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  • cable sheath

    I bought some 'spring sash rod' today. This is basically a flexible curtain rod, which you slightly stretch across a doorway or whatever to hang a curtain from. At any rate it's just a very long spring with a vinyl covering. Some of this stuff has an ID of just over .063, so a 1/16 diameter wire rope can be inserted through it. Makes a handy cable sheath.

    My spray booth project required me to remotely operate a couple of sliding gates to open or close the vents, and this is what I used. Turns out the cable I wanted to use has an OD of .066 and is just a tad too tight. Some other cable I found measured .063 and that worked perfectly. Just for gits and shiggles I went to Rona and measured the cable they sell there- .063, so I know that will work with this sash rod.

    This isn't the first time I've used this method to handle a cable actuation. It does work well and I've had no issues with it- other than the too fat cable that I tried to use. Of course I lubed the sheath and the cable as I was assembling it.
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

  • #2
    Bicycle cable sheathing jacket and cables are purpose made for pulling on things. And the insides of even average jacket brands is a slip tube of slippery plastic lining. The jacket for bike use is also designed to work in compression too. Curtain sash spring stuff won't be.

    So my own druthers would be to hit up a bike shop as long as the 2 meter long bike cables are suitable. Or if you can get a lighter cable that matches bicycle size, which is 0.059 from a quick check, then you could use that. Or take along some of your .063 cable and try it in some brake jacket.

    On the other hand it doesn't "push" worth a hoot. But then neither would the cable with your sash spring option. So the return spring needs to be at the far end of course.
    Chilliwack BC, Canada

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    • #3
      Originally posted by BCRider View Post
      On the other hand it doesn't "push" worth a hoot.
      If you replace the braided cable with a solid wire, like piano wire or similar, it will push quite well. Just be sure the wire end is nicely deburred, and the housing straight, before pushing it through.

      For those who don't use it, the good stuff has a teflon liner. The cheap stuff is really quite good these days, and is dirt cheap. It's useful to keep some around, and cut it as needed. Fwiw, the brake cable jacket tends to be spiral wound and is good for general purpose use. Cable jacket for index shifters is more special purpose, and probably isn't what you want.

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      • #4
        Brake housing is made of the outer sheath.. usually black, andspiral wound steel perpendicular to cable, and then an inner sheath for the cable to glide through. Old friction shift housing was basically the same. All shift housing now is the same as above but with the steel liner being individual 'wires' running in line with the cable (actually a very mild spiral). The forces in shifting housing is very light, and it needs to be stiff for accurate shifting. Brake housing sees considerable forces. If you run shift housing on a brake, when the brake is really applied hard, the housing will split open.

        Motorcycle shops have housing as well.. bigger scale than bicycle.

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        • #5
          Originally posted by Glug View Post
          If you replace the braided cable with a solid wire, like piano wire or similar, it will push quite well. Just be sure the wire end is nicely deburred, and the housing straight, before pushing it through.

          For those who don't use it, the good stuff has a teflon liner. The cheap stuff is really quite good these days, and is dirt cheap. It's useful to keep some around, and cut it as needed. Fwiw, the brake cable jacket tends to be spiral wound and is good for general purpose use. Cable jacket for index shifters is more special purpose, and probably isn't what you want.
          Throttle cable on mowers etc is "push/pull"cable that has a solid core. Bicycles are just a special case where the spring loading exists to pull back and avoid the need to "push". That is generally because the path the cable has to take may not be as suitable for the wide curves needed with solid core cable, as well as the need to follow the steering.
          CNC machines only go through the motions.

          Ideas expressed may be mine, or from anyone else in the universe.
          Not responsible for clerical errors. Or those made by lay people either.
          Number formats and units may be chosen at random depending on what day it is.
          I reserve the right to use a number system with any integer base without prior notice.
          Generalizations are understood to be "often" true, but not true in every case.

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          • #6
            Interesting idea. Thanks for sharing.
            Paul A.
            SE Texas

            And if you look REAL close at an analog signal,
            You will find that it has discrete steps.

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            • #7
              Good point about the larger motorcycle sizes.

              And if the bends are kept fairly generous the music wire instead of the cable could work neatly. Do take some care to ensure the load isn't too high though or the wire can buckle.
              Chilliwack BC, Canada

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              • #8
                Could a MIG welder liner do the job?
                Location: The Black Forest in Germany

                How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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                • #9
                  Originally posted by Black Forest View Post
                  Could a MIG welder liner do the job?
                  Not by itself I'd suggest. The spiral wrap wire would need an outer supportive jacket to avoid getting easily kinked. Also the ID is for smaller wire than one would want to use for a push and pull use.
                  Chilliwack BC, Canada

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                  • #10
                    I've got a couple of electrically operated vents. They automatically reverse (open/close) whenever AC power is applied. In other words; shoot 120vac to them and they open. Shoot 120vac to them again after an off cycle and they close. One is an 8" and one is a 12". I don't know what they cost MSRP since I got them for pennies at a salvage yard. They were brand new and still in boxes. I'm pretty sure they were for HVAC systems.

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                    • #11
                      I've been playing in this sandbox for decades building large puppets. You can buy 30m rolls of the 5mm brake housing if you want. I've used the motorcycle sizes like 7 to 10mm for pedal powered systems holding up to 1/8" cable. You can get push systems to work by playing with the cable construction. 7x1 cable will push nicely, 7x7 might depending on the housing and load, 7x19 will not.

                      When I was just getting into this stuff I was looking for miniature housings, and called up a small spring making company in Manhattan, when there were still such companies there. They said sure, come on up, and I did. When I got there he reached up and pulled a box off the shelf marked "Henson". Muppets had gotten there before me! It was sweet 1/8 OD extension spring in long lengths, that you could heat shrink a cover on to make a housing. Later when I worked for Henson I found they inserted teflon tubing too. Sadly that springmaker is long gone, the machinery was totally cool to watch, real hypnotic. Now, when I need real small housing I just used 1/8 od 1/16 id teflon, or even 3/16 od 1/16 id which is more flexible than 4mm bike housing.
                      Location: Jersey City NJ USA

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                      • #12
                        .....he reached up and pulled a box off the shelf marked "Henson". Muppets had gotten there before me!......
                        As a super avid fan of the Muppets and Henson's talent that comes through in a lot of other movies with puppets all I can say is that for me that is the best side story in this thread ! ! ! ! !
                        Chilliwack BC, Canada

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                        • #13
                          Originally posted by BCRider View Post
                          As a super avid fan of the Muppets and Henson's talent that comes through in a lot of other movies with puppets all I can say is that for me that is the best side story in this thread ! ! ! ! !
                          Here you go, like most of us I'm a packrat and still have that box 30 years later, since I never used up the springs. I barely got to meet Jim, he died like 3 months after I started.

                          Last edited by gellfex; 01-22-2019, 10:40 PM.
                          Location: Jersey City NJ USA

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