pic: FRC488 - Fall Project, Rev. A

[Madison]

Now that I've got a bit more time, I can write a bit more about the changes I made between the first iteration of this design and this one. Most of the changes were directly influenced by feedback I received in the other thread. I appreciate everyone's feedback and questions.

Wheel Modules:

• Added vertical flanges along the front and back edge to tie into the
  belly pan.
• Replaced 3/8" hex standoffs with 3/8" round spacers and 10-32 bolts inside. I stayed with 3/8" here rather than 1/2" since the VexPro gears' 1/2" hex bore can rotate freely about a 3/8" spacer and probably won't do so around a 1/2" spacer. We could open the bore on the gears up on a drill press since concentricity of that hole is not a concern, but I am not sure the switch to a 1/2" spacer is worth the effort. It's possible to change my mind.
• Haven't yet decided between a long spacer or a shaft collar to locate the idler gears axially.
• Swapped the 35 tooth idler gears for 48 tooth gears; this allowed me to move the idlers upward some, creating clearance below to extend the belly pan to the outer face and adding torsional stiffness to the module via the now offset wheel / idler spacers.
• Eliminated the hole-slot pattern for a simpler hole pattern. The hole on top will get shifted toward the outer edge; I see now that I moved them the wrong way yesterday.
• Reworked ball shifter mount and added captive nuts to the inside face of the module to accept the transmission bracket. The transmission can couple to any of the three inner wheels.

Belly Pan:

• Extended the belly pan to outer face of wheel modules and added short flanges to couple the outer module face to the belly pan with rivets.
• Removed taper from front and rear flanges.
• Our electrical system layout is not in my sphere of influence, so I will need to provide several mounting options and they will give me a board of their own design to couple to the belly pan.
• Added battery box. I will redesign this tonight; I am not happy with it and it can be one part instead of two.