The Thrifty Bot 2023 - 2024 Product Releases & Updates

I’m a little surprised that you didn’t use a similar technique for the double gear. I’m assuming the double gear is steel and it seems like you could have saved a bit of weight as well as a lot of machining time by making the central shaft out of aluminum and then fitting two steel gears on the two ends. Plus, for different gear ratios, the central shaft could have been a common part and only the steel gears would need to be different. It would also make it easier to replace one or both of the steel gears if there was some wear over time.

Did you look at the possibility of having a set screw inserted from the inside of the azimuth gear? I’m not sure the pockets are quite deep enough to give you enough room, but it looks like there are a couple of areas where you could have milled a through-hole or slot in the azimuth gear to give you the room to insert a set screw and have room for a tool to tighten it.

Having a positive mechanical locking feature like that would give me some piece of mind when it comes to students’ attention to detail when assembling these modules. Or do these parts come bonded together “from the factory”?

Pretty sure those are factory bonded…

On the cluster gear, splitting it into swappable gears would add quite a bit of risk and potentially volume for connections and retaining features. I agree that having swappable gears is a cool thing!

They would come pre bonded. Don’t want to have teams have to hassle with that.

For the double gear it’s easy enough to keep it pretty weight efficient, the azimuth gear in all steel would be very heavy, even when thinning things out to really thin. Basically the azimuth had the largest ROI for weight savings in the module so it made sense to give it a try, we have early test article modules from last November that are still in great shape and we purposely went out of our way to beat the crap out of them. We basically asked the kids to purposely try to break the swerve (120lb test robot, ramping off the charge station full speed, flipping the robot over several times, hitting walls full speed) we stopped testing as aggressively after breaking several NEOs :sweat_smile: and bending multiple frame pieces. I am definitely not concerned at all.

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Is the gear ratio for turning appropriate for a TTB Nova/Redux Nitro 775?

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Got a grease hole? No grease mess

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I’m not sure where you’d want a grease hole. I think if you want to grease, you could just take the top cover off with two bolts.

The azimuth is 25:1. My assumption is it would work with the redux motor just fine. (Assuming 9k RPMs motor)

I’m hard pressed to think of a better way to stress test anything.

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Why no 8mm keyed drive / kraken rotation? /j

I’m actually disappointed that the motor plates did not include holes for mounting either a Versaplanetary or a Ultraplanetary gearbox.

By my calculations, a NEO550 with either a VP lite (1 stage) or UP (1 stage) would be able to save about 0.25-0.30 lbs per module and would have similar speed and torque as a NEO.

I suppose that teams could create their own adaptor plates that could mount those gearboxes to the existing module design by having with a set of holes at the correct diameter for the gearbox and a second set of holes at the correct diameter of a full size NEO.

Thinking bigger picture, given the smaller overall diameter of a NEO550, it looks like there would be room to locate this smaller motor closer to the axis of the azimuth gear and reduce the overall size of the top plate to create a somewhat narrower module. It wouldn’t be as narrow as the SDS MK4n, but it it could definitely free up some space on the robot between the modules. Would you guys consider designing / offering a motor plate option that would adapt to one or both of these gearboxes in a slightly narrower configuration? Again, I suppose this is something that teams could design themselves. But having this option as COTS would be great for teams that don’t have the machining resources to make these plates themselves as well as allowing these plates to be used for multiple seasons.

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One thing I noticed with the onshape model that I wanted to bring to your attention is that the screws in the pinion assemblies create an error whenever I am trying to measure mass properties that results in being unable to measure anything including them.

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Once we get back from IRI I will take a look at what’s causing that, thanks for letting us know!

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