 16 gauge copper wire to the spindle and each one has its own stainless steel wire sheathing for shielding.
I have 3 questions now.
Do I ground the spindle to the vfd or the machine?
Does the wire sheathing for the spindle need to be grounded at both ends? If so where do I connect those grounds to? The machine or the spindle?
I’m also have two circuits running everything. Spindle, machine, shop vac, air filter, lights etc…. If the spindle is grounded to the machine via the spindle mount, should the machine and vfd operate off the same circuit.
Really I just need some general guidance on grounding everything. Any advice?
Look up “star grounding” for a general idea of what to ground to which and how. Basically, everything should be grounded back to a single point at your wall (or in the case of two circuits, at your electrical panel), and you should avoid creating any loops in your ground path. A loop acts as a big inductor, introducing electromagnetic interference into your less-than-ideal ground.
To answer your questions specifically,
(1) Your spindle should be grounded to both. I’d probably ground the spindle to the VFD, then the VFD [is already grounded] to the wall. The machine will be grounded to the wall on a separate branch of the star ground.
(2) If the sheathing is carrying ground to the spindle, it needs to be connected at both ends. If the spindle is grounded elsewhere, then only connect one end of the sheathing (the end closer to the wall).
Avoiding ground loops can be tricky while you’re getting your head wrapped around the idea, but it’s straightforward once it clicks. The important thing is that each component has one and only one path to ground.
In general, (a) ground as many things to the wall as possible, through a ground prong in their power cable, (b) don’t connect anything that’s already grounded to anything else that’s already grounded, and (c) ground anything that you can ground.
I’m no electrician by any stretch of the imagination.
Can you please define “WALL” in your grounding scenario please?
In my mind I picture drywall and wood studs as being a wall.
I believe Travis is talking about the electrical outlet mounted on the wall.
It’s worth mentioning that not all outlets have a proper safety earth ground connection. Two pin outlets in the US for example may only have two power pins, you need a proper 3 pin with safety earth outlet.
Not sure about the Shapeoko Pro, the old Shapeoko 3 grounds the aluminium rail via the control board, but the rest of the machine is not necessarily grounded (see the post / video on grounding).
As for the VFD, you should have the VFD grounded to the outlet it is powered from, that ground should then go via the VFD to the spindle casing so that the whole VFD & spindle system is safely grounded. The golden rule is that the ground should be able to carry at least as much, preferably more current than the power circuit and it should not be possible to disconnect the ground without also disconnecting the power. The ground of the Shapeoko may well not meet the capacity requirement and can easily be unplugged. RCD / GFCI breakers can’t help you downstream of the VFD as they may not detect the fault and the VFD stores energy anyway. You’ll probably have both the incoming power cord ground and the spindle ground wire both on the ground terminal of the VFD.
I think that it is best to use the fourth core in the spindle power cord to get the ground to the spindle casing, you’ve described connecting that, ideally there would be a screw down connection rather than a pinched wire but… As Travis explains, you should also ground at least the VFD end of the braid and screen of the spindle cable.
Once it’s connected, use a meter to test the ground to the spindle shell.
@ehendrix: @LiamN guessed correctly at my meaning. “Wall” means the ground pin on a NEMA 5 receptacle in the US, or the equivalent pin on your local variety of household power receptacle. In the absence of that, anything connected to earth ground. That could be a copper water pipe, steel methane pipe, steel stud, beam, or girder… it entirely depends on the building and what’s at hand.
I see this discussion getting into both EMI mitigation and safety. @PerchPerkins35, what was the intent of your original question?
I have EMI grounding wire connecting all my rails and C3D router body, but my 24-gauge wire is not sufficient to carry the full current of the router, should their be an electrical fault that would electrify the housing of the router. Right, wrong, or otherwise, I assume that the manufacturer sold me a safe product. We could have a lovely conversation about that assumption, but I don’t go around my house externally earth-grounding all of my lamps for safety.
For the Shapeoko Pro it sounds like ground is dealt in the same way. There’s a really small gauge ground wire attached to the back right Y rail going into the controller enclosure (edit: this is stock out of the box). That said their is also a dedicated drag chain going to the opposite side of the controller (ie. to the left Y rail) for the router/spindle power cable so any spindle grounding would go along that dedicated path to the VFD.
I’d concur with that, the C3D router has to meet US and EU safety standards and is likely double insulated and without a VFD can be usefully protected by a GFCI / RCD breaker. The VFD powered spindles on the other hand frequently fall obviously and badly short of the safety spec we would expect in the West.
This is the spindle with the grounding lug. I sanded back the protective coating on the spindle where the copper touches the spindle body to ensure a good connection. I checked for signal continuity with my multimeter and the entire spindle is grounded through that lug now.
Since the spindle is touching the machine, isn’t the spindle and vfd now grounded through the machine now?
I’ll start by quantifying my response with I’m not an electrician but I’m thinking that the shapeoko 3, 4 and Pro all have that green grounding wire bonded to 1 of the Y rails into the controller ground and out via the power brick (Well that’s how it is on my Pro). Just by looking at the gauge of that green ground wire (Y-rail to controller) is not adequate for the current going through the power cable of the spindles or routers which is why these cables conductive wires are greater in diameter. I have the feeling the ground wire between the Y-rail (machine) and controller is more about allowing any static buildup a path to trickle out to try and avoid some EMI/disconnect issues but I’d leave that up to more experienced members with a better electrical background or someone from Carbide to confirm this.
Ah, a bolted down copper crimp is a lot better than what I was thinking. It might be an idea to use a spiky lock washer to ensure you’re getting contact.
You can also open it up and ground inside from the back of the connector
Yes, there’s a ground path through both the spindle and the machine grounding, that’s where making sure both grounds come back together soon at a ‘star earth’ point such as the three pin outlet comes in to minimise ground loop problems.
However, as Travis pointed out there’s two issues here
Electrical safety, fat ground wire on the spindle that can’t be disconnected whilst the spindle is connected to power
Interference suppression through appropriate grounding of bits of the machine
Number 1 is really not optional so 2 has to work around that.
So I kinda got the idea here. My main question is, won’t the CNC frame and spindle make a ground loop? The CNC is grounded via the little green wire and the spindle would be grounded to the vfd. Won’t this create a problem?
Also for my wire shielding, should I ground it to the chassis?
I have a 3, not a Pro or 4, so I don’t have the same grounding configuration out of the box that you and @Caffein8ted have. I had to do it all myself. That said, take your multimeter and ohm it out — only way to know for sure.
In my case, my Y1 rail was electrically connected to the controller via the controller’s enclosure, but neither were earth grounded. It sounds like this has been addressed in more recent models. I took a piece of copper rod the right diameter for the ground prong in a receptacle, soldered my wire to it, and shoved it in an open receptacle (my shop lights used the hot/neutral prongs but not the ground). My X rail was not electrically connected to Y1, so neither was anything else.
The “protective coating” you referred to is probably anodized aluminum, technically aluminum oxide — a great insulator. If it’s on steel, it’s probably a powder coat finish — also insulating. Generally screw holes are drilled and tapped after finishing (but not always), so screws will make contact with the bulk conductive metal. This doesn’t help if your rails are electrically isolated through Delrin v-wheels, though.
I solved this (I only was worried about EMI) by taking a piece of magnet wire and snaking it through the drag chain. I wrapped it around a screw on each rail and my router mount, which is connected to my router body. You could do something similar, but use a 12 or 14-gauge wire rated for 20 amps given that you have safety concerns as well with your sketchtastic non-UL/CE spindle. Make sure to use stranded wire, because solid wire will break after repeated cycling.
