How do you get a motor to have the perfect balance of speed and torque in FTC?

So our team has access to HD Hex motors with planetary and spur gearboxes, and our shooter design has two motors on either side to shoot the ring. However, we are having issues trying to get an operational shooter to shoot in the high goal. Even when testing with a drill at full speed, we can’t seem to get the ring to go farther than a few feet.

We also tested a 1:1 ratio adapting from an HD Hex motor to a VersaPlanetary Gearbox with a Colson Performa attached to it, but the wheel stopped as soon as it touched the ring, which means that we need more torque. Problem is, the wheel doesn’t seem like it would be fast enough to shoot if it was any slower.

How have your teams implemented shooters and how can we maximize ours to its best potential?

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How much compression are you using on your shooter? Also, which other wheels have you tried?

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this is probably a good place to start


We have tried REV 30mm Wheels and 90mm Grip Wheels. We decided to switch to a VEX system because we could have more control over the gear ratios we could choose in the space that we have.

As for compression, we have a fair amount, but I’m not sure how to give a specific number.

Measure the distance between the shooter wheel and the hood, or the distance between the two shooter wheels, then subtract that distance from the diameter of the rings (5in?) to get compression. Pictures or videos of your shooter would make helping you easier. It sounds to me like you may have too much compression but I cant say for sure without some numbers or pictures. Increasing the inertia of your wheel may also help.

I don’t know if you need that much control over the gear ratio on the shooter motor, from what I’ve seen most teams seem to be running 1:1 motors on their shooters in ftc

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Ok thanks, I’ll get back to you at our robotics meeting tonight.

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Do you know what wheels they are using?

Most seem to be like stealth wheels or something like that

Unless there is some source of friction in your system, you almost certainly too much compression. I have gotten a 90mm rev wheel to shoot the disks adequately using a 1:1 ratio, and <0.5" of compression. I believe I found that 0.25" worked the best for my prototype. That was for a 1 wheeled shooter, but I would imagine that compression would be pretty similar for a 2 wheeled one.

Most wheels should work fine, but remember that wheel diameter affects the linear speed of your shooter


Thanks so much! We ended up using a 0.25" compression with our Colson Performa wheels and are able to shoot a considerable distance now.

I don’t have any usable photos, but thanks a lot for suggesting that compression might be the issue. @Patrick1 said that a 0.25 inch compression would work and it did!

Here’s a gif of our shooter working though:


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