# Stepper Motor Cable



## papermaker (May 23, 2013)

I'm curious as to what type of cable/wire everyone is using in the X2 CNC conversions to run from the stepper motors to the drivers. I'm using the Monster kit from Probotix in my conversion. The motors have 8 leads but there are two pairs that are wired together so I will need 6 conductors. They recommend 18-22 ga. wire but everything I've found so far in that wire gauge is solid and not stranded. Does that make any difference? I've read somewhere that the solid is a better conductor.

Anyway just curious  what everyone else is using. Thanks...


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## Tony Wells (May 23, 2013)

From Wiki:

Solid wire, also called solid-core or single-strand wire, consists of  one piece of metal wire. Stranded wire is composed of smaller gauge  wire bundled or wrapped together to form a larger conductor.
 Stranded wire is more flexible than solid wire of the same total  cross-sectional area. Solid wire is cheaper to manufacture than stranded  wire and is used where there is little need for flexibility in the  wire. Solid wire also provides mechanical ruggedness; and, because it  has relatively less surface area which is exposed to attack by  corrosives, protection against the environment. Stranded wire is used  when higher resistance to metal fatigue is required. Such situations include connections between circuit boards  in multi-printed-circuit-board devices, where the rigidity of solid  wire would produce too much stress as a result of movement during  assembly or servicing; A.C.  line cords for appliances; musical instrument cables; computer mouse  cables; welding electrode cables; control cables connecting moving  machine parts; mining machine cables; trailing machine cables; and  numerous others.
 At high frequencies, current travels near the surface of the wire because of the _skin effect_,  resulting in increased power loss in the wire. Stranded wire might seem  to reduce this effect, since the total surface area of the strands is  greater than the surface area of the equivalent solid wire, but ordinary  stranded wire does not reduce the skin effect because all the strands  are short-circuited together and behave as a single conductor. A  stranded wire will have higher resistance than a solid wire of the same  diameter because the cross-section of the stranded wire is not all  copper; there are unavoidable gaps between the strands (this is the circle packing problem for circles within a circle). A stranded wire with the same cross-section of conductor as a solid wire is said to have the same equivalent gauge and is always a larger diameter.
 However, for many high-frequency applications, _proximity effect_  is more severe than skin effect, and in some limited cases, simple  stranded wire can reduce proximity effect. For better performance at  high frequencies, litz wire, which has the individual strands insulated and twisted in special patterns, may be used.

end quote

My personal choice is normally stranded for anything that moves. I also don't like the risk of nicking a solid during any stripping that needs to be done, especially on small gauge wire. And no, I don't use a hot stripper. How much of that wire do you need? I may have some. I have quite a collection of various cables with multi-conductors that I get from removal of electronics at a local hospital. Not spools upon spools, but sometimes quite a few feet. Also, you can go to a heavier gauge wire with only the physical size as a drawback, along with the loss of some flexibility.


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## CluelessNewB (May 23, 2013)

I don't do CNC but I do know a little bit about wire.  If you need the wire to flex you want stranded not solid.   You could double up some 18-3 rubber cord if you can't find anything more appropriate.  The big electronics houses (Mouser, Digikey etc) probably have what you want but in big expensive rolls.   

There is always eBay!  (I know nothing about this seller just what I found with a quick search, you may find better deals)

http://www.ebay.com/itm/CNC-Stepper-Motor-Hook-UP-WIRE-18-6-non-shield-Buy10-increments-/330881673239?pt=LH_DefaultDomain_0&hash=item4d0a15a817


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## Dr.Fiero (May 23, 2013)

As stated...  you WANT stranded.  Solid core can break from flexing over time. And having a powered up stepper wire break is a baaaaad thing!  Driver will likely go -poof-.
Doesn't matter if it's moving at the time or not. They've always go current going through them, if the power is on.

Belden makes a great assortment of cable. 

If you're REALLY feeling daring, you can use plenum rated (stranded) network cable. But it's really hard to work with since it's usually 22ga.
And really - it IS a touch under sized. Though you can double up pairs since you only need 4.

Shielded is a bonus, but not totally required.
(if you DO use the shield, make sure to only connect it at ONE end!)


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## Tony Wells (May 23, 2013)

The plenum vs riser cable difference is in the insulation and the type of smoke emitted if burned. We are required to use plenum cable at the hospitals because of the smoke hazard. You will find that CAT 5 or 6 jumpers are always stranded because they are expected to flex, but standard reels or boxes of cale are solid, in ether riser or plenum.


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## Dr.Fiero (May 23, 2013)

Tony Wells said:


> The plenum vs riser cable difference is in the insulation and the type of smoke emitted if burned. We are required to use plenum cable at the hospitals because of the smoke hazard. You will find that CAT 5 or 6 jumpers are always stranded because they are expected to flex, but standard reels or boxes of cale are solid, in ether riser or plenum.



I just find the jacketing on the plenum rated to be a bit tougher (presumably for going around corners etc and not abrading).
As for the spools...  they come either way (solid or stranded). For example:  http://www.amazon.com/1000ft-Gray-Cat5-Spool-Stranded/dp/B000067ORF/ref=pd_sxp_f_pt

I've STILL got about 6000ft of the stuff from an auction I nailed years ago.
Everyone there thought they were bidding on A SPOOL.  I knew it was the whole damn pallet!  They were laughing at me when I bid over what a single was worth retail.  I had to keep a poker face, then got to laugh at all THEM when the auctioneer moved on to the next lot number!   Ha ha ha!!!  SUCKERS!


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## papermaker (May 23, 2013)

So would CAT5 or CAT6 wire work?! I need about 20' +/-......


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## DMS (May 23, 2013)

I would recommend against using network cable for that much current, it's just too thin. I looked online, and all the 6 conductor 18ga stuff is ridiculously expensive. Do you have a surplus electronic store near you? If so, you might try there. One alternative is to make your own. Get some spools of stranded wire in different colors. Measure out to length, and then encase them in heatshrink, in split loom wire duct, or similar. Personally, I like the expandable polyester sleeving for making cable harnesses. Here are pictures of mine

https://picasaweb.google.com/lh/photo/Dsqc8i9-gFUidvFNaRs9AdMTjNZETYmyPJy0liipFm0?feat=directlink

These are servos, so they have power lines, and signal lines for the encoders too. Everything is wrapped up nicely, ends heat shrunk, and terminated in nice multi conductor plug connectors. 

If you still want pre-made cable, I can take a look at the local surplus place, just let me know how much you want.

Oh, also, I agree with Tony, stranded is the way to go for things that are going to be moving; solid wire will fatigue and break rather quickly.


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## Dr.Fiero (May 23, 2013)

Since you're running steppers, not servos, you could still use network cable.  As I was saying, just double up the pairs.  Lots of capacity then. Leads coming off the motors is usually only 18-20ga.

Go find some cat3 that nobody wants anymore.  Should be dirt cheap!  It's just less twists per foot. And that's meaningless for what you're doing anyhow.  Could probably score a whole spool for 20-30$ I'm betting.

Of course, the only trick then is finding it in stranded.


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## Tony Wells (May 24, 2013)

Dr.Fiero said:


> I just find the jacketing on the plenum rated to be a bit tougher (presumably for going around corners etc and not abrading).
> As for the spools...  they come either way (solid or stranded). For example:  http://www.amazon.com/1000ft-Gray-Cat5-Spool-Stranded/dp/B000067ORF/ref=pd_sxp_f_pt
> 
> I've STILL got about 6000ft of the stuff from an auction I nailed years ago.
> Everyone there thought they were bidding on A SPOOL.  I knew it was the whole damn pallet!  They were laughing at me when I bid over what a single was worth retail.  I had to keep a poker face, then got to laugh at all THEM when the auctioneer moved on to the next lot number!   Ha ha ha!!!  SUCKERS!



I didn't mean that it just wasn't made that way, just that by a wide margin, more network runs in either plenum or riser are solid. It's simply cheaper. The stranded is a little harder to work with on the RJ 45 connectors, jacks mostly. Plugs will crimp on it OK. Punchdown tools don't seem to like the stranded.


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## Rbeckett (May 24, 2013)

I've been running the stranded multi color flat ribbon cables and IDC connectors.  Nice clean and well organized wiring and very easy to follow when tracing a circuist.  The idc connectors just snap onto the ribbon and displace the insulation enough to make an electrical connection.  I don't use them for above 1 amp or above 24 VDC.  At those currents and voltages I use crimp connectors crimped and soldered onto the end of the wire, usually 14 to16 Ga or even larger. 

Wheelchair Bob


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## papermaker (May 25, 2013)

It really pay to be a packrat and also clean your shop. I had completely forgotten that I had stashed away some 6 conductor,stranded,shielded cable from spare parts off my other mill. Now all I need to do is find some plugs for the ends. Pretty sure I don't have any of those stashed.


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## mskobier (Jun 28, 2013)

If the cable you have doesn't work out, you may want to take a look at 8 conductor rotator cable. This type of cable uses stranded wire, and it already has two of the conductors of a larger size. So there is 6 wires that are say 18 ga and the other 2 will be 16 ga. You can also get it in smaller wire sizes and I think up to 14 ga for the two large conductors. New it runs a little less than $1.00 per foot. It is also outdoor rated and the jacket is pretty tough. There is some available on my favorite auction site now. This stuff is often available used. If you know any amateur radio operators (hams), they should be able to help you locate some locally. 

Mitch


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