My robot lifts two pins simultaneously, but the top pin slips a little / sometimes falls during the 180° rotation of the mechanism. This issue may be related to the placement or force applied by the pneumatic components.
Try with one pin on each side
Can you upload a few images of your mechanism?
Without seeing exactly what you’re dealing with, little can advice can be given besides generic things like “Put a piece that prevents slippage.”
I ment like for like strategy of double stacks at a time but try adding the short pumper things
The issue can be either
- Force(aka your pneumatic cylinders aren’t applying enough pressure): if this is the problem, you should probably check your pneumatics for leaks and stuff.
- Grip: if this is your problem, add rubber bands(because rubber bands are always the answer to grip problems) to the claw, and the thing separating the two pin stacks.
I don’t know exactly if these are your problems, but like what @Some_random_person said a picture would help.
Had this problem too our problem wasn’t that our grub wasn’t working it was that our claw was too small to hold 2 if that is the case it is an easy fix you can just use a slightly taller plate to grab the pins
Maybe your claw isn’t tall enough to get a good grip on 2 pins. I’m just assuming you mean you have a 2 stack in each claw.
My bot has that same issue, we made the claws extend higher, but sometimes one pin will get loose. To still get good points with little to no risk we just stack one pin on each hole of a beam and either put that on a stack or more preferably, on the standoff goal 
.
We then use the rest of the time making stacks.