FRC Gearboxes, Drive Train and motor combination recommendation

[Coach Seb]

Alright... second season team here and we would like to investigate other drive train system than what is send out with the KoP.

Last year, we used the Rhino track and also experiment with pneumatics wheels mounted on the Andymark 14U with upgraded kit... We used the standard tough box mini gearbox.

I am looking at other system, gearbox and shifter and 3 CIM versus 2...

I would like to hear what your team favorite drive system is and why. What are pro and cons of your favorite, what you used in the past....

I understand that ultimately the game will make us determine what we should use, but assuming a flat surface with limited obstacles or "defenses" to go over....

[Knufire]

Are you looking for different powertrain options (number of motors, shifting vs no shifting, number and type of wheels) or different frame options? The AM14U3 is configurable; while there's the single configuration that is supported out of the box, you can purchase additional wheels, pulleys, belts, and gearboxes from AndyMark to add additional motors, shifting, or change to a number of wheel configurations. Picking these are typically based on desired performance characteristics of the drivetrain based on the game.

However, frame type (KoP, 2x1" WCD Frame, Sheet Metal, Plate Drive, etc) is something I typically like to consider separately. They all have their advantages and disadvantages performance-wise, in terms of ease of mounting superstructure, modifications for a large angle of attack for obstacles, etc, however, I think the overriding factor in choosing a frame type is your team's manufacturing resources and what would be easiest for your team to manufacture.

[Ty Tremblay]

RSN got together on an episode of Behind The Lines (before we were RSN) and shared a solid approach to choosing a drivetrain:
https://www.youtube.com/watch?v=6lmKLTZZLBE

[wilsonmw04]

Greetings,
The drivetrain is undoubtedly the most important decision you will make in a build season. You are entirely correct in stating the game will determine what type of drivetrain you will need this year. That aside, there is one drivetrain that consistently performs well for FRC teams of all shapes, sizes and ability levels. That is the classic six wheel skid steer with a center wheel drop. There are many combinations of wheels, gearboxes and motors that have proven successful. 1114 Kitbot on Steroids might be a good place to start your research. http://www.simbotics.org/resources/kitbot

[billbo911]

Originally Posted by wilsonmw04

..... That aside, there is one drivetrain that consistently performs well for FRC teams of all shapes, sizes and ability levels. That is the classic six wheel skid steer with a center wheel drop. There are many combinations of wheels, gearboxes and motors that have proven successful. 1114 Kitbot on Steroids might be a good place to start your research. http://www.simbotics.org/resources/kitbot

I want to second this comment. Until you are ready to, and capable of, creating and building your own drive-train from scratch, this is the way to go. We used this approach several years in a row. When we did, it was reliable and sturdy. In fact, we use a few concepts from it to this day in our designs.

[Billfred]

Originally Posted by Coach Seb

Alright... second season team here and we would like to investigate other drive train system than what is send out with the KoP.

Last year, we used the Rhino track and also experiment with pneumatics wheels mounted on the Andymark 14U with upgraded kit... We used the standard tough box mini gearbox.

I am looking at other system, gearbox and shifter and 3 CIM versus 2...

I would like to hear what your team favorite drive system is and why. What are pro and cons of your favorite, what you used in the past....

I understand that ultimately the game will make us determine what we should use, but assuming a flat surface with limited obstacles or "defenses" to go over....

The best drive systems accomplish three things, for me:

1) My team (in that year) can put it together quickly.
2) My team can make it come apart reasonably quickly for maintenance.
3) It will slip its wheels in the lowest gear in a dead push, rather than stick and trip breakers.

Everything after that is either taste or an optimization to make the robot more effective in some other game-specific way (say, open fronts or optimizing time to sprint a certain distance).

Over the five regional wins I've been a part of, here's what they used:

2010 (1398, Palmetto): Custom sheetmetal frame, guts of an AM Shifter, 4" wedgetopped wheels.
2011 (2815, Peachtree & Palmetto): AndyMark C-Base, CIMple Box, 8" wedgetopped wheels. (Other than the wheel change and maybe some sprocket choices, this was the kit drivetrain of the day.)
2012 (2815, Palmetto): AndyMark C-Base, CIMple Box, 6" FIRST Wheels. (This was literally the kit drive system, we just used frame bits to raise most of the frame in a failed attempt to clear the center bump.)
2014 (4901, Orlando): AndyMark AM14U, 3CIM4U gearboxes, 4" HiGrip Wheels. (This was the kit drive system, but with different gearboxes for 6 CIM drive as we expected to do more pushing that year and wanted to spread the load.)

If you haven't guessed, drop-center 6WD (as done in the Kickoff kit drivetrains) has been our weapon of choice over the years. To do otherwise requires a clear advantage once we analyze the game.

Take some time and get familiar with JVN's fabulous spreadsheet, get familiar with wheel options (cough cough shameless plug cough), and start figuring out your capabilities. If you've got means to do a tube-based or sheetmetal or otherwise custom drivetrain, great! If you don't, that's okay too--a solid drive system can be had out of the Kickoff kit drivetrain, though that might guide some other choices in gearboxes or wheels so you don't have to notch things or add other brackets.

[cbale2000]

Originally Posted by Billfred

...get familiar with wheel options (cough cough shameless plug cough), and start figuring out your capabilities...

Personally I prefer using Vex wheels on our drive system due to the Versa pattern they come with (which allows us to conveniently mate them to VexPro gears), HOWEVER, I can say that if AndyMark just so happened to carry Pebbletop tread in a 1.5" wide variety we would be buying a LOT of it (We've tried cutting it ourselves but it always ends badly).

Also, any chance you could post CoF numbers for the Tan Nitrile Roughtop and Wedgetop tread?

[Billfred]

Originally Posted by cbale2000

Personally I prefer using Vex wheels on our drive system due to the Versa pattern they come with (which allows us to conveniently mate them to VexPro gears), HOWEVER, I can say that if AndyMark just so happened to carry Pebbletop tread in a 1.5" wide variety we would be buying a LOT of it (We've tried cutting it ourselves but it always ends badly).

Also, any chance you could post CoF numbers for the Tan Nitrile Roughtop and Wedgetop tread?

It would be non-trivial to get the width in there, but I'll inquire.

I don't have the exact numbers for those two treads (and they're in the discontinued category so proper testing isn't going to be a top priority as we rush for Kickoff...), but Ike's vintage post and past conventional wisdom say a number in the 1-1.3 range is probably close to reality.