reverse forbar lift help!

VEX V5 Technical Support
1

So my teams robot is a reverse forebar lift with four motors on the lift, however whenever we move the arm down the arm tilts to one side can someone help?

2

Use c-channels to make it so the sides have to up and down at the same rate

3

huh? what do you mean we are using c-channels

4

C channels connecting the two lift sides.

5

Be sure to do some bracing in an x-shape for less screw joint looseness.

6

Make sure to use aluminum, it helps to reduce weight and stress on your motors,

7

And use rubber bands in a triangle.

8

Make sure to use VEX rubber bands or a heavy-duty brand. They last longer.

9

To ditto & expand upon the comments above:

  • in each segment of your lift you need cross-bracing. Just bracing once in one segment isn’t going to do it.
  • on our lift, my team has 1 or 2 c-channels spanning the gap (in different areas) as well as 1x pieces that cross in an X shape, attaching left side to right side. The 1x pieces are great because they’re lightweight and flat, and are still effective.
  • my team also has “self”-bracing on each vertical segment (from chassis to first gear; from 2nd gear to top gear), so that we have teeny 1x “X” bracing between the 2 c-channels comprising each side of the lift. Example: there are 2 c-channels going up from the chassis on the left side of the robot, with the gear sandwiched in between them. Where we can fit it, we have little 1x "X"s connecting these c-channels.
  • rubber band triangle won’t help your lift go up straight, but it will help your lift go up, period. The concept is that the triangle method provides continuous tension through the whole range of motion of the lift, not more when it’s folded & less in the middle. My team had to add a little appendage to one of the c-channels for the top point of the triangle; you’ll just have to play around with this to find a setup that gives you “neutral buoyancy” – the lift stays wherever you put it, without motor help.
2 Likes
10

You could try using anti slip matt so the lift cannot slip to the side.

11

What?

12

obviously we have a new goat of building

13

NEW META!! Guys anti slip mat will keep your lift from going to one side! I’m so surprised no one else thought of this, and I wonder why I’ve never seen it used like this before :thinking face:

14

How would you do that? Because our lift is bending and we have a match in about 20 minutes or so.

15

That was scarcasm
If you only have 20 min, add rubber bands to the side that tilts down and/or remove bands from the side that tilts up.

16

Yeah, we’ve been doing that. For a good 30 minutes.

17