Quote:
Originally Posted by lbarger
Others have addressed cable/chain routing so I will not. Besides when my team did it we used something close to 22 ft of chain for an 8 ft lift. (Not at all efficient routing.)
What I will bring to the discussion is full extension draw slides. They are on the heavy side but made for extending. Nothing to build, just drill holes and mount. What they cost in weight is made up for in simplicity, availability of spares and speed of assembly. Think about side loads and getting hit with them up when looking at load ratings.
Also think about how you will determine full extension or retraction. Our system had a shuttle that ran up and down a tract on the top stage and two sets of draw slides on aluminum tubing to get to 8 feet. With binding, any stage could move or stick during the lift. We counted stripes on the drive axle to determine amount of motion. This was great accept we could not get the controller to remember the position between restarts. This was solved with a home switch in the lowest possible position for the upper stage of the lift.
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That sounds very similar to what we considered. We could have used an encoder in the toughbox (relative) with a home switch at the bottom of travel, however we opted for a 10-turn potentiometer riding on the bottom chain so that we had an absolute value and could minimize wiring.