cabling bundle method maybe called Raychem Lay 1

[cresbydotcom]

Hi
a colleague asked the question about laying bundles of wires in expanded mesh to form a "cable" so that all wires (or cables) get approx the same stress as the enclosed bundle is bent or flexed. These are 24AWG PTFE insulated types, Belden cables, STP PTFE &/or others

He thinks there is a pattern of partial helices or somesuch that works well. In a bundle where the connectors (Aerospace) are circular the middle wires would not normally flex as much putting strain on the outer ones. So some system to mix it up and not knot it or plait it is required.

He knows it as the "Raychem Lay" but maybe a search using a different phrase would do it.

Any phrases that spring to mind?

there is a tide in the affairs of man that you Canute ignore.................

 

[Trotski]

the lay of cables in a bundle is more of a concern electrially than to do with mechanical forces, a bundle should be supported so that stress is at a minimum and the lay of individual cables in a bundle is so that interference and crosstalk are also minimised

 

[mikeydidit]

The below thread will also give you an article that describes proper cabling methods. The main thing in the article that was a shock to us CG's was the fact that neat bundles were actually not recommended.
Read for more information.

thread575-1425391

Hell, there are no rules here - we're trying to accomplish something.
Thomas A. Edison

For the best response to a question, read faq690-6594

 

[cresbydotcom]

Thanks for the posts.

The links seem to be more concerned with crosstalk and impedance.

We are more concerned with mechanical stress. Theses might better be described as harnesses. Free statnding and connect test cabinet to Unit Under Test (UUT) and flexibility of the harnesses is important though they don't do much more than snake from the cabinet to the floor or bench. However failure of one wire is devastating - if it doesn't halt production it might invalidate the test (or go un-noticed for a while).

the UUT's are flight equipment. Test is on build, repair and maintenance over maybe 20 years life cycle.

there is a tide in the affairs of man that you Canute ignore.................

 

[Trotski]

you might be better looking at using the braided type cables such as used from the more flexible Patch cords, these would probably have a longer service life,
the various types of cables and suports used in Elevators and lifting epuipment could also suit your application

 

[ISDNman]

You might call a salesperson at Clifford of Vermont and discuss your needs.

They have cable for just about any use imaginable, and they can also make custom bundles.

Probably you simply need to buy the flexible cable used in robot arms rather than bundle multiple cables.

Even if you don't go with them I bet it would be worth picking the brain of their sales engineers.

Best of luck.

 

[cresbydotcom]

Thanks but we make cables
this one is for 20 years durability.
and it is handled daily.
Hence the concern.

there is a tide in the affairs of man that you Canute ignore.................

 

[mikeydidit]

One more thing comes to mind. I had a mobile MRI trailer that came in three times a week. I had to reconnect everything they needed every time they showed up and was concerned that moving the cables back and forth would eventually break one of them. I place all their cables in a liquid tight flexible conduit to protect them and to help cut down on EMI. They never had a problem.

Hell, there are no rules here - we're trying to accomplish something.
Thomas A. Edison

For the best response to a question, read faq690-6594

 

[cresbydotcom]

Hi again

We finally tracked-down the subject. Raychem don't exist per se and it took a few phone calls to Tyco to finally get hold of a man (from the Raychem days) who knows. We had a demo and it does need intruction.

He called them lay patterns

Basically it involved layering wires circumferencially. eg 1 inner, 5 helically wound over at a fairly easy pitch, a contra-wound kevlar tape (very thin 2mm wide) wide pitch, then the next layer contra wound so it does not fall into the "interstices". each layer has to be fully populated according to a table, filler/spare wires result. It presupposes all the same type of wire per layer in its simplest form.
And it definitely produces a bundle that is relatively stress-free.
Think under-sea cables and the copper & armour layer of high voltage distribution cables.

there is a tide in the affairs of man that you Canute ignore.................