pic: Klein Bots 3735 2015 Offseason Drivetrain Project CAD Rendering

[notmattlythgoe]

Originally Posted by Kevin Ainsworth

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?

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.

[Jay Burnett]

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?

[notmattlythgoe]

Originally Posted by Jay Burnett

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?

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.

[Everett33]

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.

[AllenGregoryIV]

Originally Posted by Everett33

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.

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

[lewislongbottom]

Originally Posted by Everett33

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.

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.

[swaxman12345]

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.

[asid61]

Originally Posted by lewislongbottom

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.

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.