This is a group of modifications on http://www.thingiverse.com/thing:19170 by Krux. I stretched the chassis to tighten up the tracks and combined the 3 parts into one. I found that the original idler wheels were too loose on a standard 608 bearing so I reduced the diameter of the hole.
I extended the servo mounts up to meet the new top plate, and created the top plate to take a servo for future turret/head/upper body. The front plate mounts into a recessed area in the top plate which can be glued and screwed tight using the nano and uno plate mounting holes. As I used ABS, acetone glued it very well.
The Arduino nano screw terminal breakout board I used is a Deek-Robot nano terminal adapter v1.0 from e-bay.
An Arduino Uno bumper plate is also supplied to mount onto the front plate. All holes already in front plate.
Support is needed for the top plate (print inverted) and front plate (support everywhere) only, although if you want they can be used on the sonar plate as well.
Shell thickness is 2mm for some strength.
print speed was around 40 to 50 mm/sec depending on the complexity of the part.
Printed in ABS on a Rostock Max v2 printer
Once printed, the front plate, top plate and rear plate need to be glued and screwed together until the glue is set (ABS use acetone, works better than anything else.)
It may be advantageous to temporarily mount these parts to the main chassis in order to get things to line up perfectly. My rear plate ended up slightly too far forward which later caused problems lining up the servo plate mounting holes.
I imported the original STL parts from Krux into lightwave 2015 and made sure they were all centred properly (a little off on some things) then I spliced the front, main and rear chassis parts together, moving the axis holes and nose forward by 6mm.
The rest was designed to fit the new chassis and what servos I had to hand for the top (MS-626)