Kitbot on Steroids 2.0

[Lireal]

Originally Posted by Tom Line

We have seen significant wear on steel gears in a 6 cim drivetrain. We've seen aluminum gears wear out in 4 cim drivetrains. Unless you are desperate, or enjoy maintainance, the drive train is the last place your want to go for weight savings.

Where in 3 CIM gearboxes is the best place for steel gears? 3rd stage, pinions?

[Donut]

We've run modified kitbots the last two seasons and will again this year, they work great.

The biggest bang for your buck change is better optimizing wheel size and speed for the game and your strategy, the default wheels and gearing are serviceable but rarely what you would pick starting from scratch. This is just the nature of not knowing the game challenge ahead of time.

This year we are using 4" wheels leftover from 2015 (because we used 6" wheels bought on clearance from AM that year, for ground clearance over the bump and more speed). We are doing the same 5.95:1 gearing from AM Billfred mentioned since we are focused on quick cycling. No need for extra tread this year, if we are asked to play defense repeated ramming and manuevering would be more appropriate for our gearing.

Last year we ran 8" VexPro wheels on the kitbot, because the default ground clearance was inadequate and we wanted the traction for defenses. We 3d printed spacers with help from this post so we could use the belts and pulleys from the kit to drive the versakey pattern. Biggest problem we had is AM sold out of extended toughbox shafts quick, so we had to limit how far we could widen the wheel channels and somewhat bent our outer frame rails to ensure the output shaft was supported on the end.

Other items that would be helpful:
Encoders. I'll put a call for help on this one now, the kit toughboxes have holes for mounting an encoder on the output shaft on the motor side, but the E4P and E4T units we had lying around didn't thread into them easily with the provided screws. Do we need to drill out the holes sightly? Tap them? Get self tapping screws?
Bracing for openings in the frame. Last year we ran VexPro 2x1 tubing across the top of our frame and with two legs out to support the front frame rail at the opening we cut in it.
Better ways to go vertical from the chassis (mounting). We've used corner bumper brackets and oversized L brackets to do this recently. Gussets off the side of the chassis would be much more robust.
Proper bumper connections. T nuts are awful, there's nothing quite like discovering the only nut on one side of your bumper has backed out and fallen into the pool noodle abyss, and you have a match in 10 minutes.

For all recommendations, you want to keep things as low cost as possible and when you can allow teams to reuse items from past seasons they may not have used. We matched VexPro wheels to the kit pulleys and belts last year because we didn't have the money on a PO to get new pulleys from Vex on top of the wheels. Similarly we got clearance 6" kit wheels from AndyMark in 2015 because we couldn't afford plaction type wheels with all the parts we were getting for a superstructure. We're trying to use E4P encoders now because we already have them still in the bag. Items like ball shifters aren't worth the marginal benefits when the dollars could be better spent on a few Versaplanetaries or Banebots transmissions so that teams actually have functional manipulators. Better to change the gear ratio in the toughboxes instead (stealing from a past season's transmission if you can).

[pilleya]

Originally Posted by Lireal

Where in 3 CIM gearboxes is the best place for steel gears? 3rd stage, pinions?

Steel gears are best used to replace gears that have a small number of teeth and are under high load( ie in the final stage of reduction).

[waialua359]

Originally Posted by marshall

I'm hesitant to use aluminum gears with a 6-CIM drivetrain after what we saw last year. It just seems to be asking for the aluminum gears to strip. 4-CIM is probably fine.

Using Aluminum gears in our drivetrain cost us the Hawaii Regional last year. Never again.

[Donut]

Originally Posted by Donut

Encoders. I'll put a call for help on this one now, the kit toughboxes have holes for mounting an encoder on the output shaft on the motor side, but the E4P and E4T units we had lying around didn't thread into them easily with the provided screws. Do we need to drill out the holes sightly? Tap them? Get self tapping screws?

In case anyone finds this on a search in the future since I did not find anything about it in a CD search, we ended up getting these mounted by widening the holes with a 5/64 drill bit and then the screws that came with the E4P were able to thread into the plastic. All the instructions that I could find indicated the screws should have threaded in without modification, but I know the E4Ps were included in the kit years ago when the original toughboxes were used so maybe the holes were slightly different for those. All current instructions mentioned using a spacer tool for centering the encoder mount, and the old E4P units we have do not have that centering tool.