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Offline comet

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cat 5
« on: December 20, 2008, 12:26:38 PM »
Hi,
  would cat5 network cable be ok for the wiring to the encoders on a servo system?
     Tony

Offline Hood

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Re: cat 5
« Reply #1 on: December 20, 2008, 01:58:34 PM »
The best is twisted pair shielded cable of which some network cables are. One thing however is to make sure any cable you use has multi stranded cores as if single solid core it will eventually fatigue and snap.
Hood
Re: cat 5
« Reply #2 on: December 20, 2008, 04:51:07 PM »
Hi,

Yes, CAT-5 is fine and a good choice. Make sure you use the stranded cable and not the solid cable as Hood recommended.

Cheers,

Peter.

----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com

Offline N4NV

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Re: cat 5
« Reply #3 on: December 21, 2008, 01:38:52 PM »
I have used solid Cat 5 cable for a couple of years with no problems.  Make sure you run your channel A and B in different pairs of the cable.

Vince
Re: cat 5
« Reply #4 on: December 21, 2008, 03:04:59 PM »
I have used solid Cat 5 cable for a couple of years with no problems.  Make sure you run your channel A and B in different pairs of the cable.

Vince
I have used solid Cat 5 cable for a couple of years with no problems.  Make sure you run your channel A and B in different pairs of the cable.

Vince

Solid core wire is not a good choice for an application where it will be repeatedly flexed.  It will eventually fatigue and fail, and when it does your servo will run away on you, possibly damaging the machine, or hurting someone.  You'll get away with it for a while, but it's a poor choice for long-term reliability.

Regards,
Ray L.
Regards,
Ray L.

Offline comet

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Re: cat 5
« Reply #5 on: December 21, 2008, 04:54:57 PM »
Vince,
   should the other twist be earth/zero volts? I've used two core twisted shielded data cable
a&b together and never had a problem.
   Tony

Offline N4NV

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Re: cat 5
« Reply #6 on: December 21, 2008, 05:19:36 PM »
Vince,
   should the other twist be earth/zero volts? I've used two core twisted shielded data cable
a&b together and never had a problem.
   Tony

It doesn't have to be.  On my first CNC conversion (I've done 5 now), I installed the 0V  and +5V down one pair and had the A and B channels down another pair.  I was not able to tune my Gecko 320s.  It was Marris who figured out the problem.  I just moved each of the A and B channels down their own pair of twisted wires (the other wire in each pair was not connected to anything).  I never had another problem.  BTW, I have found that 95% of tuning problems with Gecko 320s are caused by encoder noise.  Get rid of the noise and you can tune a Gecko by ear in about 5 minutes.

As a test, I used a piece of Cat 5 cable 40' long between the encoder and the Gecko 320 and it worked the same as a 5' length of cable.  I'm using US Digital encoders and their web site says the E2 encoders are only good for 6' of cable. 

As for solid wire, the strand size in Cat 5 is pretty small, around 24 gauge I believe.  It will flex quite a bit.  Make sure you have the cable rigidly supported at the terminations so it doesn't flex at that point.   Never ring or nick the conductor when stripping the insulation or you will cause a stress riser and it will break at that point.  Make sure you have plenty of cable at flex points so the cable bends over a long area, say about 5".  If you bend any wire, stranded or not less then 5 cable diameters it will break in short order.

Vince

Vince
« Last Edit: December 21, 2008, 05:23:34 PM by N4NV »

Offline bowber

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Re: cat 5
« Reply #7 on: December 21, 2008, 05:29:53 PM »
I try to use the stranded Cat5 for network cables but sometimes have toget the solid stuff.
I was having a problem getting full speed on a 100mbps network and found that the pairs were connected randomly, this meant the signal noise was interfiaring with the signal.
Also it's been found that very high frequencies travel on the outer area of the wire so small niks and cracks stop the signal.
Not entirly relavent to CNC but just thought it may help some one in the future.

Steve (on the second bottle of wine)

Offline N4NV

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Re: cat 5
« Reply #8 on: December 21, 2008, 07:19:35 PM »
Maximum frequency for 100% skin depth for #24 solid copper is 68Khz.  A 1200 line encoder turning at 3,000 rpm could get close to that. 

Vince

Offline comet

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Re: cat 5
« Reply #9 on: December 22, 2008, 04:21:16 AM »
Vince,
 I too am on my 5th servo conversion!,I have generally used twisted pair shielded data cable for a&B
But I supose its not data,so maybe the best would be individual/single coax like audio link up cable?
plus its cheap and readily available.
    Tony