I am wishing to build a model sprint car chassis. It has to be strong enough to withstand medium impacts at around 30 mph (radio controled and Nitro powered).
Im hoping I can use 4-5mm aluminium tubing. Bending wont be a problem, but fixing the pieces together is where my problem lies. I wish to do this at home and dont really want to have to buy any fancy gear. Butane powered solderer and some sort of solder?
Sounds like aluminum might be too much trouble to learn how to weld right - and you'd still need to buy some better equipment.
If weight isn't utterly critical on your model, I'd suggest either mild steel angle or strap or steel tubing for the chassis, either round or square. You can get a small oxygen-acetylene welding rig for under $100 if you look around at garage sales and pawnshops, and either gas-weld or braze the chassis together.
Or get a small wire-feed MIG welder to put the pieces together - looks a little rougher but it's easy to learn. For small tubing like that, the 'baby' welders that plug into household current are enough.
And welding may not be the best method for a high-abuse system like you describe - the Autopia cars at Disneyland started out with welded chassis like on a regular automobile, and the constant impacts from the slamming and banging meant the chassis were forever cracking....
So they redesigned the frames. Where the tabs and brackets were welded on, but the large pieces of the chassis rails were bolted together to allow controlled flexibility. They're still using those same car chassis 35 years later.
I might be misreading this, but I am hearing that this vehicle is going to be pretty damn small, How much is it going to weigh? . I would consider going with brazing instead of welding in this case. Home Depot sells a nice kit from burnz-O-matic with both Oxygen and Mapp Gas for about 30 dollars. Get a book and some tubing and have at it.
On Thu, 23 Oct 2003 19:52:02 GMT, someone who calls themselves "V8TR4" I would consider
Those Mapp/Oxygen Bernzomatic rigs are worthless - by the time you get the flame set right, the gas is running out. Be thankful you didn't try one of the Solid Oxygen Stick/Propane torches, they were even worse. (If such a thing is possible...)
If you want to go for something inexpensive and small but that will actually do work, they have the small Oxy/Acetylene "Tote-A-Torch" rigs (2 empty bottles, plastic tote, 2 regulators, torch handle, a few tips, twin hose, striker, etc.) at Home Depot - right next to the MAPP torches. Or at your friendly local welding supply, where you'll have to go anyways to get a set of full tanks and the other stuff...
About $250 - $300 new with empty tanks, or go find a good used set. Pawnshops should have them, they're the favorites of air conditioner repairmen that need to haul the torch around to braze in compressors on top of roofs and in attics.
Though with those itty-bitty tanks (10CF "MC" Acetylene and 20CF "R" Oxygen) you might want to buy & have a second set of filled bottles on hand, so you can switch and keep going when they run out.
Bernzomatic, the purveyors of propane torches etc, sells an aluminum "welding" rod that would work for this.
I've seen the stuff in every Home Depot store I have ever been in, so your local one likely has it.
What it is, is rods of zinc or zinc alloy. Silver color, sorta lumpy looking rather than like smooth wire.
They work pretty good, once you get the technique down. You will be able to build a decent fillet around your joints with very little practice.
Clean your surfaces with stainless wool or a stainless brush. Jig them in place (pop rivets maybe). Apply the heat with a propane torch. You want to heat the area slowly, not just one spot fast. Skritch at the joint area with the rod as the temerature comes up. When it get warm enough, the rod will stick to the aluminum, and flow out a bit. If you get it too hot it gets ugly, the zinc overheats, you get white smoke everywhere, and you have to clean the stuff off and try again.
If you do breathe the white smoke it may make you ill (zinc fume fever). Drink a lot of milk to offset the effects. Best to work outside.
This is the same stuff that you see at tool shows and fairs, being sold for a lot more money than HD will charge you, by a guy busy sticking pop cans together with it.