Modular Building Systems

[GeeTwo]

Thanks to our trip to CMP this year, we've stepped up our fund-raising capability and anticipate a larger budget for next year's build. As a team with no in-house machining capability beyond a chop saw and a drill press, and not enough mentor knowledge to justify increasing by more than about one new tool a year (unless we find a machinist mentor), we're looking for alternatives.

For the rookie Rebound Rumble year, we chopped up a KOP chassis to make a ball intake, then overloaded it with a tall frame of 80-20, resulting in a wonky top-heavy 'bot. I think we're still sweeping up shavings from that swiss-cheesing. The next two years, we swore off kits and prototype systems and used aluminum angle and channel, but due to time constraints, we had to use our withholding allowance to finish up our manipulators. This year, we forgot to opt out of the KOP chassis. Once we had our requirements, strategy, and basic architecture, we realized that the KoP Chassis could be modified to meet our needs - and could have done so every year so far. We actually had both our practice and competition robots operational before stop build day and changed our decision as to which was which about lunchtime on Washington's Birthday. However, we still struggled to fabricate a simple manipulator design, and though we continued to try things between Bayou and CMP, our robot at CMP was essentially the same one we competed with at the regional because we couldn't get those great ideas built stiff enough, or light enough, reliable enough, or within the transport configuration.

After seeing some of the great robots at CMP built on VersaFrame, we're thinking that this or a similar system might help take our fabrication abilities up a notch. We also have an incoming student who's learning CAD (he cadded up some of our parts for external machining this year), and we're looking at a 3-d printer to make sensor mounts and oddball adapters.
I did find a nice thread singing the praises of the Vex Versaframe system . I also have a catalog of the Tetrix Systems; Tetrix Max looks useful.

So here are the questions:

• Are there any other modular building systems we should consider, or perhaps just an source of pre-drilled extrusion and gussets that could provide a similar advantage?
• What are the relative strengths and weaknesses of the different systems (including strength, cost, quality, flexibility, and ease of use)?
• How well/poorly do each of these systems interface with each other, the KoP chassis, FRC-legal motors, and off-the-shelf and custom-made sensors and manipulators?
• Do you have any other info that would help with deciding which (zero or more) of these systems we should adopt?