A guestion for any of you who have worked with aluminum

[Oak2004]

Having puzzled over how to carry loads on my wheelchair without destabilizing it (there's only so much you can put in a backpack before you're on your back looking up at the sky), I've come up with a design for carrying the weight much lower (centered on the wheel axles) and (on my chair anyway) not protruding beyond the wheel.

The design requires a frame made of aluminum tubing. Lacking the ability to use any fancy CAD software, I put together a not-to-scale model in Second Life, image below:



The tubes shown in red are one piece and bent to shape. Also shown is a reinforcing crosspiece and four clamps for clamping onto the wheelchair frame. The actual dimensions of the frame would be 10 inches deep, 11 inches high, and 23 inches wide.

Now here's my problem. I speak wood, and I speak plexiglas. I even speak electricity and roofing, not that either of these "languages" have anything to do with this project. What I am utterly illiterate in is metal.

I don't know what kind of tubing is bendable and what isn't (I do know, more or less, how it can be bent). I'm nearly illiterate in the very nomenclature for aluminum tubing. I'm aware of kee klamps and their cheaper cousins, but are there alternatives to the heavy steel clamps and the larger-than-necessary diameters of tubing they would mandate (included in that is are there "fabricate-it-yourself" clamp designs suitable here?). I know the crosspiece can ultimately be welded (I'd rather use a t-clamp until I'm sure of its positioning), but how would I either go about welding it (given my lack of experience with anything beyond soldering) or hire someone to weld it. Yep, I'm that metal clueless (unless you include how to splash roofing cement around flashing).

Any advice?

[Viva_La_Revolution]

1. any metal shop should be able to make this for you...

You may have to shop around a little to find someone good enough to help with the exact specs.

[Warpy]

2. I echo the above

and it would be a real plus if you live anywhere near a custom bicycle shop. Not only are there aluminum and aluminum alloys, there is also now carbon tubing, very light weight and strong.

It might also be worth your while exploring custom and sport wheel chair makers online. Your problem might already have been addressed out there by people who make chairs for hikers, ball players and racers. It's a very practical concern, and I'm sure somebody else out there must've come up with a few ideas or would like to share yours.

Good luck.

[Stinky The Clown]

3. I third this ......

....... necessity is the mother of invention. But I'd also bet you're not the first to have both the need and the solution.

I agree about a bike shop. They routinely work with aluminum (alloy) tubing. Aluminum is a funny metal. It does not act like steel. It is more brittle and more prone to breaking when bending is desired outcome. Welding requires different skills, too. By the way, many bike frames are brazed, not welded, largely due to the difficulties associated with welding aluminum (very large weld beads being part of that).

If it happens this is not an idea that's been exploited, consider developing it commercially. If you need it, rest assured others do too.

[Hotler]

4. I'd make it of alum. square tube and mitter the corners

at 45 degrees. Make sure to have it TIG welded and not MIG welded. 1" sq or 1 1/4" sq tube about 1/8" wall would work and may be found at some hardware stores. Maybe a small set of wheelie bars like dragracers use.

[ret5hd]

5. An experienced person speaking here:

Make it from electrical conduit first. You can borrow/rent a bender like this for next to nothing:


Connect the crosspiece with a conduit tee like this:


fashion your clamps from tees (with the top part of the tee cut off) and some hose clamps.

get it all fitting together just so... just the way you like it. Bring it all to a muffler shop in a poorer part of town.. They are used to welding/cutting thin-walled stuff and will work cheap. Ask them if they can fabricate a more permanent clamp than the hose clamps.