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moonlitewelder
08-28-2007, 06:57 AM
I am playing around the idea of building my own bicycle frames ... using Alum.

I have heard that the frames / Alum is heat treated to further strenghten the metal... what is this all about? Can one buy heat treated tubes and then proceed to build what ever the job asks for or is this something that is done once all the welding is complete?

Is this a necessity - for bike frames?? If so, can the hobbest take such items to a shop to have this done... and what how much money are we talking...

I really want to use Alum instead of CoMolly to save on some weight.

Any advice / info will be greatly appreciated.

TimS
08-28-2007, 08:27 AM
I'm certainly not an expert, but I do bike a lot and have poked around on some bike companies websites. I believe that the frame needs to be heat treated after welding, and that all companies building aluminum frames do this. That impression is based on a report of someone stealing a bike made for a show - in the report they mentioned the frame was useless, because it had not been treated and would break the first time it was ridden.

If you can find a local builder who works in aluminum, or perhaps a powder coater, you might be able to talk them into some deal. I don't think heat treating is rocket science, just raising the temperature to a specific heat for a specific time period.

Tim

Rick Moran
08-28-2007, 08:55 AM
When you weld aluminum is loses strength depending on how much heat you put into it, and the structural requirements. For stunt or off-road type bicycles, I would think that additional HT after fabrication would be required to assure consistancy. This can be done by a local foundry for a nominal fee. Like Tim said, right temp for a specific length of time. You would need to know what hardness you want it to be though. They work in Rockwell scale so you would have to spec something like 75-80 Rockwell. Too hard and it cracks, too soft and it bends. I'm not an engineer and there is a science to knowing what would be appropriate for your application.

Rick Moran
08-28-2007, 09:15 AM
A quick search found this website that has more info than you can probably digest. It has alot of info about bike frame materials and welds just to show how much engineering goes into a good frame.
http://www.bobbrowncycles.com/eng.htm

moonlitewelder
08-28-2007, 11:10 AM
A quick search found this website that has more info than you can probably digest. It has alot of info about bike frame materials and welds just to show how much engineering goes into a good frame.
http://www.bobbrowncycles.com/eng.htm


Thanks for the info! - well I do want to use Alum... and there are several independent frame builders located in MA, near where I live, so will get in contact with them... also will be checking out that web site.

Thanks again.