Welding and rewelding Aluminum bike frames

[Tanner]

Well, I figured it was about time I asked this question - I'd like to start making my own bicycle frames, and do a little bike repair on the side. In my particular type of biking....the riders are lucky to get 6 months out of a frame before it cracks and/or snaps. I was wondering what machine would be best for welding frames (renyolds 851 steel, 7005 AL, U6 alloy, 6061 AL, and cromo), and, is it possible to reweld an aluminum frame even after it has been heattreated? If so, how would you go about re-heat treating it? I've been welding for about a year now (smaw, mig and oxygen/acteleyne) and I know I want to use TIG for the welding/rewelding on the frames. Thanks all for your help.

[Paul Seaman]

Tanner:
This is going to be a balancing act between what you want and what it costs. Most of us know what we can afford to spend and this has a great deal to do with your choice. I am a mm210 owner and love it,with the spoolgun I've done some terrific Aluminum tubing welds, but for tig I am trying to save the money for a Dynasty 200DX. HAWK, Blondie, and Heiti are the real experts on tig machines I just haven't used them enough to tell you the benefits of one over the other.
Also if you have any dimensions on the materials wall thickness it might help in the suggestions. What kind of riding do you do that creats such bone crushing jars to break a frame that often?

[Blondie_486]

Tanner,

A synchrowave 180 would do the trick for about 1,600.00 or 1,700.00. If your budget will allow it the Dynasty 200DX is an excellent choice, it has a pulse feature that will shake the puddle and bring impurities to the top. It's a little more money by about a grand.

You need an AC/DC machine to TIG weld aluminum so stay away from the Maxstar line. They're good machines but they're DC only. I'm sure HAWK will see this post sooner or later and he'll vouch for the Dynasty 200DX. I've personally never used one yet but I can't wait to try one!! If I had the money I'd own a Dynasty 200DX based on what I've heard about them from people who have them.

As far as heat treated frames go, you can weld them but then you'll have to heat treat the frame again. If you're referring to a stress relieved chrome moly frame you can stress relieve the weld area with a torch by heating it to 900 degrees (check with a tempil stick to make sure the temp is right) then gradually cool it down. I don't know if you can do aluminum that way or not. You may have to do the whole frame again.

Maybe HAWK or Andy will know the answer to the heat treated aluminum.

Blondie

[Tanner]

I ride biketrials, which is like mototrials, but you're on a bike, not a motorcycle. I also race BMX bikes, and those crack too. BMX = bicycle motocross. The wall thickness of the metals I'd be welding are about 1.2mm give or take some. I'd like to keep the cost UNDER $2000 USD, but, if I have to, I can go higher. Might as well buy a quality welder right away than a "get-by" machine

[Blondie_486]

Tanner,

Well if you can afford it I've seen 200DX's going for about 2,600.00 on ebay through Indiana Oxygen Company and I believe BR Welder in Maryland is within a few bucks of IOC. They're both offering free shipping on most of their models and the 200DX is considerably lighter than the Synchrowave 180.

But I'll bet if you go to your local dealer and let him know what you can get one for on the internet with free shipping to your doorstep they'll do what my dealer did. Go just a few bucks under their prices and throw in a bottle for argon, or something else. But you'll also get local service too, if something breaks while under warranty you don't have to ship it all over timbucktwo.

Sharpen your knowledge, and cut a good deal!

Blondie

[Tanner]

Blondie,

I plan on going to my local welding supply store to apply for a summer job soon (I'm only 15, so, I need a job), so maybe I could even bring the cost of the welder down even more. I'll let the board know what happens. Thanks for the replies!

[Paul Seaman]

Tanner
When I was younger I rode pretty hard and only broke a couple of welds at the BMX track near us. Sound of it is pretty agressive, as blondie said I don't know about heat treating Al but I think all you can do is stress relieve it! Give it a couple of days and Andy will verify one way or the other.
Keep on, keepin on

[Blondie_486]

Tanner,

Yeah that's the ticket go to work for a Miler dealer then get the employee discount plan. Or perhaps a demo machine or a reconditioned machine or a trade in. Any of those should net you a decent discount.

Good luck and keep us posted

Blondie

[Blondie_486]

Tanner,

I'm old and have arthritis so riding a conventional bike is out for me. But I have been thinking about building a recumbent similar to the Easy 1, re-engineered to hillbilly specs of course. I'll most likely make a prototype frame out of mild steel and then think about either an aluminum or chrome moly frame. After I git all them thar bugs worked out of it!

Blondie

[Paul Seaman]

Tanner :
If your employer would have a demo model you might be able to take it home for a weekend and try it out make a few fixes and take it back on monday. Make friends with the guys and you never know who will jump in to help you out, It could be like some of the guys here and just say comeon over and try it out! Also don't forget there is an educational discount available on some equipment.

[HAWK]

Tanner,

First of all the Dynasty 200DX is the machine of choice for your work. Specific aluminum alloys are reweldable and re- heat treatable. You will have to do some research on the specific alloys as to what can be done. Also the filler rods for post treating of once welded aluminum can be more than a pain. They are expensive, hard to fine, and sold only in quantity.

[Tanner]

Originally posted by pjseaman
Tanner :
If your employer would have a demo model you might be able to take it home for a weekend and try it out make a few fixes and take it back on monday. Make friends with the guys and you never know who will jump in to help you out, It could be like some of the guys here and just say comeon over and try it out! Also don't forget there is an educational discount available on some equipment.

Yeah, the guys let me come in and weld some stuff back when I was in 4th grade, and when I went back in to buy some gloves and a helmet they couldn't believe I stuck with it for so long. They also couldn't believe bow tall I was! (I had to duck to walk in the store!)

[HAWK]

Tanner,

Most information I have found on heat treating 6061 and 7005 alloys does not recommend PWHT (post weld heat treating) as it requires heating to a temperature that causes loss of the alloy's mechanical properties. My guess is your heat treating will be in the form of incremental pre-weld treatment. Be thorough in your research for the welding of these alloys. Don't get you or someone else hurt or killed.

Attached is a filler guide with respect to strength, ductility, and crack resistance.

[Tanner]

Thanks a ton HAWK. Err, it doesn't seem to have the right file extension on it. I'll try and get it working, if not, I'll let you know

[Tanner]

yeah, I can't get it working. I have winzip, winrar and everything, but, this file just won't open. I even tried resetting the extension. that didn't work.

EDIT - Hoho! My reverse engineering skills paid off! Thanks HAWK!