[SML] Automating Single-purchase

[Bruce Cooper]

On Tuesday, July 26, 2016 4:01:07 PM CDT, Ed Hills via Stagecraft wrote:
> ​Hello All-
>
> What would be the challenges, as you see them, in moving a single purchase
> lineset off of a motor and a drum/mule/wench?
>
> It seems like such a simple idea.  Just replace the hemp with a longer
> piece and take 3 or 4 wraps around the drum to move the line.​
>
> Add steel, gear motor, and control.
>
> There must be pitfalls

Slippage due to stretch or relaxation causing inaccurate encoder feedback. 
Tensioning problems due to same stretch/relaxation. /Wear on the [I assume 
3-strand] operating line as it isn't allowed to twist and flex as it 
normally does to equalize the load on the strands.  Compression fatigue 
damage to non-3-strand ropes [most of the handlines in use today aren't 
intended to be run around metal drums].

  I'd see about just attaching the end of a steel or proper synthetic winch 
line from the winch to the bottom of the arbor and leaving the system a 
little pipe-heavy.OR Alternatively getting a proper roll-on/roll-off 
automation winch and running to both top and bottom of the arbor IN PLACE 
of the handline.

My thoughts only, but I would avoid using the handline at all in automating 
a lineset.

:Bruce Cooper
--
Wandering Suntanned Stagehand.