[wmgeorge]

Thank you, Gerry. My steppers are 7 amp NEMA 34s. I found some charts online. Looks like they agree with Gecko's founder; 20 awg would do it. That gets closer to a workable fit in XLR connectors.

Mine are also NEMA 34 and with the 18 gauge conductors. The important thing to remember its only drawing the 7 amp at max load.

[GME]

Ok from what I can tell its 18 gauge, 300 volt, 80 DegC cable and in one of the shots you can read the product number. You can download and enlarge as needed.

Thank you for the photos, Bill. I tried to run down all the numbers and codes and came up empty as far as who makes the cable. I get the impression the cable is what's commonly used for USB and similar computer stuff. Hard to find the cable though. Mostly, searches turn up already made up cables and more than 4 conductors.

I'm thinking the XLR connector may fit/clamp okay, if I remove the outer cover and allow the connector to clamp to the braided part, or in the case of Igus CF6, on the plastic sleeve under the braid. Depending where I strip the outer cover, I can get the outer cover into the connector boot, so no inner parts are exposed. Even with 20 awg wire, some of the jackets are too large to fit in the XLR boot.

I suppose the whole exercise suggests I should be using different connectors. I went with XLR, because CNCRP used them and they are fairly compact. Now, it's harder to change, since I already have XLR panel mounts on my control box.

Gary

- - - Updated - - -

Mine are also NEMA 34 and with the 18 gauge conductors. The important thing to remember its only drawing the 7 amp at max load.

Agreed!

[Ntl]

Thank you for the photos, Bill. I tried to run down all the numbers and codes and came up empty as far as who makes the cable. I get the impression the cable is what's commonly used for USB and similar computer stuff. Hard to find the cable though. Mostly, searches turn up already made up cables and more than 4 conductors.

I'm thinking the XLR connector may fit/clamp okay, if I remove the outer cover and allow the connector to clamp to the braided part, or in the case of Igus CF6, on the plastic sleeve under the braid. Depending where I strip the outer cover, I can get the outer cover into the connector boot, so no inner parts are exposed. Even with 20 awg wire, some of the jackets are too large to fit in the XLR boot.

I suppose the whole exercise suggests I should be using different connectors. I went with XLR, because CNCRP used them and they are fairly compact. Now, it's harder to change, since I already have XLR panel mounts on my control box.

Gary

- - - Updated - - -



Agreed!

Looks good Gary! Just to throw a option out there I used DB9 connectors that have a small bob with screw terminals with some 18g shielded cable all from Amazon. The cable is alarm cable and was pretty inexpensive, automation direct sells some better stuff as well as other places. I just went with Amazon because it was the cheapest I could find and I got it in 2 days. So far everything is working perfect as far as all my electronics go, I only have probly 40 hours on the machine so time will tell how good of a job I did. BTW the DB9 connectors I got are supposed to be rated for 10amps it took a while to find them, it's kind of a moot point since my nema 34 637oz motors are 4amp. Let me know if you want a link or pictures for anything I used,

[GME]

Looks good Gary! Just to throw a option out there I used DB9 connectors that have a small bob with screw terminals with some 18g shielded cable all from Amazon. The cable is alarm cable and was pretty inexpensive, automation direct sells some better stuff as well as other places. I just went with Amazon because it was the cheapest I could find and I got it in 2 days. So far everything is working perfect as far as all my electronics go, I only have probly 40 hours on the machine so time will tell how good of a job I did. BTW the DB9 connectors I got are supposed to be rated for 10amps it took a while to find them, it's kind of a moot point since my nema 34 637oz motors are 4amp. Let me know if you want a link or pictures for anything I used,

Thanks, Dan. DB9s in 10 amp would have been fine but for the fact that my control box already has panel mounted XLRs. I would have to cut a big hole, make a cover plate to hold the DB9s and rewire them. I'd also have to change over my steppers. I'd be a lot happier with the XLRs I'm using, if I can get shielded wire that fits. I may rethink the shielding, although I'd still prefer to use it. It does no harm, and I'd rather overbuild a bit.

Thanks for the offer of information on your connectors. I think I'll pass for now. I'm still working on some ways to make it all work out with XLRs. I found some braided shield wire in 18 awg that's a little smaller on OD than typical, and the price isn't too bad. My main concern with it is flexibility/stiffness. I'll know better about that when it arrives. If it turns out to not be suitable, I'm going back to IGUS and will make it work somehow. I may turn to 20 awg, but I still like to stay on the overbuild side.

I working on modifying the XLRs to make them accommodate larger cable diameters. I may be able to take out the XLR's internal clamp and use heat shrink on the connector boot and wire jacket to provide the needed strain relief. I need to do some experimenting to see if that, or something else might work. To get it all to mate well, I may have to get some 3:1 or 4:1 adhesive heat shrink. Unfortunately, it may make getting the connector apart in the future a chore. I guess it's all about compromises.

Gary

[Ntl]

Oh gotcha, I didn't know you already had all the connectors I'm sure you get it figured out. Looking forward to seeing that machine cutting some parts, I'm sure you are too.

[GME]

After much additional searching, I finally gave up on finding cable with finely stranded conductors and a braided shield that would also fit into an XLR connector. I found some cable that would work, except it had 16/30 stranding. 16/30 is way too stiff for constant flexing. I really would have liked to use Igus CF6, but it doesn't come in 20 awg, which might have fit the plugs.

So, I decided to bite the bullet and purchase Avid CNC's already made up 18 awg cables. Very pricey as compared to making my own - if I could find the cable I wanted. However, the cable is pretty much limp, which is great. The braided shield is grounded, which is good. All of the solder connections are covered with heat shrink. Overall, very professional work. My only complaint (other than price) is with cable lengths. They come in 12', 20' and 28' lengths. I had excess cable for each axis. Not the worst thing in the world, and to be expected. And yes, I do have the option of cutting the cables to length and soldering on new connectors. At this point, I don't plan to do that.

I've connected and run the 4 stepper cables in my cable chains (also from Avid CNC). All that's left is making up my spindle cable. Right now, I waiting for a new grounding clip for inside my VFD box. (Note: My control electronics are in one box and my VFD and 12V for my water cooled spindle pump are in a separate box). I am borderline paranoid about noise interference, so putting the VFD in a separate box made sense to me. I've never had a noise problem, except when I added some PVC pipe to my dust collection system. The static from the dust collector pipe and hose tripped my NPN proximity switches, until I got the hole and pipe properly grounded.

Once I get my spindle hooked up (with shielding grounds at each end), I will be moving on to adding my spoilboard and bed side skirts. Note: in case I haven't mentioned it previously, I opened up my spindle and connected a ground wire to the spindle cap and soldered it to Pin 4 of my connector. I have continuity between pin 4 and the spindle body. Also, I removed the connector that came with the spindle and replaced it with a larger one.

Gary

[pippin88]

Making cables is I think my last favourite part of building a machine.

Very hard to find the best combination of came and connector (that is actually available and doesn't require a huge minimum order).

Then I have to solder the fiddly things!

[GME]

Making cables is I think my last favourite part of building a machine.

Very hard to find the best combination of came and connector (that is actually available and doesn't require a huge minimum order).

Then I have to solder the fiddly things!

Same here on making up cables. Yuck!

I've been messing about with my spindle connector. I changed the supplied connect to to a 20mm style of a different sort, but the cable I've selected is too small for the cable clamp. So, grounding the shield at the spindle end becomes an issue, not to mention strain relief. Right now, I'm trying to figure out a modification to make it work. I've flattened out a copper plumbing fitting. I'm going to clean it, tin it, drill some hole for the fixing screws and see if I can make it work. Not holding my breath, but it worth a try. If it works, I have a very heavy duty connector and a good shield ground.

Note: I've had this connector on the spindle for a long time. On my previous machine, I failed to ground the shield at the spindle (it was grounded in the box housing the VFD), and took up the slack in the connector's cable clamp with thick electrical tape. Fortunately, I didn't have noise issues, which in reflection, was just plain dumb luck. I don't want to have to open the water cooled spindle, if I don't have to, so I'm trying workarounds. Like you observed, finding the right cable/connector combination is tough. I could move up to 10 awg cable, but I don't want to do that for a 2.2kw spindle. I wrap the cable at the VFD end around a ferrite core, and the cable I'm using goes around it 4 times. Were I to go with 10 awg, I couldn't use the ferrite core. I believe the ferrite core kept me from having problems with not grounding my shield at the spindle end. I want to continue using it for whatever noise reduction it might provide.

Gary

[Ntl]

Same here on making up cables. Yuck!

I've been messing about with my spindle connector. I changed the supplied connect to to a 20mm style of a different sort, but the cable I've selected is too small for the cable clamp. So, grounding the shield at the spindle end becomes an issue, not to mention strain relief. Right now, I'm trying to figure out a modification to make it work. I've flattened out a copper plumbing fitting. I'm going to clean it, tin it, drill some hole for the fixing screws and see if I can make it work. Not holding my breath, but it worth a try. If it works, I have a very heavy duty connector and a good shield ground.

Note: I've had this connector on the spindle for a long time. On my previous machine, I failed to ground the shield at the spindle (it was grounded in the box housing the VFD), and took up the slack in the connector's cable clamp with thick electrical tape. Fortunately, I didn't have noise issues, which in reflection, was just plain dumb luck. I don't want to have to open the water cooled spindle, if I don't have to, so I'm trying workarounds. Like you observed, finding the right cable/connector combination is tough. I could move up to 10 awg cable, but I don't want to do that for a 2.2kw spindle. I wrap the cable at the VFD end around a ferrite core, and the cable I'm using goes around it 4 times. Were I to go with 10 awg, I couldn't use the ferrite core. I believe the ferrite core kept me from having problems with not grounding my shield at the spindle end. I want to continue using it for whatever noise reduction it might provide.

Gary

There are different views on where the shield should be grounded and a lot of debate on the subject. I have chosen to go with the drain only on the VFD side and haven't had one issue with the noise. I did the same thing for my steppers as well. I've read a lot about the subject and my take is it should only be grounded on one side so that's how I did it with my machine. I would think that if I would ever have had a problem with noise I would have by now. I think a lot of the ground loop argument is up to interpretation and it comes down to old vs new wiring practices. I honestly don't think you just got lucky since I'm not a lucky guy and mine works great grounded just on the earth ground. I'm sure you will get responses going both ways and if you feel more comfortable grounding on both sides and it works great, if you have a issue with noise due to introducing a ground loop it's easy to disconnect the shield wire from the spindle.

Dan

[pippin88]

My (limited) understanding was that for VFDs the shield is meant to be connected at both ends.

For most other purposes it's at the controller box end or vigorously debated.

[GME]

There are different views on where the shield should be grounded and a lot of debate on the subject. I have chosen to go with the drain only on the VFD side and haven't had one issue with the noise. I did the same thing for my steppers as well. I've read a lot about the subject and my take is it should only be grounded on one side so that's how I did it with my machine. I would think that if I would ever have had a problem with noise I would have by now. I think a lot of the ground loop argument is up to interpretation and it comes down to old vs new wiring practices. I honestly don't think you just got lucky since I'm not a lucky guy and mine works great grounded just on the earth ground. I'm sure you will get responses going both ways and if you feel more comfortable grounding on both sides and it works great, if you have a issue with noise due to introducing a ground loop it's easy to disconnect the shield wire from the spindle.

Dan

Thanks, Dan. I'm going with mactec54's advice on the subject (It's all over the Zone). In the off chance it doesn't work, I'll adjust. At this point, I don't see a downside to going the extra mile.

Gary

[Ntl]

Thanks, Dan. I'm going with mactec54's advice on the subject (It's all over the Zone). In the off chance it doesn't work, I'll adjust. At this point, I don't see a downside to going the extra mile.

Gary

I see what you mean, I do wonder when it became the way to go on vfd motor cable to "trap" the noise inside the cable instead of "draining" it out to the earth ground. I've also read that you should install a filter but I didn't do that either and I don't have a noise problem. Heck I didn't even ground my dust collection hose and I haven't blown up amazingly, I know I'm living dangerously lol.

But seriously maybe I am lucky after all since I have had zero issues with noise and my vfd is installed in the same enclosure as all my electronics. I guess it's just beginners luck that my controller and electronics is by far the best part of my machine. It's just a shame that the Saturn had so many issues that I had to deal with.

Post some more pictures of your machine now that it's finished up and some videos, I want to see all your hard work and the finished product. It's looking very nice so far Gary looks like you did a great job!

Edit: Do you think it's possible that since we are running small spindles and VFDs thats why we haven't had any noise problems having not installed the drain on the spindle side? I wish I had a scope so I could see the difference having one side vs both. Do you know of any documentation that someone has done that I could look at showing the difference with a scope? All I've been able to find is written documents but no visual proof of the difference. I have read that it's supposed to prevent shock, but I would think that if there is current running through the shield you would have bigger problems going on. It is interesting that you can go to just about every forum that exists and there will be a conversation about this topic. I do see now after reading more about it yesterday that motor cable should have the drain on the motor and VFD. There's also supposed to be isolated bus bars and filters kind of over my head since I'm not a industrial machine technician. IDK maybe on a small router it's not a big deal but if you had a high HP motor it would be a bigger problem? Either way I'm not going to clog up your build thread with a bunch of irrelevant questions and topics that have been gone over and over again.

Sorry about bringing it up I shouldn't have especially if I'm wrong about the correct way to do it. It appears that the things I read are the old way of doing it. I also wonder if my spindle is grounded since the braid is in contact with the metal plug even though I didn't physically connect the drain wire.

You guys got me thinking about this again. Do you or anyone else know where it's documented other than from Belden on the proper shield termination for VFD driven spindles? I could have sworn I've read that you just do it on the VFD side.

Dan

[GME]

I see what you mean, I do wonder when it became the way to go on vfd motor cable to "trap" the noise inside the cable instead of "draining" it out to the earth ground. I've also read that you should install a filter but I didn't do that either and I don't have a noise problem. Heck I didn't even ground my dust collection hose and I haven't blown up amazingly, I know I'm living dangerously lol.

I think it just one of those things that evolves over time based upon experience. I read something suggesting that the old way had to do with concerns over the possibility of creating ground loops. Apparently, the current way removes those concerns. I'm guessing using a star ground was the ticket.

You're luck with your dust collection hose. When I added some PVC piping to my dust collection system, I couldn't keep my machine running because of the proximity switches tripping from all the static. Grounding solved the issue.

I too have read about adding a filter to the incoming power line. I haven't added one, and don't plan to, unless I get noise problems. They aren't all that expensive, but I'm trying to slow the outflow of bucks.

Post some more pictures of your machine now that it's finished up and some videos, I want to see all your hard work and the finished product. It's looking very nice so far Gary looks like you did a great job!

Thanks, Dan. It's been a journey. I've tried hard to build the best machine I can. Time will tell how well the attention to detail pays off. I hope it's a stiff as it looks like it should be. More to come, including photos. I'm not sure about videos. I've never tried to do them. I'll have to do some experimenting.

Edit: Do you think it's possible that since we are running small spindles and VFDs thats why we haven't had any noise problems having not installed the drain on the spindle side? I wish I had a scope so I could see the difference having one side vs both. Do you know of any documentation that someone has done that I could look at showing the difference with a scope? All I've been able to find is written documents but no visual proof of the difference. I have read that it's supposed to prevent shock, but I would think that if there is current running through the shield you would have bigger problems going on. It is interesting that you can go to just about every forum that exists and there will be a conversation about this topic. I do see now after reading more about it yesterday that motor cable should have the drain on the motor and VFD. There's also supposed to be isolated bus bars and filters kind of over my head since I'm not a industrial machine technician. IDK maybe on a small router it's not a big deal but if you had a high HP motor it would be a bigger problem? Either way I'm not going to clog up your build thread with a bunch of irrelevant questions and topics that have been gone over and over again.

I don't believe that using smaller VFDs and spindles is necessarily the difference between noise/no noise, although I suspect that larger equipment has the potential for putting out more. I'm far from an expert on the subject.

Interestingly, I happened to talk with a fellow the other day who does a variety of installation work utilizing VFDs and motors. He installs elevators, chair lifts and motorized displays in museums and for trade shows. We talked about VFD noise in particular. It's a problem, because many of his displays have video components that can suffer badly from VFD noise. He reinforces that proper grounding is essential, and also mentioned that physical separation helps as well. They always ground the motor cables at both ends.

Sorry, but I haven't seen anything on using a scope. I believe Bill George used a scope to measure for noise. If he's hanging around, maybe he can weigh in on the subject.

On shock hazard, are you possibly confusing connecting a ground to the spindle with grounding the shield? As you've probably read, most Chinese spindles aren't grounded internally, but need to be. When I changed out my cable connector, I added a ground under the cap. There is much here on the Zone about it, and I believe there are some videos on YouTube. Did you open up your spindle and make sure there was an internal ground, or use a multi meter to check for it?

Your use of the word "drain" has me a little confused. When I see the word used, it is usually in connection with a drain wire used to ground foil shielding (although I've also seen it used with braided). I could be mistaken, but I don't believe you are supposed to use just a drain wire for grounding the cable to the spindle at either end. Rather, I think you're suppose to ground the shield itself. That's the way I've done it. I folded the shield back over the outer cover and clamped over that. At the VFD end, I made up a clamp that screwed down to the back plate (after removing the paint). My back plate is connected to the star ground. I used my multi meter to ensure continuity.

Sorry about bringing it up I shouldn't have especially if I'm wrong about the correct way to do it. It appears that the things I read are the old way of doing it. I also wonder if my spindle is grounded since the braid is in contact with the metal plug even though I didn't physically connect the drain wire.

No need to regret bringing up the subject. It a topic that keeps coming up and will almost certainly keep coming up. It's good to have the discussion. I take the time to read posts on the subject whenever I find them.

Your comments suggest that you haven't confirmed that your spindle is grounded. Grounding the shield won't do it. You need to have a ground inside the spindle attached to the ground pin on your connector. I don't recall whether you have an air cooled or water cooled spindle. Air cooled is easier, because you don't have to worry about the seals for the fluid passages inside. Water cooled uses o-rings to seal. When I popped the cap, I found that the o-rings were a mess and not trustworthy when reassembling. So, I had to wait for some new ones to come in the mail, before I could put it back together. One of the advantages of air cooled, but I'm still happy I went with liquid cooling.

A multi meter is a good way to confirm that you have grounds everywhere you need them.

You guys got me thinking about this again. Do you or anyone else know where it's documented other than from Belden on the proper shield termination for VFD driven spindles? I could have sworn I've read that you just do it on the VFD side.

Dan

Yes, I've seen documentation from other than Belden on how to terminate shielding and I've seen conflicting techniques. I've seen some endorsing creating a pigtail from the braid and connecting that (e.g. Belden). mactec54 discourages the pigtail technique. I don't know enough about it to select one way or the other on my own, so I elected to go with a source I trust. mactec54 was/is that source. For documentation, use the following search term on the web: vfd cable grounding method

Gary

[ericks]

Well done, you making good progress

[wmgeorge]

Yes I used a oscilloscope to check my system for noise along with a RF Field strength meter for radiated RF, zero Nada. My spindle is grounded with a ground wire not the pin method, my shields are soldered per accepted practice. Nothing and no issues and I have been running the machine nearly non-stop. Proper machine grounding is very important and mine is.

[Ntl]

Gerry I did soldier in a ground wire to the spindle case. What I was talking about with current getting into the shield was something I read in a electrician forum. Apparently some guys have had a problem with it, I personally don't see how it's possible if everything is grounded properly. But I don't do this for a living so I'm not going to argue with the professionals that work on hundreds or thousands of different machines. The guys who were talking about it didn't say if it was CNC motors and VFDs just that they've seen it before where a shielded cable was conducting current in the shield and when they went to connect the drain wire it sparked.

As for your other question I'm using Automation Direct VFD cable and it has braid, foil, and a copper drain wire. I have the drain wire connected to the earth ground and like I said I have the green ground wire connected to the spindle body and to the earth ground.

What I was talking about as far as maybe my drain is grounded at the spindle is I have a metal connector on the spindle and the VFD cable braid is in contact with the connector. So even though I didn't connect the copper drain wire to the ground pin on the spindle, I think I may have unintentionally grounded the shield to the spindle. I honestly kind of forgot about it until we were talking about connecting the sheild at both ends. Originally I was thinking that the rubber gasket would isolate it, but I didn't think about the metal screws that bolt to the spindle body, also my ground wire is attached to the same surface.

It's kinda funny that once you start writing you sometimes answer your own questions.

Dan

[GME]

Well done, you making good progress

Thank you, Erick. As they say, 'slow and steady wins the race.'

Gary

[GME]

Yes I used a oscilloscope to check my system for noise along with a RF Field strength meter for radiated RF, zero Nada. My spindle is grounded with a ground wire not the pin method, my shields are soldered per accepted practice. Nothing and no issues and I have been running the machine nearly non-stop. Proper machine grounding is very important and mine is.

Just curious, but where on the spindle did you attach the ground?

From all I read, I don't get the impression that soldering the shield is an "accepted practice." I don't know enough to agree or disagree, but I don't see soldering as a common method. For the shield, I mostly see mechanical fastening, whether it's clamping the shield in a grounding device (e.g., metal gland, clip on system), or attaching the shield to a ground post. What did you solder the shields to? I'm having difficulty visualizing how you did it.

It's great that you have no noise. I hope I'm as fortunate.

Gary

[wmgeorge]

Its attached to the metal frame of the motor.

[GME]

Gerry I did soldier in a ground wire to the spindle case. What I was talking about with current getting into the shield was something I read in a electrician forum. Apparently some guys have had a problem with it, I personally don't see how it's possible if everything is grounded properly. But I don't do this for a living so I'm not going to argue with the professionals that work on hundreds or thousands of different machines. The guys who were talking about it didn't say if it was CNC motors and VFDs just that they've seen it before where a shielded cable was conducting current in the shield and when they went to connect the drain wire it sparked.

As for your other question I'm using Automation Direct VFD cable and it has braid, foil, and a copper drain wire. I have the drain wire connected to the earth ground and like I said I have the green ground wire connected to the spindle body and to the earth ground.

What I was talking about as far as maybe my drain is grounded at the spindle is I have a metal connector on the spindle and the VFD cable braid is in contact with the connector. So even though I didn't connect the copper drain wire to the ground pin on the spindle, I think I may have unintentionally grounded the shield to the spindle. I honestly kind of forgot about it until we were talking about connecting the sheild at both ends. Originally I was thinking that the rubber gasket would isolate it, but I didn't think about the metal screws that bolt to the spindle body, also my ground wire is attached to the same surface.

It's kinda funny that once you start writing you sometimes answer your own questions.

Dan

Maybe the current in the shield had to do with induced current. I think I read about that as a possible issue. Like you, this stuff is not my area of expertise. I'm great at following instructions, and have built some fun stuff, like a partially automated electric brewery, but I'm light on theory.

If in doubt about your shielding being grounded in the connector, dig out the multi meter and check for continuity. Just remember that it may be grounded, but not "well grounded." A few strands could come up with continuity, but the overall grounding may not be good. I thought I was with you, until you mentioned the rubber gasket. That would surely isolate the shield and don't quite follow how the screws would figure into it.. I'd have to see how you have your grounding done to have much to say about it. Later, I'll post some pics of what I did at the spindle end. I'm waiting for an Icotek shield clamp (made in Germany) for the VFD end that's on order. It's the clamp that mactec54 often shows in his posts on grounding.

See why it's good to raise the discussion again? Sometimes good to put the subject out there every now and then.

IMO, this is a topic where pictures help a lot. Written descriptions often raise more questions than answers - especially for those of us for whom things electric/electronic were not an occupation - probably most of us hobbyists. What makes matters trickier is that there is often disagreement among those "in the know." I've seen too may spitting matches with everyone dug in and invested in being right at all costs. Scorched earth. For the rest of us mere mortals, it detracts from the discussion and leaves us without an answer we can pursue confidently. Too common on this and other sites. Sad.

Gary