Double Catapult Tuning Problems

Hi guys

So, double catapults. Ours is being dumb. We had it working correctly three days ago at the end of a competition. Now, the problem we’re having is that our catapult has mysteriously stopped hitting the middle flag. One ball still hits the high flag, but the other sails between the middle and low flags, sometimes toggling the low. Does anyone have suggestions on what might be causing this change, or how we could fix it?

Its very likely that a c-channel or something of the sorts has been bent on your catapult. Id suggest checking whatever stops the catapult arm when firing first.

We checked that, nothing is bent.

Have you tried replacing the rubber bands?

We’re using latex tubing instead of rubber bands, because their stretch lasts longer. We tried replacing them, no luck.

Did you change anything on your robot that would change the height of the catapult? Also, take a slow motion video of the catapult shooting two balls at once and look at it to make sure they are both leaving the catapult properly. One thing our team noticed is that if the balls were not completely settled in the catapult before firing, it messed up the shot completely. If you could post a picture we may be able to help you better.

Also another thing, is the robot shooting from the same spot every single time?

Yes, we are shooting from the same spot. We took a slow motion video, and while the top ball goes straight for the high flag and hits, the low never reaches the height of the middle flag. We are making sure the balls are settled before firing, and we haven’t changed anything since it was last working.

Double check support structures and make sure nothing got loose and moved a tiny bit? We had a sudden arm alignment issue and it turned out a support had moved a tiny, visually unnoticeable amount. It wasn’t wiggly loose but just off enough to cause an issue.

Verify no misc screws or nuts loose or randomly added? Check any shafts for twisting?

Weird that the top works fine!

We had this same problem when the standoff that sat behind the ball was slightly out of place, which messed up the shot by a couple inches. Make sure the backplate that the ball is against is tight where you want it to be.

Update: I forgot that I had a slow-mo video of the launch that would be helpful

Update: We fixed it. Despite the fact that we’re not sure why it broke in the first place, we fixed it by replacing the slip gear with one that pulls back further.

catapults are really finicky, any minor change will completely render your shot angles wrong.