Tray lift expanding help

So our team is trying to build a tray lift, and we can’t figure out how to get it to fold on itself. I saw the 448X goofy documentary, but that didn’t really help. We crossbanded our rubber bands, so maybe that’s why? Any suggestions on how to proceed?File_001 IMG_2450

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Pictures would help a lot in this case. Do you have any?

do u mean open your tray stages??

I edited the OG post, hopefully that helps?

Yeah, like the 448X robot. It won’t fold down properly.

put more stress on it
double up your bands
same # of bands twise the power

Yeah, we did that, but it doesn’t fold down. It’s fine coming up, it won’t fold down.

You guys are saying it need more rubber bands, but the person is saying it can’t fold down. Try to lower the amount of rubber bands and see if that works.

Does the build look okay? Do we need to space it differently or something?

As far as I can tell the build is okay, but I’m not sure on the cross banding. My guess is just too much rubber bands, so try to use less on the tray.

What kind of hinge do you use for folding your tray?

My team does not use a tray, but screw joints are widely accepted as best for this. What hinge do you use? I can’t tell from the photo.

Oh we need a hinge? What does that look like?

That’s maybe why it’s not working properly…

Like what mechanism lets it fold down?

It’s a passive one, the rubber bands are the things holding it together.

Is that what you mean?

Im not sure what you mean by a passive hinge. Do you mean there is literally nothing else connecting the stages?

Yeah…
That’s probably why, isn’t it? What do you use to attach it?

Most teams use a screw joint. There are some threads debating the pros and cons, but here’s what a screw join is. Its basically a screw screwed on the a locknut that is not tight enough to hold the joint in place, but loose enough to allow the join to move.

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