VEX West Coast Drive

Had an idea today to make a west coast drive out of vex parts, and here’s what I came up with. Recommendations are appreciated, since I have almost no experience designing things for vex(I lead mechanical on our schools FRC and FTC teams). It uses 2 turbo 393’s on 2.75" wheels, for a calculated speed of 2.9 ft/s.
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2.75" traction wheel is 2.75" , but I believe 2.75" omni-wheels are actually a little bit larger than 2.75". I know this is the case for 4" wheels, so I assume it is the case for smaller sizes. So based on that, this design wont work unless you increase the traction wheel’s diameter with rubber bands or something. Cool overall design though.

Also, why are you using the older motors?

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interesting take on powering a drive, in vex we usually just have the motors sitting on the inside of the chassis instead of op top of the sides since it involves less gearing.

if you want to pursue this type of layout, I’d recommend not cantilevering things. that’s where you don’t support an axle on both sides of a wheel or gear or sprocket. it puts a lot of stress on the axles and causes friction and bending, especially on something load bearing like a drive.

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Thanks for the info. Looking at the CAD, the omni wheels are only bigger by 0.15mm so they might not be an issue. If they are, using rubber bands with something to hold them onto the wheel seems like a good solution, so I’ll remember that.
I’m using the 393’s since that’s what my school engineering lab uses, at some point(maybe tonight) I’ll make a version that uses the newer V5 motors.

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I had noticed that, and wanted to take some ideas from my FRC experience and design with them.
The concept of WCD in itself(at least in FRC) implies cantilevered axles, so that’s why they’re here. I agree that it would reduce the friction and bending loads on the wheel axles, but that isn’t a problem that I’ve come across in FRC and FTC, so I’ll do some testing when we go back to school(soon tm). We ran cantilevered axles on Tetrix bronze bushings last year, and didn’t have failures in the axles or the bushings themselves. However, this would make sense as an issue in vex since the bearing blocks are plastic and the axles are smaller.

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yeah with stronger and more robust parts like in frc I would think cantilevering is just fine, but vex shafts and bearings can not take a lot of force when the shaft acts like a lever, and that’s what happens when you put the weight of a robot on a cantilevered drive.

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