Hi, My team is trying to again to climb today we have two AM 2774 http://www.andymark.com/product-p/am-2774.htm and it is still not strong enough to climb. How are teams climbing!!!
Hi,
Team 5572 Rosbots is using a mini-cim on a versa planetary with a over reduction of 100:1
Two of those gearboxes seems like a strange and potentially broken way to do that. Does your system spin properly when it’s not lifting?
Also, how big a pulley are you using, and do you know what gear ratio you’re using?
Before you attempt climbing or testing a prototype for your climber you should first have a gear ratio that you know is sufficient to lift the weight of your robot. If you haven’t done the math behind your climber, I’d suggest that you take a look at the JVN Design Calculator, which is a useful tool that can help you with that (as well as many other applications).
Like many teams, we are using a winch style system which consists of a durable motor (like a miniCIM or a 775pro) driving through a planetary gearbox (like banebots or a versaplanetary).
Our team has calculated that it should be possible using a CIM and an Toughbox Mini - see below - at 12.75 to 1 gear ratio.
Our team went over kill and is using fhree mini-Cims in a 10.71:1 gearbox. We could get away with two but thought better safe than sorry!
If you need a working climber design, feel free to use ours.
We’re using a single CIM on a 12.75:1 TB-mini, and using 1/2" hex shaft covered with hooked fastener strips. It looks like the gearbox you linked only does a 4:1 reduction - that appears to be your main issue.
We are using a single CIM at 36:1 Versa Planetary gearbox. The roller is 1 1/4" in diameter.
2 sims attached to toughbox mini. 2 in diameter pipe that it spins with friction tape and a lasso
104:1 gear ratio my friend. Bane bots motor with an attachable planetary gear box>
we are using Vex Planetary 100:1 with a Vex 775 pro to a boat winch with 3:1 and a tapered drum with a min dia of 2" covered with hook velcro and we use a 1/2" a nylon rope
this is a few weeks old our new system picks up the rope faster
https://www.youtube.com/watch?v=9lm5PH-Qxqk
We are using a 50:1 versaplanetary with a bag motor. There’s also a 1 to 1 full sized 20dp gear set to protect the versaplanetary a little bit. We are using a ratcheting wrench to prevent back driving and for rope we are using 1" velcro stitched to webbing.
Feel free to pm me for help getting your climber working. If you let me know your meeting times I may even be able to come and help you guys in person.
I assume you guys have tested this? The math is not working out for me for lifting a robot.
How did you do the math without knowing the winch diameter?
how small would it have to be to lift 120lbs?
He didn’t specify a spool diameter, so you can’t do all of the math. Even so, a Bag motor with a 50:1 reduction and a 1" spool would be plenty to lift the robot. Here is the calculator that we are using this year: Link. If you save a copy of it for yourself, you can edit values.
Input values into the yellow cells, change the orange cells to match which motor you are using, and view the output in the blue cells.
EDIT: for the OP of the thread, can you post a picture of your climbing mechanism? It will make it much easier for us to help you.
I stand corrected although the listed stall torque is inconsistent with what is listed in the Vex site.
Looks like 842 is getting the stall torque here. Measurements instead of specs.
Thanks for pointing that out. Odd that Vexpro lists two different values.
http://motors.vex.com/ Gives a stall torque of 3.8 inch-pounds
http://www.vexrobotics.com/vexpro/motors-electronics/217-3351.html Gives a stall torque of 3.5 inch-pounds