Structural Framing Strength?

[pfreivald]

We've used Bosch Rexroth for linear motion applications--their drive carriage is fantastic. 30x30 is overkill for most applications, though.

The kitbot drivetrain is sufficiently good that I certainly wouldn't use structural framing for it....

...and for upper mechanical work, with limited manufacturing capabilities I don't think you can go too far wrong using square tube stock, L-stock, and clinch nuts (aka rivnuts aka rivet nuts aka threaded inserts). A couple of bags of 10-32 clinch nuts, a thread setter (the tool used to install them), 10-32 socket head cap screws, and some 19/64 drill bits will go a long way toward cheap, do-it-yourself, easy-to-modify-and-install "structural framing" that is versatile for prototyping, and easy to lock in place with a little Loctite for use on a competition robot.

It takes a more effort than an off-the-shelf solution but is far cheaper and lightweight, it isn't as lightweight or as sophisticated as CnC sheet metal fabrication but requires virtually zero expertise and is more modular. It's a happy medium between the two that I wish I'd known about as a rookie.