[990x]

Let me first appologize if this has been asked/answered someplace else. My goal is to install 4 home and 4 limit switches but firstly I would like to clear something up regarding the mesh shielding in my wire. I want to know where the shield terminates. Just on the driver side? Ground on powersupply? It should also be noted that while the wire is shielded it does not have a drain wire, though soldering a wire to the shielding should not prove too difficult.

[Mariss Freimanis]

You'll like this answer. No shielding is necessary. The G540 low-pass filters and optoisolates all inputs. No noise can pass through.

Mariss

[btsioles]

I had a question about this. I have the g540 and my limits are tripping randomly while running. I never had this issue before. I recently switched to the porter cable 690 from a lesser powerful router. The comment from Mariss says that I don't have to worry about noise in my limit cabling, but why am I all of sudden having my limits trip? The only thing that has changed is the router. I know it's not recommended, but I've always run the power cable from the router in my cable chain along with a motor and limit cable. As I said, my machine has been working great up until switching to the more powerful router.

I connected the limit cable foil shielding on one end to the a/c input ground screw on the machine's power supply. This made no difference. I've verified that the shielding does connect to ground using a volt meter.

When I check the voltage of my switches with my machine on, they're around 12.3 volts. I admit I really don't know how to effectively check if I'm getting noise from the router into the limit cable.

I set the debounce in Mach to 150 and that seemed help, but I'd prefer to resolve the issue without using debounce.

Oh, my switches are wired NC, in series.

Any thoughts?

Thanks,
Bobby

[cambosoup99]

g540 maybe shielded.. but your limits switches most likely are not.

correct me if im wrong, but I thought setting a higher denounce level rejects more noise, not a lower level. my debounce in mach is still at defaults 2000,

[btsioles]

g540 maybe shielded.. but your limits switches most likely are not.

correct me if im wrong, but I thought setting a higher denounce level rejects more noise, not a lower level. my debounce in mach is still at defaults 2000,

I had been running with a debounce of zero. So I did raise it. I believe I used the limit wire shielding correctly. Do you have any tips on how to check if it's noise from the router? It only trips under high cutting load.

[btsioles]

The specific bearings inside the blocks are

Huh??

[btsioles]

I've been reading as much as I can about this noise issue, and grounding. What's scary is that there are many different and apparently conflicting suggestions all over the web. I got into info talking about grounding rods. Then I found this article which was somewhat alarming in the sense that people who "should" know what they're talking about are providing very different and conflicting info. Here is that link:

Pitfalls of Powering CNC Equipment | content content from Electrical Construction & Maintenance (EC&M) Magazine

From all of the reading I've been doing, one general statement is that "everything" should be grounded to a single "star ground" point. I'm having a hard time determining where that should be.

I have my power supply and g540 mounted to a wood board, spanned across the stand of the machine. I have my limit/home shielding connected on one end to the power supply's a/c input ground screw. Since my g540 and power supply aren't screwed in a metal case, does the ground input on the PSU serve as an acceptable "earth ground / star ground" for the shielding?

I don't have the machine's frame grounded. I do though have a wire running from the aluminum leg of the machine to pin 4 of the g540, and then a touch plate wired to the V- of the PSU. The touch plate works fine. Everything had been working fine until I switched routers.

I figured I'd provide some more info to see if anyone has suggestions on what might help resolve the tripping issue, and/or any feedback on how I currently have it wired.

I apologize if my questions are dumb, but i'm definitely not an electronics person, and even after lots of reading online, I'm still not sure what to do about this.

[Al_The_Man]

I've been reading as much as I can about this noise issue, and grounding. What's scary is that there are many different and apparently conflicting suggestions all over the web. I got into info talking about grounding rods. Then I found this article which was somewhat alarming in the sense that people who "should" know what they're talking about are providing very different and conflicting info. Here is that link:

From all of the reading I've been doing, one general statement is that "everything" should be grounded to a single "star ground" point. I'm having a hard time determining where that should be.
.

Good Article!

Basically what I have been pushing for some time.
You will still get conflicting sources on thing like ground rods etc, due a lot to the varied types of equipment out there.
The basic concept of Ground plane is that the Earth is considered one conducting homogenous mass and we try to make everything at the same one potential.
The difference between hobby DIY equipment and commercial equipment is often that the DIY system is not only put together with various sources of equipment but may also be powered separately, i.e. P.C., main cabinet, router motor etc.
Whereas the commercial equipment can be designed as one known system and all control contained in one enclosure, where all bonding and grounding are centralized and a common ground star point conveniently set up.
Bonding all machine metallic sections and/or motor frames is important.
With routers, make sure the motor frame ground comes back to the star point.
http://www.automation.siemens.com/do.../emv_r.pdf?p=1
Al.

[btsioles]

With routers, make sure the motor frame ground comes back to the star point.

Al.

Al - I greatly appreciate your response. Do you have any suggestions for me as to where that star point should be in my setup? Simply, I have all my electronics and computer plugged in to a single surge protector plugged into the wall. My gecko and power supply are mounted to a wood board.

From my limited understanding of all of this stuff, my limit switch wire shielding, machine metal surfaces, and the motor frame per your post, should be connected to a star point. Where would you put this star point? Should I use the power supply's ground (green cable from a/c) screw terminal for the star point?

Or do I need to mount my gecko and power supply to a sheet of metal instead of wood, and then run a wire from that sheet metal to my a/c wall plug metal plate / conduit, after all doesn't the wall box go all the way back to ground at my service panel? And actually, my service panel is right next to my cnc machine. Should my star point be a point on the metal of my service panel?

As you can see, I really have no clue, and it seems like a lot of DIY people like myself are unsure as well.

Also your motor frame comment... What does that mean? The body of the router is metal and held to the machine with an aluminum mount. After all, I think this is why my touchplate works without having to connect an alligator clip to the cutting bit.

Sorry for the rambling... This is just a bit frustrating when everything had been working great for months, and I change routers and I get trips. Especially when everything is connected as it was before.

Thanks again!!
Bobby

[btsioles]

Also your motor frame comment... What does that mean? The body of the router is metal and held to the machine with an aluminum mount. After all, I think this is why my touchplate works without having to connect an alligator clip to the cutting bit.

Another question related to my touchplate... I read you shouldn't use "ground" to pass signals. If my router is supposed to be going to star ground, would using the machine's frame as I'm currently doing to pass signal to input 4 of the gecko for my touch plate be in direct conflict of that statement, and cause something to fry? It works fine, and perhaps since it's a momentary controlled action, it doesn't matter, but just wondering if I connected the machine frame to star ground, if that would break stuff.

[neilw20]

I had 'tripping problems' big time yesterday. Was freezing the PC.
Machine had never done it before.
I had serviced the fan in the PC (flat desk version IBM) box in a big steel box with a touch screen.
The top cover was still off. Thought I had disturbed a plug.
Put the cover back on and all is back to normal.

I have no shielding on any machine wiring. All 4 axis worth running on 48v and 12v on logic.
Only the parallel cable and USB to pendant has shielding.

[Al_The_Man]

Al - I greatly appreciate your response. Do you have any suggestions for me as to where that star point should be in my setup? Simply, I have all my electronics and computer plugged in to a single surge protector plugged into the wall. My gecko and power supply are mounted to a wood board.

Well if you have read the article in the link and the one I posted, you will see that the IDEAL is everything in one enclosure where all grounding and bonding is done automatically to some extent by virtue of a common backplane.
So when you go out of this ideal, you have to get creative, if you are mounting everything, or most, on a no-metallic surface then you should have a bonding conductor that goes from each piece of equipment to a central metallic ground termination plate set up at a suitable point.
What I usually use in my cabinets is a piece of aluminum or copper with a number of holes tapped #10 to attach all the bonding conductors etc with ring terminals.

Another question related to my touchplate... I read you shouldn't use "ground" to pass signals. If my router is supposed to be going to star ground, would using the machine's frame as I'm currently doing to pass signal to input 4 of the gecko for my touch plate be in direct conflict of that statement, and cause something to fry? It works fine, and perhaps since it's a momentary controlled action, it doesn't matter, but just wondering if I connected the machine frame to star ground, if that would break stuff.

That should not make any significant difference, in my case I ground all supply commons anyway so it does not matter.
Not sure if your input is direct to the P.P., but if so the P.P. common is at ground potential anyway.
Al.

[btsioles]

you should have a bonding conductor that goes from each piece of equipment to a central metallic ground termination plate set up at a suitable point.
Al.

Great, thanks again for responding. One last question of clarification, where might that central metallic ground suitable point be? I have metal conduit going from my service panel to my metal a/c plug box that the surge protector is plugged in to. Is that a/c plug box suitable? Otherwise, I don't have anything else that is metal around that isn't part of the machine itself.

Let's say I had a metal box with all my equipment in it. Where does that metal box connect to a suitable ground point? Is it enough that the power supply would be in contact with the metal box, and the powersupply is connected to the green ground wire in the plug going into the surge protector?

I'm trying to understand once you have a star point, (which sounds like it should be a piece of metal in contact with the metal case housing your electronics), where does that metal box then connect to an earth ground, or ground or whatever?

Again, I greatly appreciate everyone taking the time to answer my questions.

[Al_The_Man]

Basically a ground star point is a central point, metalic in nature that bonds all metalic parts of the machine as well as any shields and power commons etc.
Connected to this is your Earth ground conductor that is supplied from the service panel, you have one of these in all outlets on a power circuit.
Al.

[btsioles]

Thanks. It's interesting that the document you linked says that shielding should be connected at both ends. Thoughts on that? Should I connect all ends of my shielding to my new star ground point?

[Al_The_Man]

For some time it was recommended that shields be only connected at one end, there has been a new consensus that when equi-potential bonding is carried out, that grounding both ends should be done.
You should connect one end to the star point, in any event.
Also http://www.theencodercompany.co.uk/p...er_outputs.pdf
Al.