Lift design

Hey guys we are currently building a lift and we are having trouble with having our lift expanding. Our lift currently only stays in one position and we can’t have it extend outwards. I will leave a pic of our lift down below and we would love your help

Not quite sure what you need help with, could you try to give us a little more information?

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The gear is attached to the top row of holes but the joint for the bar attached to the powered limb is attached to the center row of holes. That may not be the issue, but the picture doesn’t show much and that’s all that I can see that might be off.

Okay sorry for the lack of info the problem we are having is that the one bar doesn’t rotate independently. Basically we want the bar perpendicular to the ground to extend upwards and rotate independently so the lift can condense and expand I will send a video and I think that might help more

Does that make sense

I think you might want to build a 4 bar:

Or a chain bar:


I think what you are trying to achieve is a 4 bar linkage.

This is when you have beams creating a 4 sided shape, often a parallelogram, so that if you rotate one bar relative to the other (which is what you’re doing with your lift), the whole thing changes shape in a desirable way (in your case, moving upwards while keeping the end parallel to the ground)

this is a good video showing some of the basic concepts behind 4 bar (and other n-bar) linkages

it appears that you’re 3/4 of the way to having a proper 4 bar linkage, you’re just missing a top bar to keep the end of the lift parallel to the ground.

One problem I will note in your case is that it appears you are trying to drive the lift directly from the motor. The motor does not have the strength to do this, and it has far too much speed. You can trade that speed for more torque though, using a gear ratio.

I would recommend using a 1:7 ratio to drive your lift, which is the motor powering a 12t gear, which drives the 84t gear that the lift is attached to. What this effectively does is make it so for every one turn of the motor, the lift will only turn 1/7 as much. This will give the lift 7 times the strength as the motor, with only 1/7 of the speed.


I built the four bar from the Kepler electronic video and this what I got. We can’t attach the top bar because we would be out of the 181818

The point rotation is really loose and if I tighten it the bars won’t condense and extend

The joints are supposed to be loose. It’s anticipated to have some slop on your lift as nothing is perfect.

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