Prototype Small Wheeled Shooter

We just posted a blog entry about our current prototype shooter. It uses much smaller diameter wheels than many teams that we have seen post of CD. We’re hoping this idea might inspire some teams that are struggling to package their large shooters.

Blog Entry with full specs on the shooter configuration.

Good shooter!! what motors do you have?

The blog entry has the full specs for the prototype. The two motors are a BB550 and a BAG motor.

Well…this is kinda awesome.

Try slowing that second motor down (the BAG motor) . Try running it at ~10 volts.

See what happens. Easy enough to do.

So you’re actually spinning the 2nd wheel slower than the 1st. What made you decide to do that? Seems everyone is making the 2nd wheel spin faster than the 1st.

Read the blog again. He is spinning the 2nd wheel FASTER than the 1st.

1st wheel 550 geared 10:1 = 1,930 free rpm

2nd wheel BAG geared 1:1 = 14,000 free rpm

You are correct, I read the 14000 on the chart provided by FIRST as 1400.

I withdraw my question.


This is great work! I admire your lack of hesitation to give away this information. Shows you and your team’s true colors.

Thanks and good luck at making it even better!


P.S. - Have you tried shooting from the floor? What kind of angle do you expect to have to pitch the shooter to for the 3pter?

Just wondering how you set the one gearbox to be a 1:1 ratio?

Also, anyone have any ideas as to how you mount the banebots wheels directly to a CIM?


On their blog they explained that they used a Versaplanetary box with all of the gears within removed. The output shaft of the VP boxes are the same hex as the banebots wheels.

Thanks, didn’t see that there.

Also we were wondering how you direct drive the banebots wheels with a CIM.

The reason they are using the versa may be because the output shaft on a versa is actually a .5 hex, which is an ID that banebots sells their wheels with.

Locking a stage in a planetary gear is fairly simple - look up how people did it with globe motors. It involves glueing the sun gear and planetaries together with something, then dremeling off the teeth of the planetaries so they don’t touch the ring gear.

FYI, you can’t really be guaranteed that you can direct drive a banebots with a cim without installing an insert and broaching it with a keyway. The unfinished bores on the banebots wheels are not actually a measured diameter: it varies. They ream it to .375, but in most cases it comes bigger than the 8mm shaft of a cim from their manufacturer, and hence will not work directly on a cim.

8mm 500 Hex Adapter Shaft (am-0588)

We hope so.

Thanks for the recommendation; we still have a lot of work to do to optimize the whole setup. With the versplanetaries we can swap around motors and gear combinations so quickly that we plan to test a large number of them. We’re also going to try to standardize on voltage as well, but that will take a bit more programming (since we don’t have any type of speed feedback we can’t do Bang Bang yet). We’ll take your advice and test it. We agree that the last wheel is spinning too fast and is most likely slipping.

Thanks for the compliments. That really depends on how high we end up shooting from and our distance away from the goal. I’m not sure we could give a number. That height was less than 5 feet so in theory we could just shoot from there.

We took the ring gear, sun, and planets out of a 10:1 versaplanetary. I’m not sure if you can do the same with the other gearboxes. Paul Copioli can probably expand on that. If I remember I’ll post pictures in tonight’s blog update. We’ll probably have to swap around a few of the gear ratios during testing anyway.

My thought would be to get an AM 8mm Hub and drill out the Banebots wheels for that and bolt them to it. I think it would work better than the 8mm to 1/2 hex adapter (It’s not very long).

It’s much easier than that. The spline on the output shaft is the same as the one on the sun gear. You just remove the whole 10:1 stage and bolt the front and back of the gearbox together.

The three 0.4" wheels fit perfectly. The two .8" wheels have about .5" sticking over the top of the shaft, we just put a longer 1/4-20 bolt on with a washer, seems to work well enough.

Why did you go with 2 different wheel thickness? Just what you had around?

The .4" orange wheels can be bought using the BB PDV. We purchased 2 .8" of all three colors after we tested how grippy they were to the discs. We just left the .4" ones on there for now. We’ll best testing a bunch of different wheel combinations over the next week.