----- Original Message -----
From: Lee McLaren <lmclaren@tasnet.net>
To: pic microcontroller discussion list <PICLIST@mitvma.mit.edu>
Sent: Thursday, April 07, 2005 12:31 PM
Subject: [OT] How do you wind a wire rope around a drive wheel more thanonceand
not have it travel up the wheel?


> Hi,
>
> I am building a electric gate and are trying to use 4mm wire rope to
> pull the 4m gate in and out, my first attempt was a failure as I
> (mistakenly) thought that if I cut a groove in a pulley the right width
> for the rope that the rope would pay in and out in the same spot.
> I know how to get half a turn around the drive wheel by cutting a
> parallel groove but would like to get three if possible so it doesn't slip.
> I am using a PIC and rotary encoder to know where the gate is so I can
> accelerate and decelerate as quickly as possible, as the rotary encoder
> is on the drive wheel I can only tolerate a small amount of slippage.
> I have spent hours on the net trying to find the answer but don't seem
> to have hit on the magic search terms, I am sure I have seen this done
> with some sort of thread on the drive drum but might be dreaming it!
>
> regards
>
> Lee McLaren

Could you remove your need for multiple turns if you increased the tension in
the rope? If so consider using a weight, hanging from a pully wheel and placed
on the rope). The groove in the pully may actually need to be a sharpe V shape
two or three times as deep as the diameter of the rope.

Regards
Sergio Masci

http://www.xcprod.com/titan/XCSB - optimising PIC compiler
FREE for personal non-commercial use





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