[pfreivald]

Originally Posted by AllenGregoryIV

Why did you decide to go with the octagon frame instead of a hexagon?

While a circle maximizes area (and a hexagon better approximates that), we wanted to keep a wider wheel base.

Originally Posted by AllenGregoryIV

Any reason the belly pan isn't incorporated into the front and back rails as one piece? (971 style, also extending the front and back rail flanges and adding an extra bend to them to make them more box like, again 971 style.)

Our sheet metal sponsor is used to building giant buses, not small parts, and gave us a lot of pointers on what would work well for their people. To whit, more, simpler parts with fewer bends where possible. This has resulted in some compromises between what we feel would be ideal and what they want to work with!

Originally Posted by AllenGregoryIV

Do you change the gearbox when you switch from 4" to 6" wheels?

Nope! The plan is to have a drive train that's easy to modify to one or the other, but it's not something we intend to change "on the fly."

Originally Posted by AllenGregoryIV

Also what is the sheet thickness?

0.090"

Originally Posted by colin340

-why five shaft??? yes it keeps the mass centers but robots are rarely 100% symmetrical. i see it as an added fail point, justin claims it make the tranny easier to change and gives you a 100% symmetrical start

The five shafts are because of the modularity of 6 wheel vs. 8 wheel.

6 wheel would be more traditional WCD, with a direct-driven center wheel.

Originally Posted by colin340

-atop the bumper mounting surface the hole pattern changes from outer to inner

I'm not sure what you mean. Can you clarify? (I think that's an artifact of the image conversion process, and the fact that due to belt interference, rivet nuts go from one side to the other as you traverse the main drive shaft.)

Originally Posted by colin340

-how do i change a belt?

Take off the bumpers, pop off the wheels (clip rings), and then with a few loosened bolts the flat panel (with attached 1x3 bumper supports) comes off (leaving the corner brackets in place). Depending on where we mount upper mechanical stuff, we made the top parts all modular and easy to access, just in case we have to add a step to that. At this time, I believe twelve bolts (that we have easy access to) and we can slide the whole side panel off.

I mean, we've never had to replace a sprocket or belt in our drive train since switching to belts way back when, but that doesn't mean it can't happen!

Originally Posted by colin340

-the belly pan should be notched so the tranny can slid back that length of the output shaft TRUST ME I MESSED UP!

What's the advantage to backing up the transmissions further into the robot? As-is, the extra piece of axle won't touch anything (and we can always trim it if needs be.)

Originally Posted by colin340

- I would add more mounting holes atop each "drive rail" so the hole pattern matches the front and back rails.

I agree, but that's actually going to go the other way--the front and back rails are the 1x2" C channel from VexPro, but we just found out they're discontinued. Our sponsor wants to see fewer tiny holes where possible to minimize time on the machine (from starts and stops), so we may end up with even fewer than are pictured in the front and back, and then end up drilling more on a press using a template.

In a perfect world, during build season we'll figure out exactly which mount holes we're going to use and delete the rest of them in favor of larger lightening holes/slots.

As to the bumper shape: that's an excellent idea. T'would require some non-trivial re-design of what we've got here, but that's the whole idea! I'll bring it up to the team.

Thanks for the feedback so far!