thats what I was fist thinking. i too have been thinking about open circuits caused by the limit switch.Yes mate, you have nailed it. Depends on how you want to control it, you could fire it for a period of time from a timer, or use limit switches to turn it off. Just depends how 'smart' your timer is.
Switches are simple devises though, you can get them from all kinds of places, fridges, car door (int lights) and so on. The tricky part with those is the re-start. A switch has power when closed and not when open, so the devise hit the switch, open circuit and devise has the power cut, but when you want it to move again the switch is still in the open position. I feel that the re-start will be the tricky part to overcome, certainly not impossible though. I will try have a think about it and do that drawing I was thinking about yesterday. That three position window switch you were thinking about might work as a 'on-off-on' deal, but I don't think it will change polarity. I need to look into that some more.
If you decide to look at the timer, given the stroke speed you may be able to do it cheaper than first thought. I picked up this unit from Bunning's to run a fan on and off in my still air. It is as fine as 1 minute (no seconds). If you have a 1 or 2 minute cycle, it could handle them easily, every day.
Features include,
7 day pre program,
20 setting per day (20 on and 20 off)
1 min accuracy
battery back up
and mains outlet
$13.90
http://www.bunnings.com.au/products_product_excalibur-7-day-mini-digital-timer_P7050097.aspx
You could set this to fire for 1 minute every 2 hours via a reversing relay. Without testing it, I would think that it would travel in one direction for a set time, then the other the next time the timer starts. Clean and easy. If you hunted about you might be able to get the same style plug in timer that can handle 30 second increments for a few bucks more.
I could run it a minute out, a minute back but in the center of the actuators reach - eliminating the need for limit switches to control the stop. I can adjust the effect on the turner by placement along the fulcrum