Shielding wires

newtothis
Posts: 125
Joined: Wed Feb 04, 2015 6:10 pm
Location: North Suburbs of Chicago

Shielding wires

Post by newtothis » Sun May 17, 2015 4:20 pm

This has come up in a few places and it seems there are two camps. Shield or Don't Need to Shield.

This questions is for the pro Shield-ers since I am planning to shield mine right from the get go vs discovering it might be a problem later and retrofit. No harm in Shielding other than to my wallet and time. Going to use copper tin braided expandable sleeve I found on Amazon.

Would you shield all wires? Steppers, USB, power lines, limit wires, etc or just steppers?

Super dumb question: I think I need to solder a ground wire to the end of each shielding sleeve and then attach that ground to one of the grounding points on the Carbide board? Not sure. Do I also need to connect a grounding wire upstream lets say to the stepper motor or is having a ground wire simply attached to the shielding sleeve fine. I'm not an EE so I have no idea.
Shapeoko 3 #304

WillAdams
Posts: 8576
Joined: Mon Apr 09, 2012 6:11 pm
Location: Pennsylvania --- south of the Turnpike, East of US-15
Contact:

Re: Shielding wires

Post by WillAdams » Sun May 17, 2015 4:39 pm

We have a bit on the wiki: http://www.shapeoko.com/wiki/index.php/ ... #Grounding and the following section.

I believe it's good to shield the stepper wires --- cuts down on electrical noise and reduces the possibility of interference from the high voltage connections. Shielding the limit switch wires seems like a good idea too, though it adds a lot of bulk.

For grounding, yes it's fine to ground things --- at the controller end only. You should be careful to insulate things at the other end, since one doesn't want to create ground loops.

That said, I'm currently running un-shielded, ungrounded stepper motor and limit switch wiring on my SO3 and it seems to be working fine in early tests. Waiting to tweak my Z-axis before more extensive testing.

My SO1 has shielded wiring, but I haven't found time to properly ground it yet.
Shapeoko 3XL #0006 w/ Carbide Compact Router w/0.125″ and ¼″ Carbide 3D precision collets
Nomad 883 Pro #596 (bamboo)

rtlflatt
Posts: 178
Joined: Sun Jan 18, 2015 2:11 am
Location: Bay Area, CA

Re: Shielding wires

Post by rtlflatt » Sun May 17, 2015 4:43 pm

dont attach shield to machine side. and dont attach to controller ground. so leave floating i guess? i seen multiple suggestions on this. maybe tie shields together? might have to experiment

i bought some of this to avoid cutting connectors.

edit: WillAdams is a jedi ninja. does he even sleep?
Shapeoko 3 #??? (Missing serial plate?)
Lulzbot Taz 5 (Heavily modified)

newtothis
Posts: 125
Joined: Wed Feb 04, 2015 6:10 pm
Location: North Suburbs of Chicago

Re: Shielding wires

Post by newtothis » Sun May 17, 2015 4:48 pm

Thanks Will. I'm the guy who will add 1-2 more screws into the wall when hanging a shelf. I'll almost always go for heavier gauge anything - Winter coats, wires, screw size, straps, etc... So yes this might be overkill but then if I didn't...nevermind...I can't imagine that at all.
Shapeoko 3 #304

WillAdams
Posts: 8576
Joined: Mon Apr 09, 2012 6:11 pm
Location: Pennsylvania --- south of the Turnpike, East of US-15
Contact:

Re: Shielding wires

Post by WillAdams » Sun May 17, 2015 5:15 pm

I think that shielding would be too much of a good thing, unless covered w/ some sort of tubing or other insulated protection anywhere it might contact the machine.

While problems from electrical interference are bad, ground loops seem to be even more insidious and difficult to ferret out --- I'd forego shielding rather than directly create such.
Shapeoko 3XL #0006 w/ Carbide Compact Router w/0.125″ and ¼″ Carbide 3D precision collets
Nomad 883 Pro #596 (bamboo)

rtlflatt
Posts: 178
Joined: Sun Jan 18, 2015 2:11 am
Location: Bay Area, CA

Re: Shielding wires

Post by rtlflatt » Sun May 17, 2015 5:57 pm

WillAdams wrote:I think that shielding would be too much of a good thing, unless covered w/ some sort of tubing or other insulated protection anywhere it might contact the machine.

While problems from electrical interference are bad, ground loops seem to be even more insidious and difficult to ferret out --- I'd forego shielding rather than directly create such.
i plan on putting heat shrink over the whole thing. i think it should work just as well as shielded wire. once so3 gets here ill test with and without this tube shielding. i have access to a fluke scopemeter so ill try and get some usable data posted. if it works as well as i think it will these would be a great option for shielding wires without needing to find the right size connector/pins and cutting connector off and it only cost $0.50/ft
Shapeoko 3 #??? (Missing serial plate?)
Lulzbot Taz 5 (Heavily modified)

WillAdams
Posts: 8576
Joined: Mon Apr 09, 2012 6:11 pm
Location: Pennsylvania --- south of the Turnpike, East of US-15
Contact:

Re: Shielding wires

Post by WillAdams » Sun May 17, 2015 6:18 pm

_That_ will work. Looking forward to seeing your build, and esp. hope you'll post your analysis of the electrical noise implications.
Shapeoko 3XL #0006 w/ Carbide Compact Router w/0.125″ and ¼″ Carbide 3D precision collets
Nomad 883 Pro #596 (bamboo)

lordmundi
Posts: 207
Joined: Wed Jan 01, 2014 4:02 am
Location: Friendswood, TX
Contact:

Re: Shielding wires

Post by lordmundi » Sun May 17, 2015 9:04 pm

my limit switches were completely useless when first hooked up with almost 3V peak-to-peak noise coming down the lines. I'd say if you don't have some sort of active noise filtering on your limit switch lines, then you will definitely want to shield. If you have an interface circuit with some optoisolators or something like that to help be immune to noise, then you may not need shielding.

after getting so frustrated with noise, I've got a circuit now to hook up my limit switches with and filter the noise, but I still haven't gotten around to trying it out. I think this missing circuitry is the biggest oversight of the G-shield and units that are shipped. Its one reason I'm excited about the new all-in-one controller from inventables. That's the sort of thing that should have came with the machine all along.

WillAdams
Posts: 8576
Joined: Mon Apr 09, 2012 6:11 pm
Location: Pennsylvania --- south of the Turnpike, East of US-15
Contact:

Re: Shielding wires

Post by WillAdams » Sun May 17, 2015 9:08 pm

The Carbide Motion 3D all-in-one control board also addresses this I believe: http://www.shapeoko.com/wiki/index.php/ ... trol_board --- isn't that's what's meant by:
buffered inputs
Nice to know that Bart Dring, who designed the buildlog.net stepper shield (not gShield --- thanks for the correction) got it right w/ the X-Controller.
Shapeoko 3XL #0006 w/ Carbide Compact Router w/0.125″ and ¼″ Carbide 3D precision collets
Nomad 883 Pro #596 (bamboo)

cvoinescu
Posts: 4442
Joined: Thu Jul 19, 2012 6:50 pm
Location: Camberley, UK
Contact:

Re: Shielding wires

Post by cvoinescu » Tue May 19, 2015 2:24 am

Bart Dring did not design the gShield. He designed the buildlog.net stepper shield (it takes four Pololu driver modules).

As far as I can tell, the Carbide Motion board has pull-ups, low-pass filters and Schmitt trigger buffers on its limit switch inputs. You can't really ask for more.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

Post Reply