Light-duty tension cable needed. 3 to 5lbf. Small dia

[mrkram]

Am looking for a tension cable, similar to ones I've seen in inkjet printers (wrapped around a drive pulley and connected to the printhead carriage).

Details of this application:
- cable end is attached to a mechanical lever and button.
- when button is pressed the cable is pulled ~.25"
- the cable pulls a pawl from a locking mechanism.
- when the button is released,
a spring pushes the pawl back in position
- cable is ~20" long
- cable lives under negligible tension.
- cable is tensioned to 3lbf - 5lbf to pull pawl
- part life is 10K cycles
- cable wraps around very tight radii .030"-.060"
- negligible sliding friction
- crimped terminations may be attached at both ends

The cables I remember seeing were .010" - .020" thick. They were made of a white fibrous material.
Can someone please tell me how to find something like this on the web. Two of us have done web searches. But there are so many kinds of "cables" in the world, we can't find what we're looking for.

thanks!

 

[rb1957]

would fishing line work ?

 

[MintJulep]

Nylon, Kevlar, Spectra, polypropylene, polyolifin, dacron...

 

[mrkram]

Fishing line is good, as long as I can find a legitimate supplier in the business of cutting the fishing line to length and terminating the ends.

Will bring in some fishing line to make the benchtop prototype. Meanwhile, am still looking for a way to buy this part as a measured and terminated cable (like the one in the inkjet printer).

thanks!

 

[mrkram]

Thanks, MintJulip,

Any of those materials would work. My original post wasn't clear enough. I should have included I'm looking for a commercialized cable solution -- a fiber strand with eyelets at each end -- to make this project work.

 

[CoryPad]

Try here:

http://www.sanlo.com/mechanical_assemblies.aspx

They are part of The Courtland Companies, and they make metallic wire rope, nonmetallic rope, and assemblies with end fittings.



Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[MadMango]

I've had great success with Ver Sales here in Southern California.

http://versales.com/

 

[unclesyd]

Here is high fatigue resistance wire rope by Sava. They have two very good design guide downloads.

http://www.savacable.com/pages/prod_01_02.html

 

[minerk]

I've used

http://www.phillystran.com/index.htm

for larger Kevlar ropes. Not sure how small of an assembly they'll make, but it might be worth checking.

 

[MikeHalloran]

I've tried small Kevlar cables.. bought the ferrules and crimpers, the whole bit. Couldn't make the ferrules grip, and the cable frayed when bent at the recommended radius.

The best stuff for this job is 'dial cord', which used to be widely available, when radios had mechanical tuners. It doesn't stretch, and has a high-friction surface which makes it easy to drive and means termination can be done with a decent knot. I think you can still get it from electronics wholesalers, though it may take them a while to find it on the shelf out back.



Mike Halloran
Pembroke Pines, FL, USA

 

[griffengm]

mrkram,
As an out-of-the-box suggestion, try going to a sporting goods store selling fishing equiptment. Check out the "leader" or "wire leader" section. Your description sounds very much like these assemblies and they are made in sufficient volumes that there may be an off-the-shelf item you can use. Or try the same keys in Google.

Griffy

 

[unclesyd]

Here is the best if you want to try fishing lines. This particular one is translucent but they are ones that are of white. The off white is going out of style as more people are requesting invisible lines.

http://www.spiderwire.com/prod.php?k=74407&sk=50687&u=SUIB-125

 

[mrkram]

Thank-you Syd, Mike, & Griffy,

"Dial cord" was easy to find on the web. $.12/ft. The current design would have the cord sliding around a couple small radii (approx 90 degree bend around a .125" radius) on its path. Am concerned that the stickiness of the cable will cause it to wear quickly. Would need to do life testing before continuing.

A fishing leader would seem a good material, too. It's the same material as I found on the Sava website, suggested by unclesyd. The fishing leader would give me a terminated sample that we could life test quickly. Should be low cost if a fishing leader manufacturer could make a custom part for us. . . and it will be steel, which gives management some confidence. I like the SpiderWire suggestion, too. "80lb test" should be overkill. A bargain at $.06/ft.

Am still working on this. Will need to prototype some concept models in the next week or so. Will try some combination of materials listed above. May include dental floss/tape in the list of tests.

Thank-you all for your help. This topic has taught me some things about how to ask a question well.

 

[MikeHalloran]

Yes, the dial cord will 'stick to' a stationary post. Small nylon or brass pulleys are the way to make it turn a corner. They also used to be easy to find.





Mike Halloran
Pembroke Pines, FL, USA

 

[chicopee]

Be careful with some of the synthetic material, they'll stretch when wet or damp.