Scissors lift gear ratios

VEX V5 General Discussion General Forum
#1

I’m new to building scissor lifts, and I’ve seen talk about different gear ratios.
I have 2 questions:

  1. What type of ratio is the best if I have 4 stages and want to get 2 cubes and a skyrise?
  2. What is the gear ratio of the purple Chinese robot is this video: https://www.youtube.com/watch?v=-BFRcLRlp1A

If possible, I would like a cad render or a close up picture on how to do a 1:15 gear ratio and a 1:21.

Thanks.

#2

I recommend 1:15 minumum for a 4 stage lift. 1:21 if your lift is heavy or you want more capacity.

Try to keep the gears as close together as possible to prevent twisting shafts. Remember that one motor’s torque cannot twist a shaft, but 2 motors geared down three times create shaft spirals with ease. Try to make sure that none of your shafts are transducing torque that might twist themselves.

There are a lot of things one should know when building a scissor lift in vex, and I am glad that this year’s game is teaching the entire community how to easily and efficiently build the dream lift in VEX.

#3

4 stages, and 2 cubes
Option1
-6 motor torque gearing, 1:7 gear ratio
Option 2
-4 motor high speed gearing, 1:15 gear ratio

“purple Chinese robot is this video” :stuck_out_tongue:
The gear ratio is 1:21 I think, it’s hard to tell.
Someone maybe correct me on this?

#4

Thanks to both of you, but I have another question.

Do you know how they mounted the motors on the scissor lifts?

#5

I’ve always just put it on the C-Channel, but make sure that both sides of the axle are supported. So you will want some sort of smaller piece of metal and/or standoffs to support the axle on the other side of the gear.

#6

No what I mean is how to mount the second motor on one side of the scissor lift. I’m know how to mount the first motor to the 1:15 gearing that I’m planning to do ( thanks Stanley ), but I’m confused on how I should mount the second motor to the gearing.

Thanks

#7

Oh, sorry about that!

There are two options. The first is that you have one motor on the first stage, and the second motor on the 2nd or 3rd stage. I like this method, because this will help reduce the amount of “slack” that builds up through the stages.

As you want to do 1:15, I suppose you are doing a 12t gear driving a 36t, and then a 12t driving a 60t. Whatever you are doing, I’ll use that as the example. So you can have one motor with its set of gears on one side of the 60t gear, and the other motor with its set of gears on the other sides. Essentially you have both motors and their gears rotating around the same 60t gear in the middle.

#8

Thanks 3921, kevin, and stanley!

#9

It can be done with two motors geared for speed on linear tracks too. Not as fast getting tall, but once there it is wickedly tall.

But for what you’re talking about, look at 929W’s reveal and get close up to see theirs. they were good last year but appear even better this year. I thought their autonomous that placed a beach ball on the tube was cool last year. That’s Hereford Zone Robotics of Maryland…

#10