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  1. #1
    Join Date
    Sep 2010
    Posts
    183

    Shielded cable or not?

    I have a router that I have been running for a year or so now. I'm running steppers with shielded cables, grounded to my control box. I have been running a Porter Cable router. I bought a Chinese 2.2kw spindle and inverter a while back and I'm just getting around to installing it. The P/C router has been running on a Home Depot extension cord. The extension cord is routed with the rest of the stepper cabling. I haven't had any issues (that I'm aware of) with noise or other issues. A decent shielded cable would run about $150.....
    So have I been lucky with my existing extension cord? Do I need a shielded power cable for the spindle? Any insight would be helpful. Thanks in advance..

  2. #2
    Join Date
    Dec 2007
    Posts
    2134
    It would be advisable in my opinion, your going to get a fair amount of noise from the spindle, and depending on how good the noise immunity and earthing of the control circuitry is, it has a fair chance of resulting in unwanted steps or erratic behavour.

    cheers,
    Ian
    It's rumoured that everytime someone buys a TB6560 based board, an engineer cries!

  3. #3
    Join Date
    Apr 2009
    Posts
    266
    $150???

    McMaster.com
    9936K65 16gauge/3conductor Shielded 0.38"dia 18amps 600vac Gray $5.17 for 1-99ft

    and for plugs
    Nema 5-15 125vac 15amps 7216K5@ $6.71 (male) 7216K6@ $11.70 (female)

    is pretty much what i'm thinking of using...
    my first..."Big Ape" CNCRP 2448 Build Log

  4. #4
    Join Date
    Sep 2010
    Posts
    183

    lol $150...

    Quote Originally Posted by kinghong1970 View Post
    $150???

    McMaster.com
    9936K65 16gauge/3conductor Shielded 0.38"dia 18amps 600vac Gray $5.17 for 1-99ft

    and for plugs
    Nema 5-15 125vac 15amps 7216K5@ $6.71 (male) 7216K6@ $11.70 (female)

    is pretty much what i'm thinking of using...
    Thanks for the parts numbers......
    I'm going to use 18/4,flexible, shielded controller cable. If I'm going to use the spendy stuff I'm going to want the extra ground wire......is my guess...
    But no matter how you slice it 30' x $5.17 is still pretty much $150....I guess I should have said I have a 5x10 router and need at least 25' and 30 would be better....


    So I'm going to use shielded cable..one less x-mass present for the kiddies...love this economy...

  5. #5
    Join Date
    Apr 2009
    Posts
    266
    oy, did not realize you had such a big machine...
    my first..."Big Ape" CNCRP 2448 Build Log

  6. #6
    Join Date
    Sep 2010
    Posts
    183

    a little push

    Quote Originally Posted by aarggh View Post
    It would be advisable in my opinion, your going to get a fair amount of noise from the spindle, and depending on how good the noise immunity and earthing of the control circuitry is, it has a fair chance of resulting in unwanted steps or erratic behavour.

    cheers,
    Ian
    Okay-just needed a little push----thanks for your reply. I'm going to use shielded cable.....

  7. #7
    Join Date
    Oct 2008
    Posts
    406
    Try routing the spindle cable by itself, not bundled in close proximity to any control or stepper cables.
    Bob

    "Bad decisions make good stories."

  8. #8
    Join Date
    Dec 2007
    Posts
    2134
    Quote Originally Posted by vpl View Post
    Okay-just needed a little push----thanks for your reply. I'm going to use shielded cable.....
    You won't regret it, the last thing you want to do is try and troubleshoot erratic or intermittent issues. A few wrong steps avoided and the cables probably paid for itself, especially with a machine that size. One other thing that might be of value to you, is a line conditioner, or inductor (RLC type), sitting between the mains feed and the VFD, so any noise coming back via the spindle back into the mains will be cancelled or at least greatly reduced. Simple ones can go for $5-$15. I'm not sure what the guys from the industrial side of the CNC world think of them, but I've always been taught they can be of great benefit. The spindle you'll find is a very, very noisy device electrically.

    cheers,
    Ian
    It's rumoured that everytime someone buys a TB6560 based board, an engineer cries!

  9. #9
    Join Date
    Nov 2011
    Posts
    14
    I met the same problem a few months ago and had to investigate it in depth with an oscilloscope. I agree with the previous post, this kind of VFD is quite noisy. I saw a lot of pulses up to 40 volts (!) in a megahertz range. What's interesting, the less rpm, the larger the noise - so I try to run it at maximum speed whenever possible.
    Generally the noise comes via power wires, not by air. The remedy would be a combination of measures:
    - use a decent AC power filter and do not plug the inverter power cord in the protected circuit.
    - use an optical decouplers between the computer and stepper drivers.
    - use a proper grounding of everything.
    A simple test: I start the spindle, keep steppers active but not moving and watch the leadscrews. If things go wrong, the screws may make small chaotic movements back and forth. Try to lower the spindle rpm - if it gets worse, this is definitely an issue with VFD noise.

  10. #10
    Join Date
    Sep 2010
    Posts
    183

    Thank you!

    Quote Originally Posted by brownfox View Post
    I met the same problem a few months ago and had to investigate it in depth with an oscilloscope. I agree with the previous post, this kind of VFD is quite noisy. I saw a lot of pulses up to 40 volts (!) in a megahertz range. What's interesting, the less rpm, the larger the noise - so I try to run it at maximum speed whenever possible.
    Generally the noise comes via power wires, not by air. The remedy would be a combination of measures:
    - use a decent AC power filter and do not plug the inverter power cord in the protected circuit.
    - use an optical decouplers between the computer and stepper drivers.
    - use a proper grounding of everything.
    A simple test: I start the spindle, keep steppers active but not moving and watch the leadscrews. If things go wrong, the screws may make small chaotic movements back and forth. Try to lower the spindle rpm - if it gets worse, this is definitely an issue with VFD noise.
    Very helpful!!!!!
    I sorta had a "feeling" there may be issues in this department. But I was guessing. This is the exact reason I come to this forum. You checked your system with an oscilloscope (i live like 10 miles from Intel....lol)! No guessing there! Your insight along with the others posted here is so helpful. I will do as you guys suggest with the filters, shielded cable, and grounding. It will be a week or two but I'll get it done. I believe I have the optical couplers built in. I have MDrive Plus steppers with built in controllers.......I'll call IMS to be sure.

    Its super cool to know it makes more noise at low rpm-counter intuitive for a guy with little electrical experience. I didn't even know about a/c filters until this post. I think my router would still be sitting in a box if it weren't for the helpful people on this forum.

    None of your time is wasted on these replies. They are so HELPFUL and put into use!

    Thanks Again,
    Vince

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