pic: Klein Bots 3735 2015 Offseason Drivetrain Project CAD Rendering
 

Re: pic: Klein Bots 3735 2015 Offseason Drivetrain Project CAD Rendering
 

Looks nice! It looks like 148 was a bit of an inspiration (correct me if I'm wrong). Does it use chain-in-tube or are the chains just not shown?

Re: pic: Klein Bots 3735 2015 Offseason Drivetrain Project CAD Rendering
 

This offseason, the Klein Bots decided to design a WCD Chain-In Tube drivetrain. We wanted to experiment with different options and features, so we went with a modular design strategy.

We wanted to have a versatile drive-base configuration; so we now have options to test an 8WD, 6WD, and 4WD drivetrain just by changing the configuration of the drive-tubes.

We also have pockets in the bellypan to move the position of the gearboxes; which are the VexPro 2 CIM Ball Shifters, this function just gives us more options if we decide to change positions to accommodate different drive configs.

We also designed what we call the "Wings", they were inspired by FRC Team 148 on their experimental drivetrains. We aren't getting these fabricated right now, this will be a future addition (hopefully).

This will be our first WCD (and Chain-In Tube) so we hope to learn some things before the coming build-season if we do decide to go ahead with this design.

Re: pic: Klein Bots 3735 2015 Offseason Drivetrain Project CAD Rendering
 

What type of wheel drop do you plan on running?

Re: pic: Klein Bots 3735 2015 Offseason Drivetrain Project CAD Rendering
 

We don't have a drop in the CAD, however I believe the plan is to use traction wheels and rivet an extra layer of tread on top of the existing tread. It should give us enough lift on the center wheels to avoid wheel scrub.

Re: pic: Klein Bots 3735 2015 Offseason Drivetrain Project CAD Rendering
 

Just be careful: that means the edge of your center wheels will be moving faster than the edge of your outside wheels. This could cause some weird driving experiences as the bot "rocks" slightly, putting more weight on the front, back, or center wheels.


Also, what are the giant holes in your bellypan for? Is there a mechanism being designed to go there?

Re: pic: Klein Bots 3735 2015 Offseason Drivetrain Project CAD Rendering
 

Several other teams are currently doing this already. The speed difference tends to be negligible.

Re: pic: Klein Bots 3735 2015 Offseason Drivetrain Project CAD Rendering
 

We will keep that in mind.

"We also have pockets in the bellypan to move the position of the gearboxes; which are the VexPro 2 CIM Ball Shifters, this function just gives us more options if we decide to change positions to accommodate different drive configs."

Re: pic: Klein Bots 3735 2015 Offseason Drivetrain Project CAD Rendering
 

I'm curious about the short length verses wide width when the center wheels are touching the carpet but the outside wheels aren't. During acceleration the four back wheels are the only ones touching and that scares me also. Our experience is that this makes for a twitchy bot when turning and an unstable bot when trying to drive fast in a straight line. Anyone have experience with this?

Re: pic: Klein Bots 3735 2015 Offseason Drivetrain Project CAD Rendering
 

Why not go with omniwheels on the corners so that there is no need for a drop. It seems like that would result in a more stable robot than any drop center and it eliminates the need for different diameter wheels.

Re: pic: Klein Bots 3735 2015 Offseason Drivetrain Project CAD Rendering
 

Teams have been running 8WD robots in this configuration for years without issue. The same could be said about 6WD drop center robots only running on 4 wheels at a time and yet it is probably the most popular setup in FRC.

Re: pic: Klein Bots 3735 2015 Offseason Drivetrain Project CAD Rendering
 

Just for thought's sake, what would be the trade-offs of switching the 4 corner wheels out for omnis? Did you guys think about doing this at all? And if so, why did you decide against omnis?

Re: pic: Klein Bots 3735 2015 Offseason Drivetrain Project CAD Rendering
 

I believe you'd be lowering the amount of traction you have because you'd be taking some of the weight off of the center traction wheels and moving it to the omni wheels.

Re: pic: Klein Bots 3735 2015 Offseason Drivetrain Project CAD Rendering
 

Is there a reduction between the gearbox output shaft and the wheels, or is a direct drive? If it is a direct drive, using the JVN Spreadsheet gives this chassis an adjusted speed of 20.5 ft/s, which is extremely fast.

Re: pic: Klein Bots 3735 2015 Offseason Drivetrain Project CAD Rendering
 

Good catch the 2 CIM Ballshifters are normally used with a third stage when doing a west coast style direct drive setup.

Re: pic: Klein Bots 3735 2015 Offseason Drivetrain Project CAD Rendering
 

Good catch! thanks, I will let the mechanical team know about this and we will figure something out.

We can easily change the wheels out, we would rather learn and see the differences ourselves to make our own decision. But thanks for raising that point.

Re: pic: Klein Bots 3735 2015 Offseason Drivetrain Project CAD Rendering
 

If you look at the Duluth East Daredevil's robot from last year, we mounted most electronics on the vertically on the battery stack. Have you considered doing that? It might save some bellypan space, depending on what you want to use the robot for in the long term.

Re: pic: Klein Bots 3735 2015 Offseason Drivetrain Project CAD Rendering
 

If you switch the pinions on the cims to the 11t pinions that Vex offers, your free speed goes down to 23fps, which is still extremely fast. Then switching to 3.25" Versawheel DTs with the pinions is 18.8fps. Going to 3" colsons with the 11t pinions gets you to 17.4fps free speed, which although fast is still ok for a 4-cim drive.