Moving object on a curve

Hi,
I want to move a piece going up, and coming down on an arc surface as shown on the attached sketch.

An Arduino Mega control the step motors to go up and down as well as any necessary stops.

Since this is not a straight line, but a curve, I was thinking to use a cable to do this because the cost of a curved metal gear that size is prohibitive.

Do you know of any mechanical system that I can attach to the Stepper shaft that will allow me to wind the cable and pull the piece ?

I tried to find this but didn’t find anything, so may be a member of this community would have an idea where I can find this.

Even if this is not really the right forum, thanks for any help.

Have you thought of a 1200mm counterweighted arm? Then you could put a stepper (or servo) on the axis of the arm.

If you use a cable could you not run the cable in a loop and use only one motor?

I hope there is a curved track on which the "piece" runs.

Yes the piece is supported by Rollers on 2 tracks.
Actually the one stepper pulling up could be a solution, and gravity would make the piece going down easily as it is around 10kg.
Now the problem is to find something reliable to roll the cable nicely.

A garage door cable drum might work nicely. Or wind the cable around the threads of a large diameter bolt.

http://www.google.com/imgres?imgurl=http%3A%2F%2Fdiy-garage-door-parts.com%2Fwp-content%2Fuploads%2F2013%2F04%2FIMG_7174.jpg&imgrefurl=http%3A%2F%2Fwww.diy-garage-door-parts.com%2Fbuy-online%2F7ft-torsion-cables-332-quieter-than-18-cables-less-cable-rubbing%2F&h=600&w=900&tbnid=jZVgPqvjDyRIbM%3A&zoom=1&docid=VRKA0-5D85XJFM&ei=8XqSU_zLA4yvyAShpYHACg&tbm=isch&ved=0CAoQMygCMAI4ZA&iact=rc&uact=3&dur=3181&page=6&start=86&ndsp=19

Thanks all.

lou123a:
Do you know of any mechanical system that I can attach to the Stepper shaft that will allow me to wind the cable and pull the piece ?

Why not toothed belt, such as T2.5 or MXL? Works for lots of motion control systems. You might have friction
issues with the curved surface though as belt is rubbery.