Stepper motor wiring: Shielded or Unshielded?

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Stepper motor wiring: Shielded or Unshielded?

Postby jammer » Tue Oct 08, 2013 9:10 pm

I am at the point where I need to start wiring everything up. When I first ordered everything I sent an email to inventables asking about using their shielded 18ga stepper wire for the Ord Bot. Got antsy the next day and gave them a call. The nice guy on the phone stated that it would work well so I ordered 20 feet of it. The next day I get an email response from them stating that they did not recommend thier shielded wiring for the Ord Bot since the runs were so short and the wire is somewhat stiff. So I ordered some of this from Amazon (http://www.amazon.com/gp/product/B00D97 ... UTF8&psc=1). It is really nice wire.

My question is this. I will be using the X3 controller and have read that there has been issues with noise from the cabling. Should I use the stiff shielded wiring or the extremely flexible 22ga silicone wiring I bought from Amazon.

I did buy the tool and connectors to wire everything up with Molex connectors. I love that stuff!
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Re: Stepper motor wiring: Shielded or Unshielded?

Postby cvoinescu » Wed Oct 09, 2013 12:13 am

Molex make a gigantic, truly humongous range of connectors. Which one are you enthusiastic about? :)

There shouldn't be any serious issues with unshielded cable. If anything, I'd use shielded wire for the limit switch connections. The heaters couldn't care less, and the thermistors have large filter caps so they should be fine. Still, if you're concerned about generating interference, it helps a lot if you twist all four wires for one motor together. Don't braid them, twist them -- easy to do if all four wires are loose at one end, nearly impossible if both ends are connected -- and keep in mind that you lose a little length when twisting them.
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Re: Stepper motor wiring: Shielded or Unshielded?

Postby jammer » Wed Oct 09, 2013 4:19 am

cvoinescu wrote:Molex make a gigantic, truly humongous range of connectors. Which one are you enthusiastic about? :)


I purchased these part numbers from Mouser (discovered the part numbers on the Ord Bot Wiki wiring page- (http://www.buildlog.net/wiki/doku.php?id=ord:wiring):

538-43030-0001 Female crimp pin
538-43031-0001 Male crimp pin (hint - order at least 100 to save 75% on the cost)
538-43025-0400 Male 4 position Molex connecter
538-43020-0401 Female 4 position Molex connecter
538-43645-0200 Male 2 position Molex connecter
538-43640-0201 Female 2 position Molex connecter
571-876663 Female single position MOD pin (for plugging individual wires onto a header on a PCB)

I didn't purchase the plastic connecter for the female single pin. I plan on just covering it up with heat shrink tubing after crimping it. I am planning on using these to connect the limit switch wires to the PCB limit switches that were included in my Ord Bot kit from RRP.


(Don't pay any attention to the pictures on the individual Mouser page for each item as the pictures are generic and do not represent the number of positions accurately.)

I purchased this crimper from Pololu:

http://www.pololu.com/catalog/product/1928

I almost wish I had followed Bart's recommendation on the wiring page and splurged for the actual Molex branded crimp tool off of eBay. The pololu crimpers are a good value. If I find I am doing a lot of small gauge wiring on other electronic kits in the future I will probably sell these and splurge for the Molex crimpers. Don't get me wrong, the one from Pololu does a great job but it is absolutely critical that you place the wire and crimp pin perfectly in the crimper for it to work. It only took me a couple of crimps before I learned exactly how to place the pin in the crimper. I watched this video about how to use these crimpers and it helped me a lot: https://www.youtube.com/watch?v=GkbOJSvhCgU These crimpers do work really well but it just takes a lot of attention to detail to get the crimp right. I am a big believer in buying what you want the first time where tools are concerned and I have read that getting a perfect crimp is much easier with the Molex branded crimp tool.



cvoinescu wrote:There shouldn't be any serious issues with unshielded cable. If anything, I'd use shielded wire for the limit switch connections. The heaters couldn't care less, and the thermistors have large filter caps so they should be fine. Still, if you're concerned about generating interference, it helps a lot if you twist all four wires for one motor together. Don't braid them, twist them -- easy to do if all four wires are loose at one end, nearly impossible if both ends are connected -- and keep in mind that you lose a little length when twisting them.


Thanks for the info on the wiring. I am going to take your advice and use the silicone wiring for the motors & shielded for the limit switches. I will also twist the wires before putting them in the braided wire sleeves.

I will post some pictures tomorrow of my progress. I need to get a build log started.
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Re: Stepper motor wiring: Shielded or Unshielded?

Postby cvoinescu » Wed Oct 09, 2013 12:48 pm

Thank you for clarifying. The Molex Micro-Fit 3.0 range is very nice indeed. Mini-Fit Jr. is also nice (it's the size used for ATX PC power supplies).

Good luck with your build!
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Re: Stepper motor wiring: Shielded or Unshielded?

Postby flickerfly » Wed Oct 09, 2013 7:20 pm

Yeah, the molex stuff is cool. JST has a similar range. You can get samples of connectors from both organizations. Molex is much better equipped for getting samples though. There are some things to like about JST as well.
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Re: Stepper motor wiring: Shielded or Unshielded?

Postby jammer » Thu Oct 10, 2013 4:42 am

flickerfly wrote:Yeah, the molex stuff is cool. JST has a similar range. You can get samples of connectors from both organizations. Molex is much better equipped for getting samples though. There are some things to like about JST as well.


I am all about samples. It would be nice to try out some of the ones I didn't order yet. Do I just call their toll free number and tell them I am interested in their Micro-fit 3.0 connectors?

I haven't heard about the JST brand. I wouldn't mind trying some of theirs as well. I hadn't heard about Molex either until last week when reading the Ord Wiki on wiring and found Bart's recommendations about using them. It really makes a tidy wiring job. Wish I had known about them for other projects.

I am kicking myself for not reading the mouser page more thoroughly before hitting the place order button. At any quantity below 100, one of the pins was $0.28 each. At 100 and above, they are $0.07 each. I ordered 70 for almost $20. DOH! I could have 30 more for $13 less. :oops: :oops:
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Re: Stepper motor wiring: Shielded or Unshielded?

Postby flickerfly » Thu Oct 10, 2013 12:42 pm

For molex, look up the part you are interested in and fill out this form:
http://www.molex.com/molex/smp/amesamplereq

I suggest using part numbers ones on their website, not ones in PDF documentation. PDF documentation seems to include part numbers for things they never actually sold, maybe just theoretical.

For JST, do the same thing with this sample form:
http://www.jst.com/home10.html

They do have limits on the numbers for both orgs on what and how many of the parts you can receive. I used our hackerspace name as the business and have been sharing them around the space, showing them off and generally building connector awareness. :D
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Re: Stepper motor wiring: Shielded or Unshielded?

Postby jammer » Fri Oct 11, 2013 7:08 am

flickerfly wrote:For molex, look up the part you are interested in and fill out this form:
http://www.molex.com/molex/smp/amesamplereq

I suggest using part numbers ones on their website, not ones in PDF documentation. PDF documentation seems to include part numbers for things they never actually sold, maybe just theoretical.

For JST, do the same thing with this sample form:
http://www.jst.com/home10.html

They do have limits on the numbers for both orgs on what and how many of the parts you can receive. I used our hackerspace name as the business and have been sharing them around the space, showing them off and generally building connector awareness. :D


Thanks! I will be sending those forms in to get some samples.
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