Large Reduction Single Speed Gearbox

[techhelpbb]

Originally Posted by Anupam Goli

If you can't find a COTS gearbox, try adding another stage of reduction in the sprocketing.

QFT most of the AndyMark Toughboxes are 12.75:1 stock.
2:1 can be obtained and that's more than you ask for.

[InspectorGadget1073]

Our team is only using 6 inch wheels. Please help us all.

[ASD20]

Now that I think about it, it is kind of interesting that Andymark is selling a kit where the slowest possible configuration is 14 fps and not warning people. I can see there being a lot of surprised rookies who cannot control their robot.

[Kevin Sevcik]

Originally Posted by ASD20

Now that I think about it, it is kind of interesting that Andymark is selling a kit where the slowest possible configuration is 14 fps and not warning people. I can see there being a lot of surprised rookies who cannot control their robot.

Oh, you don't remember the 2011 kitbot that was geared out of the box for 18 fps? Man those were the days...

[techhelpbb]

Originally Posted by InspectorGadget1073

Our team is only using 6 inch wheels. Please help us all.

What sort of help do you need?

Are you trying to target a certain number of feet per second?
or
Are you trying to target a certain ratio?

Resources on ChiefDelphi that can help you:
JVN:
http://www.chiefdelphi.com/media/papers/2059
Thad house:
http://www.chiefdelphi.com/media/papers/2681
Chris L:
http://www.chiefdelphi.com/media/papers/2165

As pointed out before if you can't get a ratio high enough from an existing gear box use that gear box to drive a belt or chain sprocket and then select those pulleys/sprockets to multiply the ratio.

For example: If a AndyMark ToughBox has a default ratio of 12.75:1 and drives a double 1/2" bore #35 sprocket with 12 teeth. Then drive the wheels with a 24 tooth sprocket (which happens to even fit a 4" AndyMark wheel) you have an additional 2:1 so that's total a 25.5:1 gear ratio at the wheel hubs. If you used the 15 tooth double #35 sprocket that chain will be a ratio of 1.6:1 so total that's 20.4 at the wheel hubs. If you play around with alternate gears within the ToughBox you can take that further. It's easy to get an additional 3:1 in just sprockets and chain using a 12 tooth #35 to a 36 tooth #35 sprocket especially if your tires are larger than 4" to add clearance for the chains (so with 12.75:1 and 3:1 that would be a total ratio at the wheel hubs of 38.25:1 and that's not even the maximum).

Make sure to consider the losses in the system that's why I linked the various common calculators.

I see AndyMark clearanced out all the StackerBoxes. I bought a bunch. They can feed into each other to multiply over and over the gear ratio just by assembly. Too bad they had 3/8" shafts. Each StackerBox had a 14 tooth and 50 tooth gear stock. So you could easily stack 3 and get a ratio over 45:1.