Drive Base Help

[redfancy]

Ok, to answer some questions:

We are planning on taking the new bot to an offseason event, probably Calgames. Our old bot ran a KoP 6WD with 8-inch pneumatics. We had major issues with our gearboxes, which happened to be the exact same 3-CIM ones suggested before. Since the only thing we could do was defense, our gearboxes took a lot of stress and it was enough to fracture and completely shred our aluminum gears. We were advised to just use 2-CIM systems in the future and also decent steel gears.
Also, we didn't secure our gearboxes very well, and that combined with the hole we had in the frame for intake resulted in the bot bowing inwards and twisting the wheels/axles out of alignment. The wheels were actually hitting the metal of the base. This was probably exacerbated by turning scrub, since all wheels were on the same level. So, we took the bot apart multiple times at competition, which was a pain with the KoP base.
We aren't trying to rebuild the same bot though-we're entirely redesigning.

Also, with 6 8-inch wheels, it was a really really tight fit. We had to trim down the bars perpendicular to the wheels so that they wouldn't hit the metal. Also, does the KoP base have pre-drilled holes that would let us drop wheels a good distance?

The AM2494 and 221's chassis seem simple and stable, but would we be able to drop wheels with them?

After reading through, we're leaning towards the VersaChassis. Also, using four Colsons and four pneumatics sounds good. When teams go over obstacles like the cheval and moat, they tend to fly over and then land. Is stress upon landing an issue with the Colsons?

Thanks so much for the help, everyone!

[carpedav000]

Originally Posted by redfancy

Ok, to answer some questions:

We are planning on taking the new bot to an offseason event, probably Calgames. Our old bot ran a KoP 6WD with 8-inch pneumatics. We had major issues with our gearboxes, which happened to be the exact same 3-CIM ones suggested before. Since the only thing we could do was defense, our gearboxes took a lot of stress and it was enough to fracture and completely shred our aluminum gears. We were advised to just use 2-CIM systems in the future and also decent steel gears.
Also, we didn't secure our gearboxes very well, and that combined with the hole we had in the frame for intake resulted in the bot bowing inwards and twisting the wheels/axles out of alignment. The wheels were actually hitting the metal of the base. This was probably exacerbated by turning scrub, since all wheels were on the same level. So, we took the bot apart multiple times at competition, which was a pain with the KoP base.
We aren't trying to rebuild the same bot though-we're entirely redesigning.

Also, with 6 8-inch wheels, it was a really really tight fit. We had to trim down the bars perpendicular to the wheels so that they wouldn't hit the metal. Also, does the KoP base have pre-drilled holes that would let us drop wheels a good distance?

The AM2494 and 221's chassis seem simple and stable, but would we be able to drop wheels with them?

After reading through, we're leaning towards the VersaChassis. Also, using four Colsons and four pneumatics sounds good. When teams go over obstacles like the cheval and moat, they tend to fly over and then land. Is stress upon landing an issue with the Colsons?

Thanks so much for the help, everyone!

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

[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 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.

[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.

[Billfred]

Originally Posted by redfancy

Ok, to answer some questions:

We are planning on taking the new bot to an offseason event, probably Calgames. Our old bot ran a KoP 6WD with 8-inch pneumatics. We had major issues with our gearboxes, which happened to be the exact same 3-CIM ones suggested before. Since the only thing we could do was defense, our gearboxes took a lot of stress and it was enough to fracture and completely shred our aluminum gears. We were advised to just use 2-CIM systems in the future and also decent steel gears.
Also, we didn't secure our gearboxes very well, and that combined with the hole we had in the frame for intake resulted in the bot bowing inwards and twisting the wheels/axles out of alignment. The wheels were actually hitting the metal of the base. This was probably exacerbated by turning scrub, since all wheels were on the same level. So, we took the bot apart multiple times at competition, which was a pain with the KoP base.
We aren't trying to rebuild the same bot though-we're entirely redesigning.

Also, with 6 8-inch wheels, it was a really really tight fit. We had to trim down the bars perpendicular to the wheels so that they wouldn't hit the metal. Also, does the KoP base have pre-drilled holes that would let us drop wheels a good distance?

The AM2494 and 221's chassis seem simple and stable, but would we be able to drop wheels with them?

After reading through, we're leaning towards the VersaChassis. Also, using four Colsons and four pneumatics sounds good. When teams go over obstacles like the cheval and moat, they tend to fly over and then land. Is stress upon landing an issue with the Colsons?

Thanks so much for the help, everyone!

From working the AndyMark booth at Championship, I can say you were far from alone with aluminum gear issues this year. (I'm betting you busted the smaller ones first.) Aluminum gears are a nice way to get the edge with a flat field and west coast drive, but they do run up against limitations when subjected to the abuses of this game (both the field defenses and the bigger wheels increasing the loads). If you've got the ToughBox Mini from the kit, give it a look; its steel gears will be plenty for the off-season. You can then use those lessons learned to assess how exotic next year's drivetrain needs to be. (I should point out, 4 of the 5 regional wins I've been around for were with the kit frame; 3 of the 4 had the that-year's-kit gearbox and the other ran the AndyMark 3CIM4U upgrade.)

The Team Cockamamie Robot in 3 Days build also ran an open front and saw the same frame bending you describe on a smaller scale before we parked it--it also had a way-too-small bellypan in hindsight and suffered for that. You aren't going crazy there either. Strongly consider a sturdy plywood bellypan on your offseason robot; it will lower your CG a bit and give you some great resistance against twisting and bending.

If you're using the AM14U3 with 8" pneumatic wheels, there are different hole placements and belts you're supposed to use. They sold them as a kit, which would place the axles at the correct place to avoid notching the end bumpers. It would also space the outer plates out further to cut down further on rubbing.

We didn't drive the Team Cockamamie robot on carpet or at high weight (we were waaaaaaay under), but the drop was enough for that. You can also play with air pressures there; a little less pressure in the corner wheels will increase the effective drop.

4901 used a variation on the 221 chassis for its drivetrain this year, except we knew we wanted drop (especially since our corner wheels were pushed inboard). We ended up using 1x3 tubing for the drive rails, which was overkill but suited the purpose of putting our axle holes exactly where we wanted.

Hope some of these data points help!