Posted: Tue Nov 04, 2008 9:50 pm
Hi Glen,
some suggestions from one who has built an operating winder
http://www.carendt.com/scrapbook/page57a/index.html
OK lets work on correct positioning first.....
1 - Eyeball control - This has several limitations as I found out with Jaxcilliest - the most difficult problem is seeing when you have actually arrived at the top position because the cage, hoist structure, runners etc can form pretty effective view blocks.
2 - Physical barriers to cage travel - this works well for the lower level by simply placing a floor under the cage. This means when you throw slack rope on the winder you have arrived down below. This is what I used on the lower level on Jaxcilliest. For this to work on the upper level you need a motor that can be stalled out when the top of the cage fetches up against something solid placed across the shaft and the rope goes tight. It doesn't matter whether the rope streches or not, you will still finish at the same position each time. They definitely don't use this method in the real world.
3 - Limit switches on the surrounds - Here limit switches at each end of travel chop the power to the motor winder when the cage reaches them. This takes some setting up, but once it is set up the cage will stop at the same position each time. A suggestion is to mount the limit switches in an adjustable mounting (screw or on a taper) that can be adjusted until you get the right spot at each end of travel, then lock or glue the limit switches in position. Unless you use a seperate "striker" for the limit switches, the lower limit switch will be below the floor on your lower level. The striker can be as simple as a piece of plastic glued to part of the cage so that is protrudes out from the normal envelope of the cage.
4 - Limit switches on the cable - I'm not sure if you can use this one, but I have seen it work very effectively for the logging winch on Professor Klyzlr's former "9 Mile" layout. In this variation, a bead or a knot on the rope is used to engage 'fingers" on the limit switches. The fingers are wide enough to allow the normal rope to pass unhindered but are engaged when when the knot or bead reaches fingers and triggers the limit switch. This again chops the power to the motor on the winder.
For limit switches to work repeatedly and precisely, you need the speed of the cage to be a constant, so that the amount of overun is constant. Look at using a constant voltage to the motor on the winder. This will help eliminate another variable when you are setting up your limit switches.
On Jaxcilliest I used brass square section on the cage running in brass channels attached to the hoist structure. This gives low friction running surfaces, especially once the channel has been dusted with some powdered graphite.
I hope that this helps. Please let me know if you need detailed photos of any parts of Jaxcilliest.
some suggestions from one who has built an operating winder
http://www.carendt.com/scrapbook/page57a/index.html
OK lets work on correct positioning first.....
1 - Eyeball control - This has several limitations as I found out with Jaxcilliest - the most difficult problem is seeing when you have actually arrived at the top position because the cage, hoist structure, runners etc can form pretty effective view blocks.
2 - Physical barriers to cage travel - this works well for the lower level by simply placing a floor under the cage. This means when you throw slack rope on the winder you have arrived down below. This is what I used on the lower level on Jaxcilliest. For this to work on the upper level you need a motor that can be stalled out when the top of the cage fetches up against something solid placed across the shaft and the rope goes tight. It doesn't matter whether the rope streches or not, you will still finish at the same position each time. They definitely don't use this method in the real world.
3 - Limit switches on the surrounds - Here limit switches at each end of travel chop the power to the motor winder when the cage reaches them. This takes some setting up, but once it is set up the cage will stop at the same position each time. A suggestion is to mount the limit switches in an adjustable mounting (screw or on a taper) that can be adjusted until you get the right spot at each end of travel, then lock or glue the limit switches in position. Unless you use a seperate "striker" for the limit switches, the lower limit switch will be below the floor on your lower level. The striker can be as simple as a piece of plastic glued to part of the cage so that is protrudes out from the normal envelope of the cage.
4 - Limit switches on the cable - I'm not sure if you can use this one, but I have seen it work very effectively for the logging winch on Professor Klyzlr's former "9 Mile" layout. In this variation, a bead or a knot on the rope is used to engage 'fingers" on the limit switches. The fingers are wide enough to allow the normal rope to pass unhindered but are engaged when when the knot or bead reaches fingers and triggers the limit switch. This again chops the power to the motor on the winder.
For limit switches to work repeatedly and precisely, you need the speed of the cage to be a constant, so that the amount of overun is constant. Look at using a constant voltage to the motor on the winder. This will help eliminate another variable when you are setting up your limit switches.
On Jaxcilliest I used brass square section on the cage running in brass channels attached to the hoist structure. This gives low friction running surfaces, especially once the channel has been dusted with some powdered graphite.
I hope that this helps. Please let me know if you need detailed photos of any parts of Jaxcilliest.