I have been working with 6061 for the past few weeks and having a blast. I just finished a BMXish 24" wheeled bike and have a few track bikes going now with aerodynamic tubing. Ill get the track bikes up when I get a little further along.

I made many of the parts of this BMX frame. It has a butted top tube and seat tube but the balance is drawn straight gauge. The dropouts are slotted 12mm through-axle with built in tugs but only the set-up parts are shown.


30 418 by frankthewelder, on Flickr


30 419 by frankthewelder, on Flickr

By flipping a brake adapter around I was able to make a brake mount that allows over 25mm of wheel adjustment with good pad coverage but rotating the assembly on a slot.


30 420 by frankthewelder, on Flickr


30 421 by frankthewelder, on Flickr

massive 49mm head bearing holes and shaped gusset.


30 422 by frankthewelder, on Flickr


30 426 by frankthewelder, on Flickr

Your welds look great. I have welded a many years i love aluminum, will the frame be heat treated?

Thanks for the kind words!

Yes, I get them done in Quincy at Industrial heat treating. I have an alignment set up at their plant for the final operations.

I really like the logo on the seatstay and chainstay gussets. Is it new?

Yes, It's pretty new, 2011 or so.. Thanks!

I love the aluminum work you do. Beautiful welds. I would like to do some myself, but the heat treating is a real barrier for me.

It is a major hassle. A lot of the expertise that is required comes from the folks who do the heat treatment so the right place is important. As far as a structural material for making bikes, It's pretty amazing stuff.

I am trying to press form a tapered head tube that is 1-1/8 integrated at the top and 56mm at the bottom. It's not working yet..

Here is a aerodynamic frame I finished yesterday,


frames 023 by frankthewelder, on Flickr


frames 022 by frankthewelder, on Flickr


frames 019 by frankthewelder, on Flickr

Nice work !

Thanks neighbor!

Very nice. Looks like that frame needs a 2" lower cup! What kind of fork does it take?

A lot of folks enjoy the challenge of welding aluminum, it is one of those things people try just as a hobby. FTW, can one weld stuff like stems, racks, and do the heat treating in the home oven. I was thinking it might even be possible to go up to stuff like rear ends. The technology to mate rear ends to front ends of dissimilar materials is pretty well know. Though normally done with carbon.

The lower cup is 56mm or so (without measuring it) and is onepointfive zerostack. The top of the head tube is 1-1/8" integrated.

You need to be able to heat stuff to 970F or so and quench in to room temp in under 3 mins. to heat treat 6061. I think many kilns go hotter than that.. you also need to be able to make the stuff straight and age it to full hardness at around 500F

Wow, I thought it was cooler for Al, for some reason. I guess it is cooler than steel, but that isn't saying much. I'll have to pass on that. It is easy to get electric kilns, for pottery. The come up around here for free, but as you say, heat is only part of it.

7005 aluminum ages at 600F. but it's very rare material except for bicycle tubes.

Wow, those are gorgeous welds. So envious of this kind of talent. I've been looking for someone local to repair a cracked chainstay for me, but no one will touch it since there isn't a heat treating facility nearby. One of my friends offered to hack a commercial oven, and there was some talk of building a big assed bonfire. The problem would be staging it down to room temperature. The suggestion was, if I remember correctly, 15 or so mins at the upper limit, then another 15 mins at somewhere in the mid 200* F range, then finally room temperature. I'm not sure on the numbers. I guess this is the critical process to maintain the best integrity. I also heard rumors of a chemical treating process, but I don't know how credible that information was. I've been thinking about calling Sherwood at Ventanna to do the work. I found another chain stay, but I wouldn't thing twice about repairing the old one as a spare if the opportunity ever presented itself. I also have a chain stay that I'd like to shorten to correct some funky geometry. I guess I should have invested in steel!

Oh, and that BMX frame looks tits. Has it been built up yet? What are the numbers?

Thank you for the compliments. I have been welding for a really long time and enjoy my work.

The customer just got it together. Ill ask if I can share the geometry.

Depending where the crack is, heat treating may not be required or even desirable. When aluminum get's to the 950, the frame is so soft that they can be easily damaged. It's very difficult to keep them from moving enough to cause problems. I have seen tubes sag as much as 2" in the center so you need to have a lot of stuff around to get it straight.

I have a complete alignment and tube straightening set-up near the quench tanks. I get about 30 mins make them (six at a time) straight before they start to get stiff.

Serenety carbon with a tapered steerer. I think the lower cup is 55.9mm. I am at home in my jammies right now..

Thanks. The crack is at the weld at the vertical member and the seat stay yoke. There is also a hairline crack that has been there for a while I think running vertically at the drop out. The one on the weld looks pretty bad.

Haha, those were just some ideas some fella was tossing around. He's more of a computer guy than a welder. I'll look into the absense of heat treat, but the bike designer, NOT the fabricator, is the one who highly recommended heat treating in that area.

Pics?

It sounds like it's built from 7005 which would only require 600 degrees. 6061 is brought from 950 to room in under three mins which is about as fast as you can get a basket of frames from an oven to a big water tank with a forklift!

7005 has a completely different heat treatment process that is all 600 or under.
congrats on getting that word through lol.

Sorry, I meant the horizontal member (strut?) at the yoke junction. < my use of terminology probably sucks, but hopefully you get the picture. I had assumed 6061 as it's aircraft grade alum.

What word?