Catapult skipping

VEX V5 General Discussion General Forum
1

Hi,

We’ve just built a two ball catapult and are having trouble pulling it all the way down while using the motors (the gears start slipping about a third of the way down). We are using two v5 torque motors and have it geared 3:25 (1:5 and then 3:5 with the slipped gears being on the 3). When we pull the catapult down manually the amount of slipping on the gears is correct but it does not get that far down when it is pulled down using the motors. When we tuned the catapult prior to adding the slip gear and the motors, we used 7 rubber bands per side for 14 total rubber bands. We have a relatively long arm at 25 holes long. We are using staples #64 rubber bands and have them so that when the catapult is all they way up there is just a little bit of tension left in the rubber bands.

Any and all help/ suggestions are appreciated.
Thank you

2

I assume the slipping isn’t where it’s supposed to slip. I had the same issue a while back. You may have to change the placement of your rubber bands to closer together, then add a couple more. Problem is most likely that the force is too much for the motors to hold.

Pictures would help to make sure it’s not a build quality issue wherein the gears that are skipping aren’t properly supported.

3

I realize the gear isn’t actually turning the skipped gear in the picture. How does changing the placement of the rubber bands help?

image0-1.jpg
image0-1.jpg3024×4032 2.4 MB

4

It changes the launch/pullback power. In my informal testing, I found that using more rubber bands over a shorter space was easier to pull back with negatable firing differences.