Kitbot on Steroids 2.0

[marshall]

Conversation just happened with some students on my team and it got me thinking...

Some years ago, 1114 posted an excellent resource for many teams to help them turn the kitbot chassis into something far superior. So in the spirit of the Simbotics Kitbot on Steroids project, I'd like to propose an updated version of the project or at least pulling some suggestions together for struggling teams.

The kitbot has come a long way since then but it's still not the best it can be for every game so what minor alterations can you make to the kitbot this year to make it more effective in competition?

Right off, I think replacing the kitbot wheels with wheels that can take rough top blue nitrile tread turns the basic kitbot into a much more defensively capable robot. What other suggestions can folks come up with?

[ThaddeusMaximus]

Mounting. The new AM14Us are getting better about this but interfacing to things with them is still not as elegant as VEXpro stuff

[Billfred]

Originally Posted by ThaddeusMaximus

Mounting. The new AM14Us are getting better about this but interfacing to things with them is still not as elegant as VEXpro stuff

As (probably) the first AndyMark employee to reach this thread, I'd love to know what things you're having trouble interfacing. (No promises we'll fix it to your satisfaction, but we can't fight what we can't see.) If you don't want to say it here, PMs or an email to (my CD username)@andymark.com will get it on the radar.

I'll put out what Iron Kings are doing, with the preface that we're sponsored by AndyMark and 20 minutes from the warehouse. Your team may arrive at different conclusions.

4" black HiGrip wheels. 4" because they are cheaper and we wanted the inch above the chassis, black from testing other engineers (hi Danny...) have done on how the different compounds handle. We'll probably have to change out wheels once a day depending on final weight and how we drive it, but we have measures to be ready for that. This is a little advanced for a Kitbot on Steroids document, but we expect it to work well.
5.95:1 gearing. That puts us around 15 feet per second, which is up significantly from the stock 10. With the wide open field and expected sprints for gears, we knew we wanted top-end speed. If we somehow end up heavier than expected, we may walk this one back a little.
Cut the front end plate, add structure back. We're doing fuel, and we're not quite to the point of over-the-bumper intakes. We may use the COTS cross plate, not sure how some other things will shake out.
Plywood bellypan. With a good coat of paint, of course.

[Jon Stratis]

With this game, perhaps the most important change many teams will do to the kitbot is open up the front to allow easier intake of fuel or gears. Figuring out an effective and easy way to appropriate brace the frame for such an intake is key to a successful design. Especially when you consider the number of mecanum conversion kits that appear to have been ordered from AndyMark, bracing the frame to keep it square and keep weight balanced is going to be key.

[Chris is me]

Change the gears out for Vex gears, put a plywood belly pan in and you're pretty much set, honestly.

I like switching to 4" wheels when possible to lower CG.

[Tom Line]

Vex Pro wheels with the versakey pattern, and vex pro sprockets. The vex pro wheels are far stronger than the comparable plaction wheels, and the versakey pattern addresses a long standing issue with bolts shearing off under high load when they are subjected to sprocket shear.

Other than that, the new kitbot frames are pretty good for a new team.

[mastachyra]

Originally Posted by Chris is me

Change the gears out for Vex gears, put a plywood belly pan in and you're pretty much set, honestly.

I like switching to 4" wheels when possible to lower CG.

Why switch to aluminum Vex gears over steel AndyMark? I see Vex now has steel gears, but not in the sizes that might fit the Toughbox.

Just curious, have you seen this done? I assume the Vex gears wold have to machined down to 0.400" thickness to fit. Or maybe you meant replacing the whole gearbox.

Thanks

[marshall]

Originally Posted by mastachyra

Why switch to aluminum Vex gears over steel AndyMark? I see Vex now has steel gears, but not in the sizes that might fit the Toughbox.

Just curious, have you seen this done? I assume the Vex gears wold have to machined down to 0.400" thickness to fit. Or maybe you meant replacing the whole gearbox.

Thanks

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.

[Tom Line]

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.

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.

[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?

[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).

[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).

[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.

[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.

[wilsonmw04]

Originally Posted by Jon Stratis

With this game, perhaps the most important change many teams will do to the kitbot is open up the front to allow easier intake of fuel or gears. Figuring out an effective and easy way to appropriate brace the frame for such an intake is key to a successful design. Especially when you consider the number of mecanum conversion kits that appear to have been ordered from AndyMark, bracing the frame to keep it square and keep weight balanced is going to be key.

You mean this?

http://www.andymark.com/AM14U3-p/am-14u3-fro.htm