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Thread: Need ideas for a drag setup

  1. #1
    Join Date
    Mar 2019
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    Lightbulb Need ideas for a drag setup

    I need to introduce drag to a nylon line without friction which would damage the line. I initially thought of using a roller to wind the line around as shown in the mock-up below:



    Problem is the line "walks" in the direction of the wind and eventually hits the end of the roller causing it to bunch up and overlap... Ultimately the line will be wound a few more times around the roller and will have about 50lb of tension on it.

    Here's a video showing the "problem":
    https://photos.smugmug.com/photos/i-...S8Lnc-1280.mp4

    Any ideas how I can improve on this?

  2. #2
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    Default

    Make the middle section hollowed out a bit. Like a reverse crown on a tracking wheel. Line guides closer to the tension spool might help keep the input, and output corralled a bit better but the middle might still walk around a bit.

  3. #3
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    Could use a rubber pulley attached to a small dc motor and use a rheostat to vary the load on the motor. The motor will act as a generator to keep the tension.
    Helder Ferreira
    Setúbal, Portugal

  4. #4
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    Would an eye hook type of guide on the entrance side to the white spool introduce too much friction?
    How to become a millionaire: Start out with 10 million and take up machining as a hobby!

  5. #5
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    How much tension do you need? Can't you just simply put some drag on the spool itself? That would work for a light amount. But if you need more tension than that the line might start cutting down into the strands below.

  6. #6
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    You could make a section of thread on the spool for the line to follow. Then it would always go on and off in the same place.

  7. #7
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    Try a ruby wire guide, many on wire edm machines, also embroidery machines sewing etc, about $10 little tube with a ruby with a hole.
    Mark

  8. #8
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    Simple... Add more than one roller. Two might be enough and you can split the drag among the rollers so each roller adds more drag vs. one roller with all of the drag.


  9. #9
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    If you don't want friction, why do you have two sewing machine tensioners. Those can get pretty warm if passing a lot of line. A little over the top for just guides.

  10. #10
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    You apparently need multiple turns so the roller can exert enough drag without the line slipping on the roller. Multiple rollers each with a small drag is a neat solution but the amount of drag each roller can exert is limited because there is less than a turn on each roller per the drawing above.

    You can improve things by increasing the wrap angle so it is closer to 360 degrees on most rollers. Plus, adding a V groove will help by wedging the line into the groove (as in my gearless clock) to further increase friction.

    Depending how often you will be threading the line through, you could use multiple V grooves on each roller and thread the line through so it makes multiple single wraps on the rollers - this will take some thought to get an easy pattern such that the line travels in the same direction each time it passes over a roller. Probably not useful if you will be reloading the line often.
    Last edited by GadgetBuilder; 04-04-2019 at 01:57 PM.

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