Quote:
Originally Posted by DampRobot
Could someone (Adam?) go into a bit more detail about rigging the cabling in an elevator? For example, what type of cable is best, how do you deal with tensioning and stretching, and how do you tie it off the best? What are good ways to attach the cable to the drum, how do you keep it from getting tangled, and what are good ways to do pulleys?
I'm also not 100% clear on how to do the Constant Force Springs. What's the best way to mount a CFS, and what are some of the better suppliers for CFSes? Also, I've had mentors try to dissuade me from using a CFS because it's basically a razor blade under 40 lbs of tension. Are CFSes safe to use, and what's some advice about setting them up safely?
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We used 1/16" steel cable in 2007. It sucks. working with it is miserable. You will end up with bloody fingers every time you touch it.
Since then we've used Dyneema. It is tremendously strong (used in sailing), lighter, and easier to work with. There is a certain type of knot that you have to use to avoid reducing the strength of the line dramatically at the knot. I don't remember what knot that is, but someone else may be able to chime in here.
In a continuous elevator you want to mount it to the carriage with some kind of spring element (we've used springs, or bungee cords, but a bungee cord doesn't last very long).
For attaching to the spool I want to say we tied a loop in the end of the line, big enough for a 10-32 screw to pass through, which we screwed into a drilled/tapped hole in the plug holding the two spool halves together...but my memory isn't that great.
We've never had an issue with tangling and don't do anything special to avoid it.
Constant force springs aren't dangerous until you load them out of axis or try to unroll them a little to made the ID fit something not quite nominal. If you do, you're asking for them to unwind and cut you. It's happened to us once and it wasn't pretty.
You can find a lot of info about counterbalancing (and some detailed pics of our elevator)
here
There are other interesting ways of doing elevators that are quite elegant such as 971's use of belts.