Drive Base Help

[IronicDeadBird]

[quote=redfancy;1585966]Minimal testing. Very very minimal. We never had a practice bot and our drive base wasn't ready pretty much until bag and tag.

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Yeah that was a killer this season we went with a tread design ran it over some defenses and were worried about it surviving the impacts so we switched to pneumatic wheels and a suspension system. Stress testing a robot is important cause the sooner you find points of failure the more time you have to iron those points out.

[troy_dietz]

Originally Posted by carpedav000

The 221 system does not have a center drop, but you can easily remedy that by using smaller wheels for the outside wheels

If you're using pneumatic tires, you can just inflate the center wheels slightly more than the outer wheels, or use a belt sander to take off some of the tread on the outer wheels. (or both) Not only will it create a drop center, you'll have less issues with turning scrub.

[BetaHelix]

Do you have access to a press brake? If so you could build something similar to our drive this year (pictures below). We used 8 8" wheels with 15mm belts and 4 toughbox micros at 12.57:1 (I think). We used 1/2in of drop on the centre wheels. The side plates are .090 5052 aluminium, laser cut, but could be handmade.

[asid61]

Originally Posted by Chris is me

16T #25 chain sprockets are probably too small for this year's game. They're quite undersized for the torque of 8" wheels and the shock loads of hitting defenses hard. Many, many teams have thrown chains with them this year. I would do 22T if you have the clearance, or even 12T 35 chain.

We ran 16t center-to-center outside of tube this year and didn't face any problems with the sprockets until SVR, when the chain wear and bearing blocks drifting made the chains super loose (and even then we only threw them once IIRC). If one is running chain in tube or something similar with the sliding versablocks and makes solid chains with the Dark Soul chain tool, I think 16t sprockets can work.
We ran 4 CIMs on 8" AM pneumatics.

[GCarnes]

My team used the KoP chassis with 6WD 8" Andymark Pneumatic tires. We ran the chassis in a wide bot configuration, 30" wide by 28" long. We decided these dimensions mainly by testing using the stock chassis axle holes and also through some CAD work. We also cut angles into the plates using a vertical band saw to give us a better approach angle. The main thing we learned through having a practice bot is that you need a lot of extra supports in the chassis. You can see yellow churros between the wheels that support the two side plates, as well as yellow 2" angle above the plates to support them. We ran long churros between the inner plates to support the bot width ways as well as a 1" square tube and the AM Cross Plate. We are running the KoP toughbox minis as our drivetrain gearboxes along with the KoP drive pulleys and belts. The bumpers are supported above the frame using the blue bumper brackets above the chassis. This bot held up very well all season long. Zero failures the entire season.

[messer5740]

Originally Posted by GeeTwo

AndyMark also sells optional upgrades for the for the AM14U2/3: a wedge plate to solve this issue, and a cross plate to help with an open front/rear. One wedge plate adds close to 3" of length to the chassis length without increasing the wheelbase, but it does help get over the category B and D defenses. I can't vouch for the cross plate.

They sold wedge plates?!?!?!

[Knufire]

Originally Posted by messer5740

They sold wedge plates?!?!?!

They came out later during build season.

[asid61]

Originally Posted by troy_dietz

If you're using pneumatic tires, you can just inflate the center wheels slightly more than the outer wheels, or use a belt sander to take off some of the tread on the outer wheels. (or both) Not only will it create a drop center, you'll have less issues with turning scrub.

Inflation alone does not work, from our experience this year. Sanding down the tires may help but in the end we ran a 3/8" center drop (although 1/4" was working ok). It would be hard to get enough drop without actively doing something to add it.

[messer5740]

I would be careful with using the angled plate of you plan to have an opening in the middle.

[Billfred]

Originally Posted by messer5740

They sold wedge plates?!?!?!

Posted on AndyMark's YouTube January 15th, after Kickoff (but in Week 1 of build season).

(scribbles notes on this for next year)

[messer5740]

Originally Posted by Billfred

Posted on AndyMark's YouTube January 15th, after Kickoff (but in Week 1 of build season).

(scribbles notes on this for next year)

Ah I always looked in the drive base category to look for upgrades. I didn't see the upgrades until AFTER our competitions were over.

[OccamzRazor]

Originally Posted by asid61

Inflation alone does not work, from our experience this year. Sanding down the tires may help but in the end we ran a 3/8" center drop (although 1/4" was working ok). It would be hard to get enough drop without actively doing something to add it.

The 3/8 drop works well with pneumatic wheels, you are right in that inflation barely does anything at all on these specific AM wheels. I saw a team next to us really struggling at Champs to get their robot to turn without brownout issues because they neglected to include the drop. I told them to try wrapping the center wheel with layers of duct tape and that actually fixed their issues aside from the duct tape appearance.