What is the best type of wire to use in a high vibration application?

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Mbira

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I need to use relatively thin gauge wire - about 22 gauge is the biggest I can go...

These wires will be in pairs (positive and ground).  They are attached with this molex connector, so there is a good positive lock:
http://www.mouser.com/Search/ProductDetail.aspx?R=502352-0200virtualkey53810000virtualkey538-502352-0200

The wire will be about 3" long and will be attached on both ends and moving in all 360 degree directions.  The wire is attached to a marimba bar that is being struck, so the key bounces up and down and side to side a bit as it is struck.

Am I better off using stranded wire or solid wire?  Ribbon cable? Twisting the pairs together?  I think that eventually these joints WILL fail, and so I am planning on making these wires relatively easy to replace and making backups so they can be switched out as they break, but it'd make my life easier if I can find a solution that will work at least a couple months of regular action...

Edit: a little googling is telling me that stranded is what I want with vibration.  I'm still not sure if I'm better off twisting the pairs or keeping them seperate...



 
22 ga will be expensive

what you want is multi-strand wire,

however, not just any ol mult- strand wire,

what you need is a special multi-strand with about 104 strands in there, instead of 20 strands or similar.

this wire is hard to find, but it will last far longer than the regular wire for this application.

wire companies go in and out of bidness so fast, this means i have no source or ppart number, you will have to do some digging,
 
What is used in aircraft? From what I understand, PTFE-insulated wire was changed for Kapton because PTFE gives off nasty fumes when incinerated. If I want mechanical reliability, I go with silver-plated / PTFE-insulated wire. I specialise in servicing these units which were made in the early '80s with PTFE / Ag wire - I've yet to see a failure from the wire, even on really beaten up units - whereas everything else fails.

Justin
 
Check out flexible ribbon cables. Some has 1 million operational life.

In fact, poke through old printers. You'll get plenty of it.
 
CJ said:
what you need is a special multi-strand with about 104 strands in there, instead of 20 strands or similar.

Anyone know the name of this type of wire?  I'm searching for "high-density" and multi-strand, but not finding anything yet...
 
I second JR's speaker leadout braid (from the cone to the terminals) and CJ's multi-multi strand stuff.

A easy to find substitute for speaker leadout braid is Desoldering braid.

But where the connection will fail is at the Solder Joints where the flexible stuff suddenly becomes hard.  In speakers, we often gunk the joint with Silicone Rubber Sealant  tapering nicely along the braid.
 
Just occured to me . RC servo extension leads would be suitable for this. They are very finely stranded, extremely flexible and long life. I have been using them on my robot arms.  Hitec is a good brand.
 
Seriously, is there any other way that vibrational information can be transmitted rather than copper?  If not maybe the contact/wiring used in cardio electronics might be worth investigating.
Mike
 
sodderboy said:
Dude, like, you have robot arms?  Where's the pix? 

Arms, wires, everything : )

Mike


Hi Mike,

http://www.robotica.co.uk/robotica/ramc/products/robotic_arms/edubot250.htm

It is really a desktop educational tool that I sell generally to universities, but I have some customers using it for simple pick and place applications.  However, the web site and the product is very old now.  In the new year I'll bring out a new design with sophisticated controller.
 
Google for wire that has been approved for use in aircraft as someone else has mentioned.

Any wires/cables that have FAA cert 8190-3 are deemed  'Airworthy' and have literally been twisted and tweaked until failure to satisfy the FAA.

You may want to call up some FAA certified repair stations that deal in 'return to service/airworthy' and fish them for which cables they use in communication equipment headsets mics etc.  You then should be able to determine the supplier of said cable, and you should be able to obtain it from a vendor/supplier. 
 
sahib said:
RC servo extension leads...

That was a damn good suggestion.  I found this:
http://www.bphobbies.com/view.asp?id=A0320179&pid=T434208

22awg and 60 strands....and a good price.
 
If you want vibration resistance, you want something like loudspeaker leadout braid (eg desoldering braid).  You need MUCH more than 1 million cycle life.  1 million cycles is  less than 17min at 1kHz.

I'll repeat that failure will occur at the joints so if you want it to last, you'll have have to gunk the connections with flexible silicone sealer.  Stuff it into the Molex. 

Don't twist the leadouts as that will add stiffness & be more prone to failure.
 
Hi Ricardo,
These are marimba bars, not speakers vibrating at 1kHz.  The pickups are on the nodes, and I'm mainly dealing with the vibration of the bounce of the bars going up and down when struck-the bars that are breaking are the ones that are being struck the most in performance right now.  I like the idea of desoldering braids, but it would be a pain in the ass too because I would need to shrink-tube them and then get them to fit in these little 22awg size molex cables...I'm going to try this wire first and if the wires last more than 2-3 months of extensive playing, I'll be happy because I can make up a bunch of them and swap them out on stage if and when they break.

I'll definitely take your advice on the silicone sealer, thanks!

Any thoughts from anyone if I should just get a crimp tool and crimp without soldering or solder as well?  I've always soldered, but not sure if this application is different...
 
Would attaching to the resonators work instead?

Another thought... If there was some way to attach little pieces of ferrous metal to the bars, like a thin slice of steel circular stock on each bar, then a magnetic pickup could be used (although fidelity?) that is detached from the vibrating bars completely....  One large pickup like a clavinet pickup maybe... I dunno thinkin' out loud here...  might be half baked... gets rid of the vibrations on wires issue though if it would work...


 
The resonators are separate from the frame and keys, so would be a pain to connect every gig...well that's not totally true-it'd just require a different design than what I have currently happening...

The pickup idea is interesting...there is a space that is about 1/4" between the bottom of the key and the frame where there is foam rubber.  There is a space there where you could have a pickup.  I don't have any experience with winding my own, but I do want to be able to account for velocity when striking the key, and some keys bounce more than others depending more on size of the key than on velocity of the strike, so it may be a lot more work...

I'm going to see how this new wire works first-it's by far the easiest solution if I can get the wire to last...
 

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