Where to buy mechanical prototyping / experimental equipment?

I need to make some precise measurements of the mechanical properties of a device I am working on.

I will need to mount the device on a secure platform approximately 12" x 12" in diameter, mount some sensors to the platform and device, along with some other equipment - an electric motor to rotate another smaller platform, a micro controller board and power supply, etc.

This is sort of a new field to me. I am looking for a supplier that I can buy a lot of the mechanical equipment from (the platform itself, mounting brackets, bearings, etc.), that will all be compatible with each other, so I don’t have to mess around with drilling and threading holes in sheet metal, buying tiny screws, and all that shit myself.

I guess I am sort of looking for an “industrial-strength Lego” prototyping system, made of metal instead of plastic. I could probably actually use Lego, but there is too much slop and play in Lego mechanisms. I could look at something like Meccano, but I would prefer a product that is not marketed as a toy.

Maybe try the 80/20 system? It’s branded the “industrial erector set”. I helped on a project where we used it to make the structure for what was essentially an array of single-purpose microscopes. I thought it was pretty useful stuff.

I found this company. They are pretty close to what I’m looking for, although they have a pretty limited range of components (no bearings, few joints, etc.) Also, it does not appear that they supply a metal platform to affix things to.

Any other suggestions are welcome!

I found them as well, but their stuff is too large. I’m looking for something that is tabletop-scale.

80/20 comes in many different sizes. The smallest ones are 1"x1" cross section, which may work for a tabletop-size setup.

Depending on your precision and cost requirements, an optical table might be appropriate. The standard optical bench has 1/4"-20 threaded holes on a 1"x1" grid pattern (or M6 on a 25mm x 25mm pattern if you get a Metric setup), and there is a lot of hardware designed to work with these standards - adapters, holders, motion stages (both manual and motorized), precision scissor jacks, etc.

I can’t think of anything of that scale (smaller than 1" 80/20) off the top of my head. If there is it will be spendy.

You might want to poke around here:

http://us.misumi-ec.com/contents/mech/modular/

IIRC, Misumi will do machining for you.
Not exactly what you are looking for but there are modular fixturing systems for machining. They have a grid of dowel & tapped holes.

http://www.carrlane.com/catalog/index.cfm/

Check out optical equipment like base plates and tables, posts, clamps, positioners, jacks, and so forth. Edmund Industrial Optics, Thorlabs, and Newport are three favorite companies. The point is to put lenses, mirrors, and what not exactly where you want them. It’s about as versatile as 8020 (which I also love) but tends to favor smaller constructions. Excellent stability.

I have used Unistrut to build things. Awesome product, though their product line is more geared toward for structural stuff. May want to look at their full catalog to see if they have anything that might be useful.