Help. I want to start a before season project to build a drive system on 4X3X.125 rectangular aluminum tube but my local suppliers (Midwest Metals Warehouse and Metal Express) do not carry it. Where else can I get some cheap?
Thanks
Bruce
Try metalsdepot.com
They’ve got 6063 aluminum tube in that size for ~$100 (8’ length).
They ship from Kentucky.
Try onlinemetals.com, they’ll even give you a discount if their website is linked from your team’s website.
http://www.onlinemetalstore.com is located in Minneapolis, MN and has 4"x2"x1/8" if you aren’t rigidly tied to the 4"x3" size. Of course, I am biased about them. They have been a very generous sponsor of our team.
Why so big anyway? Most frames I have seen being built are based on 1"x2"x1/8". See http://www.team221.com as an example.
Just a guess, but larger tubes are ideal if you wish to mount wheels inside the tube with pockets on the top and bottom, rather than cantilevered. Team 221 actually has a 4x3x1/8" tube for their Rock Box.
4 x 3 x 1/8 wall is a pretty strange size for aluminum tubing. None of the suppliers listed here carry it save for metalsdepot.com, as David mentioned.
The $107 price should give you an idea of how strange it is. At that price, it may be a custom extrusion – though one they obviously have a die for.
You should put on emphasis on designing around materials that are easy to acquire. 2x4x1/8 is much more easily available.
Wow, that is practically highway robbery. I agree with everyone else. Find another readily available size and design around that.
We get our 4"x3" tube from Alro or Clinton Aluminum.
You should put on emphasis on designing around materials that are easy to acquire.
This is great advice. If you can’t find it on McMaster it is most likely not a standard component that is readily available.
That said, 4"x3" tube is available from McMaster. 
I only see 1/4" wall available on McMaster. Am I missing it?
I only see 1/4" wall available on McMaster. Am I missing it?
I stand corrected. :o
We definitely buy it from Alro, laser cut for the Rock Box. I could have sworn that I bought a length from mcMaster at some point. Guess not.
If you really wanna have fun, try designing a robot around the materials you can buy at your local hardware/building supply store!
Although in the grand scheme of things, paying $100 or so plus shipping for the main vital part for your chassis isn’t too bad, as long as the rest of it is not very expensive.
we are lucky enough to have a regional metal supplier that makes all types of metal.
i do know that they stock that size of aluminum even though it is not on the website. i dont know about pricing however.
they do have 2 by 4 by .125