My team is looking at using the same cascading elevator for cubes and climbing with a shifting gearbox. We are looking at using 2x1 (3/16th wall) and the 2 inch linear roller kit from Competition Robot Parts or 8020 extrusion and rollers. Have any teams used these systems and have any advice on using one other the other? Any issues with jamming from lateral movement?
Thanks in advance.
Many of the Robot in 3 Days teams have been using the Rev Robotics elevator kit which uses 8020. Most of them have seemed to have good luck with it.
Just for clairty, the REV Robotics elevator kit uses the REV Robotics 1 inch extrusion. http://www.revrobotics.com/rev-21-1000/ (8020 is a different, but similar product)
OP said he plans on climbing with this elevator. 8020 is not suitable for that and it deflects ALOT. Play around with this calculator for a couple minutes and you can quickly see, even a reasonable sized length (80") will deflect almost an inch with <50lbs, easily achievable in an FRC match:
https://8020.net/deflection-calculator
3/16 seems kinda thick for boxtube, especially an elevator that will be large to climb. If its your only mechanism and you dont plan on adding a ramp mid season it should be fine, but it will be really heavy. Maybe use 3/16 for the bottoms struts and 1/8 on the ones that go up top to reduce the amount of weight up high.
Wow that is some thick and heavy tube.
Would 3/16 be justified if another robot was climbing on us after we had climbed? Or some combination of the stages, like just the 1st stage rails?
I’d be willing to bet something else is going to break before 1/8" boxtube fails on an elevator. Ofcourse its always better to be safe than sorry, so if you have the weight to use it, go for it. Just remember theres always a tradeoff.
This is not a valid calculator for a lift as the loading conditions are completely different. This calculator assumes a beam is horizontally loaded and fixed at one end (normal bending calculation). In the situation of FRC robots climbing you are actually more interested in the tensile strength of the materials (which is going to be way way way above the 150lbs of a robot).
It is actually likely that you will get some bending loading due to different robot setups which introduce a bending moment of the system, but even then you shouldn’t worry too much about the material failing as the failures will most likely be due to the assembly of the robot itself failing.
Its important when using calculators online that you make sure that the assumptions and setups match your conditions or situation or you are just wasting time.