This could be really useful. In Skyrise many teams wanted to run a shaft all the way though from one side to the other, but had to make couplers to make this possible. An 18" shaft would make this much easier.
I can definitely see where that would be useful.
Does VEX sell couplers for high strength shafts anyways?
No couplers for high strength shafts are avaialble (yet). The only way I could think of making a VEX legal coupler would be to broach out a 12-tooth metal gear and add a couple set screws. Alternatively, one could take a couple H.S. 36 tooth gears and a pair of 3-hole H.S. lock bars (available from robosource.net, ebay, amazon.com or VEX Team Virus), and bolt the whole assembly together to make a coupling. I can experiment with the 12-tooth gear, but I’m not sure if they would be strong enough to not break under torque (and they would cost about $6 by the time we made them). Please P.M. if there is some serious interest.
Using the clamp collar with two shafts halfway in would probably be better then trying to convert the 12T pinion into a coupler. Both are 1/2" wide but the clamp collar would be grabbing onto all 4 faces of the shaft at least while the set screw wouldn’t be enough to hold it well probably.
Really neither solution is very good. However, I’m not sure why you would ever need an 18" long shaft anyway. You’re just begging for there to be way too much flex and misalignment in the bearing holes.
18" long shaft to connect two sides of a lift together to reduce tilting? Scissor lifts were (and are) a nightmare. This year my team wants to power the entire lift off of a single gearbox, and 18" shafts would make it easier.
I would find a way to use aluminum structure pieces to do that (C-Channel, Angle, etc.). The shafts will just be wayyy more weight then needed and that’s not what their design intent is.
In robotics and industry in general you never want to use a shaft that long unless absolutely necessary. There just isn’t a need for it in VEX. I doubt VEX would ever sell it as it probably wouldn’t sell well; most would just use it as stock to cut down to a specific size which is generally how the 12" sections are used.
But I need to transfer power from one side of a lift to another. How would you do that with c-channel?
I thought you were saying you were connecting to arm linkages together. I would need to see an example picture to better understand what you’re saying.
They should make a converter for high strength shafts.