Elastic Lifting?

Before summer came for my team and we were disbanded for school, I made a little prototype of an elastic lift. The advantage is that it doesn’t use any motors to get a high hang. The idea centralizes around a tower of elastics that you “wind up” before the match. Then this tower unfolds (to fit within the 18"*18") and at the end of the match, the bot drives towards the pole and a passive activation method activates, collapsing the tower and dragging the bot off of the floor. A c-channel lock could be installed so the bot could stay at the maximum height. I haven’t fleshed this idea out much so if it’s hard to understand, I’ve attached a (crude and not to scale) drawing.
So what do you guys think? Feasible if some more thought was put into it?

I think it is worth a test because the motors it saves and the limited complexity.

The big question is how to get motion both up and down. Basically, if you have elastics to bring the bar up, but then other elastics to bring the bar back down, they’ll just cancel each other out.

A rotational motion might be easier to accomplish. If you have a hook that stays at 18" and then rotates the entire robot upwards, that would be a one-way motion that could be done with elastics and a release.

I’ve mentored two teams that have built mechanisms that used a LOT of stored energy to complete a task that only happens once per match. It’s a good idea, but you will want to make sure that the structure is really strong, and that anyone testing or using such mechanism is using the right safety gear. I would even consider a full face shield and not just safety glasses during testing, as these mechanisms can be very powerful and dangerous.

There were quite a few stored energy lifts in Nothing But Net, quite a few teams had lifting mechanisms with platforms that would flip out of their 18" by 18" square, and use the stored energy to raise the lift. Not exactly the same concept, but the process of lifting could be slightly similar.

We had a lifting mechanism in NBN that used stored energy, and one thing that I also wanted to point out is that a strong locking mechanism would be needed, with so much stored energy the mechanism may want to release prematurely, which can cause problems during the match, and possibly harm people working on the robot. Otherwise, the idea sounds like it is very feasible, and has potential if it can work!

@Team9807B So what do you recommend for a strong locking mechanism? Something that can resist the force of like 10-20 rubber bands but can easily be triggered with minimal friction, using a passive system like shown above or pneumatics. Obviously, a pin and hole lock would not be ideal.

Would c-channels bend under that force?

Steel C channels don’t bend under that force. I haven’t experimented with aluminum ones. Where are you going with this?

Not going anywhere really… just brainstorming ideas.
Would standoffs be strong enough too.

Standoffs don’t bend under the stress of 14 high strength rubber bands, they don’t try to bend the aluminium C channel they are connected to either. (The C channel doesn’t bend under the force of 14 32" rubber bands at full stretch.) Unfortunately high strength gears do rotate around their high strength axles at that point. I definitely would recommend wearing goggles with this much stored energy as a screw came off and hit the ceiling with some force when I was prototyping.

Do you mean hs gears don’t rotate around their hs axles?
I’m not planning on using rubber bands, I made a dumbbell lifter with latex tubing, and it could lift up to 25 pounds.

No, I meant the inside of the gear stripped, so the gear could freely rotate around the HS axle.
Latex tubing is what I will be using as well, as the rubber bands keep stretching and breaking. Although poor quality rubber bands are good for testing sometimes.

There is a classic VEX video of one of the larger mentors standing on a length of C channel. It’s lot stronger than you think it is.

Can I see the video? And which type was it?
My catapult was able to bend steel c channels easily (Didn’t know I had to use rope/anti-slip mats).

I dug around for it but wasn’t able to find it. It was from around 2008 when VEX split off from FIRST (and started the huge growth we are seeing).