What is the consensus regarding the amount of “squeeze” on the ball as it leaves a shooter (1 or 2 wheel configurations)?
It depends on the ball type. This year I’m thinking approx. 1.75"-2.25"
We found that about 2" works well, but it depends on what you’re trying to make the ball do and how you’re doing it.
From what I have seen, the average is about 2inches.
But the range is about .75 to 3-4 inches.
Prototyping will be the best way for you guys to figure out what works best for you.
Uhh isn’t .75 the same as 3/4?
I meant 3 to 4 inches. 
This is a LARGE range of performance! People skimming CD to get a number for their CAD model or block of wood prototype should take a look at these numbers and realize that they need to make an adjustable rig, or multiple setups of the shooter in order to make the robot work.
The main factors we have found that affect shooter variables:
- Surface ball is compressing against. This could be a wheel, a pair of wheels, or multiple wheels / roller. Some teams experiment with making their wheel concave.
- Tread material. Different materials deform in different ways, and ultimately a shooter that works using compression will have different dynamics with different materials on each side of the ball. We like our smooth sheet steel hood, and aluminium works just as well for our setup.
- Method of loading. Many teams are loading their shooters from underneath, modeling their robots off of the popular ground loaded turreted shooters from Lunacy and Aim High. Others may be building mechanisms that load with gravity. Results WILL vary!
When in doubt, do one last prototype…
Do a prototype. I’m on two teams right now (2079 and 619) and they both came to drastically different conclusions about the amount of squeeze, but both teams have functioning systems.
“-” != “/” :rolleyes:
The original post was edited to replace the / with -
Depends on the range you want to shoot. We’ve found that 1.5" is pretty good.
Depends on your shooter wheel tread.
In all of our prototypes, we’ve never had > 1". We’ve also never used skyway wheels.
working with our prototype last weekend, I found the smallest change in pressure at the right point really affected the behavior of the ball. Pushing on the lexan hood with my thumb at about 45 degrees angle was enough to go from the 2pt hoop to the 3pt hoop.
How long the ball stays compressed and in contact with the wheel and the contact with the hood as it is leaving the shooter also affects the angle of the shot.
Prototyping the shooter was certainly worth the effort we put into it.