Right angle 4:1 gearbox options?

Technical Technical Discussion
1

We’re looking to save some room on a mechanum drive by rotating the motors 90 degrees to the wheels. AndyMark has this 2:1 right angle gearbox, but we would need something more like 4:1. This could be done by adding a 2:1 spur gear, belts, or something else. It would be easier if there was a similar gearbox with a 4:1 reduction. Any options out there?

2

Take a look at what Killer Bee’s did a few year ago

3

In 2015, 1983 Skunk Works did something similar. We used the AndyMark LJ Bevel Box and then did did a chain reduction direct to the wheels. I think we did a 4:1 chain reduction to 6" Mecanums, 16T to 48T that year.

Here’s the best picture I could find: https://photos.app.goo.gl/NoSLbktucpLuwNuD2

The only COTS bevel gear sets I know of on the market for FRC (e.g. comes in a 1/2" or 3/8" hex bore or 8mm shaft mounting) is the 2:1 pair that AndyMark sells, the 20T 1:1 sets from AndyMark, or the 15T ones from Vex.

Without a COTS 4:1 bevel set option, if you’re not interested in broaching your own bevel gear sets, you’re probably best off doing an additional reduction off of the bevel box in gears/belts/chain.

4

While it’s somewhat of a more expensive option you could use a4:1 CIM sportinto our new 1:1 bevel box with 57 Sport Mounting Kit (am-3840_Sport).

5

That’s pretty creative, I like it haha. I’m wondering how well those will hold up over a season on the drivetrain though. Being mechanum it might be okay since they won’t see a huge amount of torque (compared to say, high-traction tank drive)

6

Yeah, that’s pretty close to what we’re looking at! Keeping the frame open like in the photo.

7

Oh boy that is a pricey option…but it looks really nice too. I’ll have to consult the students and see what they’ve come up with.

8

Just throwing more ideas out there, has anyone used an angle grinder gearbox in their robot before?

This guy is saying the Harbor Freight 9" grinder is a ~4:1 reduction:
http://www.etotheipiplusone.net/?p=3128

9

Attach to a VersaPlanetary 4:1, problem solved. Well, other than using a CIM or similar through a VersaPlanetary.

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