What would be the best design for a chain elevator system for an arm? I don’t know very much about chain systems, but I have seen it used often in the FIRST Tech Challenge. Also what is the average height that a chain driven raising system can raise to. 
Thx in Advance,
Doombot
personally i find that the height is unrestricted, but the the number of stages that could actually function using linear slides is limited. i use a setup similar to:
http://www.vexlabs.com/conlift.shtml
and:
http://www.chiefdelphi.com/forums/showthread.php?t=41125&highlight=chain+lift+picture http://www.vexlabs.com/conlift.shtml
Thanks for the idea. Would you suggest using one chain kit or two?
i only have one right now, but i do need another, and also you may want to buy the vexlabs linear sliders to make the motion easier to create. i have 2 sets of these to allow for 2 stages
thanks man . you are so pro
I built one last year and it was a pain but when it wirked it worked great and when it sucked it sucked bad. I would suggest that if your moving a up a foot then buy 2 and 1/2 feet of chain or about 2.5 times your travel distance.
if you are going to use chain to lift this arm, I highly unrecommend it. Chain is used in bicycles and in motorcycles, but it is never used in high power machines like cars and trucks.
As said in the Inventors guide insert, Chain transfers 95% of the energy from the driving axle to the driven axle, but gears only transfer 85%. But the disadvantage for chain is that it slips very easily (especially the delrin chain that VEX sells). That means it would not work very well at all for an arm, and I would highly suggest gears (especially worm gears in the advanced gear kit, since they have such high gear reduction).
Another example would be the VEX Tomahawk, which uses chain a lot more than gears, since it’s designed as a motorcycle.
I’m not sure if I agree with most of what you’ve said.
As I’ve said before, it is dangerous to make broad engineering generalizations without any quantitative backup. They often prove to be false, and without grounding in reality.
Whenever you receive advice based on generalizations and opinion, it should be taken with a grain of salt. Your mileage may vary.
Important Considerations when Building a Chain Lift:
[LIST]
*]The Vex chain is made of plastic, and has a limited tensile strength. (If you pull on it too hard, it will snap.)
*]Using 2-chains in parallel means that each chain shares 1/2 the load. Using 3-chains in parallel means that each chain shares 1/3 the load. Etc… etc…
*]Vex Tank-Tread can be used as a “high strength” chain. It has a much higher tensile strength than the Vex Chain. (You can even cut off the tips of each tread-link to make it more compact.)
*]There are many different types of cable routing for lifts, see attached image for 2 common types.
*]The weight of the extension, as well as any friction in the system will be placed upon the motor as load. This load will also be placed upon the chain. Can it handle this load?
*]If the extension “jams” then the full stall-torque of the motor will be run through the chain. Can it handle this load?
*]Vex Linear Slides work best if left “a little loose”. If you use 2 of them together in parallel, and they are very rigidly placed, there is a chance that they will jam if they are not perfectly in allignment.[/LIST]These are just a few thoughts which popped into my head. I have every confidence that you will be able to accomplish your goal. My experience with the Vex system tells me that this design will be successful for you.
Another thought.
Have you considered using a rack-and-pinion setup along with the Vex linear slides? This provides a much more robust system, though the travel is limited. (You could use a rack-pinion system for the lowest stage, which drives a “cascade style lift” for the upper stages, in a multiple stage elevator. Refer to the attached image.)
Good Luck,
John