pic: Shooter damaged a Boulder

[Type]

We are running 4" stealth wheels that are connected 1:1 onto mini cims. The only time we damaged the ball was when we were testing, and somebody forgot to reverse the left motor. This made both motors spin the same direction. It made two small gashes in the ball but it's still usable. We have another ball we bought, but we don't want to use it until we get the final version of our shooter made. Has anybody noticed a difference in performance in a wheeled shooter from a new ball compared to an old vall? And does anybody know how often they will switch balls out in the game?

[Ether]

Originally Posted by Type

We are running 4" stealth wheels that are connected 1:1 onto mini cims

What speed are you running it at?

[Type]

Originally Posted by Ether

What speed are you running it at?

To be honest, I don't really know. We have all of our electrical on a practice robot so we just plugged the motors into an old power distributor, with no motor controllers. It shoots more than far enough, just need the correct angle.

[Ether]

Originally Posted by Type

To be honest, I don't really know. We have all of our electrical on a practice robot so we just plugged the motors into an old power distributor, with no motor controllers. It shoots more than far enough, just need the correct angle.

The correct angle when you are running it straight off a fully-charged battery may not be the correct angle toward the end of an actual match when your battery is getting tired.

That's why it's important to test your prototype to see how much the correct angle is affected by voltage. If the effect is enough to be a concern, you will want to design your shooter to operate at a lower voltage (say 9 volts) and then used a closed-loop controller (PID, bang-bang, Take-Back-Half, etc) to hold the wheel speed constant as the battery gets weaker.

[Type]

Originally Posted by Ether

The correct angle when you are running it straight off a fully-charged battery may not be the correct angle toward the end of an actual match when your battery is getting tired.

That's why it's important to test your prototype to see how much the correct angle is affected by voltage. If the effect is enough to be a concern, you will want to design your shooter to operate at a lower voltage (say 9 volts) and then used a closed-loop controller (PID, bang-bang, Take-Back-Half, etc) to hold the wheel speed constant as the battery gets weaker.

We were planning on getting a gear box to run at 2:1 so we could decrease the speed of the motor but still shoot the same. The mini cims have no issues with shooting the ball through a 7" opening, the motors don't really even make a noise as the ball goes through. We just need to figure if we can afford to run all the motors we want on our robot (11 total).

[Ether]

Originally Posted by Type

We were planning on getting a gear box to run at 2:1 so we could decrease the speed of the motor but still shoot the same.

2:1 would reduce your wheel speed, not your motor speed.

Did you mean to say 1:2 ?

If so, you might want to instead consider increasing your wheel diameter by 50% and reducing your motor speed appropriately.

[Chak]

Originally Posted by Type

Has anybody noticed a difference in performance in a wheeled shooter from a new ball compared to an old ball?

We made a second iteration of our shooter that uses 4'' colsons and no longer rips up boulders. We're running that shooter off 2 775pros. We've noticed a significant and problematic difference between a fairly new boulder and the boulder pictured here, which is now even more torn up than before. I think that this is caused by the torn up boulder losing air faster and not "pushing back" as much on the shooter wheels. I guess catapults have the edge on this problem, although they might have their own problems.

[Type]

Originally Posted by Ether

2:1 would reduce your wheel speed, not your motor speed.

Did you mean to say 1:2 ?

If so, you might want to instead consider increasing your wheel diameter by 50% and reducing your motor speed appropriately.

Yes, that is what I meant. So every 1 rotation of the motor, the wheel rotates twice. But it appears you understood what I was trying to say atleast. Thank you for correcting me.

[Ether]

Originally Posted by Type

Yes, that is what I meant.

You might want to ask around for opinions from other teams who have tried that, before investing too much time in it. Just a thought.

[taytaythedj]

I also had made a prototype that resulted in this. I used a 4 inch hi-grip wheel. Only shot it about 10 times and it is covered in bruises. We named the ball Ricardo, so out little Ricardo was in a little bit of pain.

[Ginger Power]

Originally Posted by taytaythedj

I also had made a prototype that resulted in this. I used a 4 inch hi-grip wheel. Only shot it about 10 times and it is covered in bruises. We named the ball Ricardo, so out little Ricardo was in a little bit of pain.

What kind of compression, gear ratio, etc. did you have for your shooter?