Wednesday, August 31, 2011

Drawing a Bead

Actually, more like pushing one.
Well, you can push or you can pull, either way I guess it's still drawing a bead.
Today, we got into some oxy-acetalyne stuff.
The students have already learned to used the cutting torch, instead of dicing something up, now they have to learn to put stuff together again.
I don't have much experience on the oxy-acetalyne torch.
Well, actually I learned how to cut sort of okay.
I mean you can't just light her up and go, you sort of have to look at the gauge of steel and adjust your heat or you produce way too much slag.
Slag being the melted stuff, you don't want to create too much to make a clean cut.
Anyways, today we switched off and put on a welding tip.
This is the hard part.
Making a pool and making a nice bead.
You've seen what a nice bead looks like, it's that welding mark on your bicycles that join all the tubes together.
Well, unless your frame is like brazed or lugged.
Or if your frame is made out of carbon goodness.
The oxy-acetalyne torch is used for the brazing part, not so much the welding.
Most aluminum or steel bikes are TIG welded, which stands for tungsten inert gas.
More on that later.
The welding I did was mostly MIG, which is metal inert gas, which is so easy even a caveman could do it.
Anyways, back to gas welding:

Here's the instructor pushing a bead using some filler rod.
You don't really need the filler to weld two pieces of steel together, but it helps to fill in the weld and you can dress it later.
This is sort of what brazing looks like, except brazing is not as hot and brass or silver is used as a solder.
One of the students trying not burn the building down:

I gotta say, oxy-acetalyne welding sort of scares me cause the acetalyne is like super volatile.
So volatile in fact that there was some talk of phasing it out and using an acetalyne mix, but I think folks complained that the mix wasn't hot enough.
Oxy-acetalyne burns together at about 5,500 degrees, so it's pretty darn hot.
The thing about gas welding is that if you can master it, using the torch and filler rod, you shouldn't have any problems moving over to the TIG machine, which is a GAGALLION volts of power sent through a pencil lead to weld the metal.
I'll try to get more images once the kids start to actually make something.
Anyways, I really wanted to show these off:

That's right fabrication fans!
A mill and a lathe!
Oh Boy!
When I first got into the shop, I drew a bead straight to them machines.
Visions of aluminum billet and curly strings of cut metal went dancing in my head along with dreams of little sprinkles of shiny dust falling to the ground.
I already looked up a Columbus tubing set and need to look for some drop outs, head tube and bottom bracket.
I can mitre the tubes on the mill and put the whole thing together with the TIG.
Unfortunately, none of the present instructors knows how to use them.
The mill and the lathe I mean.
I sense some kind of Flat Tire intervention here.
Overall, I'm really impressed with the shop.
In many ways, it's equipped better than the shop we had at university type school; they got more welding machines and they are in nicer condition.
I gotta hit up the Man Store and get me some steel stock so that I can try some of the stuff out!
Some aluminium billet would be nice too.
I just need to learn to draw a bead.


Big Oak said...

Good luck! That really looks like fun. I've always wanted to take a welding class, but keep forgetting to check the class schedules.

Google Alex Wetmore - if you haven't seen his blog, you should check it out. He's made some frames, and he's made some jigs for frames and forks that he sells.

I can see it now, Flat Tire Frames...

limom said...

I'll check the blog out!
Tell you the truth, without a frame jig, any frame I make would probably roll sideways.

Steve A said...

When I took auto body, we did lots of oxy acetylene welding. I wish I still had my equipment.


Steve A said...

And I think you are actually "laying down" a bead rather than either drawing, pushing, or pulling one.

John Romeo Alpha said...

Stack of dimes, some welds look like. I think you have the potential to be the Yoda of bicycle framemaking.

Mark said...

Is there a waiting list for flat tire frames already?

limom said...

Steve A., literary license.

JRA, not in this lifetime.

Mark, one list you do not want to be on.

What I may do is take an old frame I got sitting around here and take it apart.
Welding or brazing super thin tubing can't be easy.
I'm interested in seeing just how difficult it is.