straightening thick wire?

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hodad

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Jun 4, 2004
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I'm working on a project (Wurlitzer sustain pedal) that requires Bowden cable.  I picked up something relatively lightweight at the auto parts store--seems like it'd be a lot easier to work with than the heavy duty stuff I got from the aircraft supply place, except the damn cable was coiled so tightly that the inner wire has some major curves in it, & I can't figure out how to get it really straight.  The curves really impede the movement of the wire through the outer sheath, which is unacceptable in this application. 
Or am I better off just buying some new/better/less curvy wire?
 
Simple.
Clamp one end of the cable in a vice. Uncoil the wire.
Next, take a cotton cloth/duster and grasp it tightly over the cable at the vice end.
Firmly draw the duster over the cable length, repeat over and over until the cable
uncoils and straightens.

Don't be frightened to use muscle!


Frank
 
If you go to a good bicycle shop you can get cables that have been ground-smooth and teflon coated, that run in a housing with a Teflon liner-tube, for around $15.00
Very smooth.
Two different thicknesses, as well (brake, derailleur) ;)

-Eric
 
+1 on the bike shop cable.  I bought some for my Wurly years ago.  Certainly less expensive than the custom online place.  Unfortunately I haven't taken the time to install it. I was more worried about exact lengths and securing the end connections.  Doesn't look like sheath friction would be a problem because of the teflon coating Eric mentioned.
 
I am with Frank. I like straightening things up ;D

Straighten it by hand as much as you can Then wrap a bit of cloth over a table leg so that it does not damage the sheathing. Push and pull the wire over the leg until it is straight.
 
I can't quite manage to get it seriously straight, but it dawned on me tonight that it might work out if I used the thin inner wire with the larger outer sheath of the heavier duty Bowden cable.  I'm thinking this might do the trick.
 
I use the same vise as mentioned, but I twist the other end around the duster handle or a large screwdriver or a rebar and stretch it with body weight.  I do this with sterling silver wire for jewelry and copper for electronics.  I can get up to 8 GA straight that way.  If it is too stiff for the application after, I anneal it with a torch.  Seems like you want it finished stiff.
If your body weight is not enough, go Greek.  Use a fulcrum.  Use a longer bar to get some physics into it.
And maybe you should anneal it first if it is very stiff.
Mike
PS: what gauge is the wire, anyway?  For electronics 10 GA is the largest usually, and the tug-of-war with the vise is fine.
 
sodderboy said:
PS: what gauge is the wire, anyway? 
Not wire --stranded-steel cable. ;-)
http://en.wikipedia.org/wiki/Bowden_cable
Bowden was the founder of Raleigh Bicycles --for those of us old enough to remember them ;-)
 
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