Thursday, April 28, 2011

Joining Practice Part II

Just got back from evening class. Practiced Fillet and Lug Brazing some more. More pictures!

Here is some improvement on my lugging and fillet brazing. The above joint is a fake lug, the cylinder to box joint is fillet brazed. Although I improved my technique a lot, I had the problem of having that white build up on the edge of the brass. The white matter is zinc chloride or zinc oxide or something like that... It appears when the brass starts to heat up to a considerable degree; the higher the temperature, the more zinc that becomes exposed. Though the white patina can be easily washed off, zinc also comes out of the brass in the form of a toxic gas which is fairly unhealthy to breath. It probably is indicative of me over-heating the steel anyway, so I should back off on the torch in the future.
 I got a little torch crazy. Here are all the sample welds up to this point welded together more or less... The assignment was to do one hollow form using oxy-acetlyne welding--which I did, but decided to do a little brass work too. Gussy it up, y'know.
Here is a joint similar to what you'd see on the bottom bracket of the bicycle. Fillet again.
Too much heat...
Hopefully my lug work will clean up to this point, as the clear-coat on my fixed gear reveals. FYI I did not do this, some poor factory worker in Japan during the late 70's did.
You can see the copper coming to the surface of the brass on part of these drop outs. I spy with my little eye some hidden Dura Ace... I also apologize for the fuzzy photo quality, I haven't really figured out focus on my camera yet.
The quintessential lug.

Joining Practice

Me and the 2 people working on frame building all practiced our respective joining techniques in the metal shop today. I was working with brazed lugging while the other two worked on fillet brazing and TIG welding. I also tried oxy-acetlyne welding today as part of my metalworking homework. Here are some photos.

This is a pretty poor attempt at lugging. Brass, a softer metal than steel with a higher melting point, moves toward the hottest part of the steel. The trick is to heat up the part of the steel you want the brass to move to while also pushing the brass towards that specified area. This means a bit of going back and forth between points while keeping the brass on the track you want it. I learned all of this as I was going along, so hopefully future attempts won't be so dirty and sloppy...

A look at the inside... You would ultimately like to see the brass seeping out of the other end of the tubing, though I probably inserted the tube too far for the brass to travel. Either that, or I'm just bad at controlling the flow...
This is a oxy-acetlyne welded form that I made out of scrap 16 gauge sheet metal. Steel of course. I'm way better at oxy-acetlyne welding than brazing, but I guess I also have way more guidance and experience with it.
Scrap tubing donated by Bill Stevenson, a local frame builder here in Olympia, WA.
Fillet brazing. Depending on technique, the brass can really build up trying to weld the two tubes together. To get the desired aesthetic, it seemed smart to grind down the brass with a file or circular grinder.
Here is the result. Fillet brazing is considered inferior to TIG welding because you're more gluing two pieces of metal together with a different kind of metal rather than fusing them together. But both are plenty strong to withstand the loads bicycles take on for the most part. I'll go more into the benefits of certain joining techniques in a later post.
TIG welding in action.
TIG welding. Most steel frames that you encounter today are joined though this method, such as Surly's or Somas. Only curmudgeonly dated cranks bother with brazing these days; such as myself. There are reason though, promise!
Fillet brazing and TIG welding in one dummy frame.

Wednesday, April 27, 2011

Getting Started

I'm not entirely sure how to start one of these things, seeing how I haven't had a blog since I was in middle school... As such, I'll default to talking about who I am and what you can expect to read about here.

I'm a senior student enrolled in my last quarter at the Evergreen State College in Olympia, WA. What I've studied up to this point is pretty irrelevant seeing how it has no relationship to the work I'm doing nowadays. Instead, I am working in the metals and wood shops on campus learning different crafts. Much of my time is spent working at the Evergreen Bike Shop--a D.I.Y. space for working on bicycles. I'm usually split between mechanical stuff and administrative work, so I don't know how much time I'll have for posting in this, but I thought It'd be helpful for myself...

(Cog)nitive Dissonance--besides being a catchy sorta-pun--describes my relationship with bicycles. I still consider myself novice in regards of the material I will be approaching, and am constantly struggling with the often contradicting facets of information that I come across regarding bicycle design and 'culture' (excuse me bike snob.) So a lot of what I'll write about will be my experience with these different schools of thought applied in real life scenarios and what my findings are.

Besides that, I'll write about a few different bike topics: taller frames and bike fit, PNW cycling, 'nuovo-retro' design, old french bikes, brazing techniques, frame building, off-roading, bicycle co-ops, competition vs. commuter cycling, and other stuff I guesssss. It'll get more exciting as it develops, promise.


Anywhos, all that aside here is a sneak peak of what my design will be: