20130409

YFBS: Day 2 - Brazing the in Snow

For the next few days, I will be detailing my adventures at the Yamaguchi Frame Building School.  The first entry can be found here.


Track dropouts on an in-progress frame.  <3
After dreaming about frame geometry and angles, I awoke to a frigid morning ready to begin getting hands on at the shop.  I bundled up and braved the cold (my Californian might be slightly showing here) and trekked to class, where we were met with the first task of the day: learning to cut tubes.

My station.
There are many machines capable of cutting tubes, all of which are present in Mr. Yamaguchi's shop.  But you have to crawl before you can walk, and we must first learn how to do things the old fashioned way.  Each of us was assigned a station, complete with a multitude of tools for whatever we may need, and then we were given a demonstration on tube cutting.  Working effortlessly, Mr. Yamaguchi showed us how to put the tube in the vice, level everything, cut tubes using a hacksaw, explained the proper way to cut, what type of blade we'd need (HSS) and how many teeth it should have (32).  Then it was our turn.


Practice rings!  It takes time to get the technique right.
Practice was done by cutting off small pieces of the tube until our cuts were straight and true.  I worked on placing the tube in the tube holders, then leveling it on the vice, and using masking tape to mark where I wanted to cut.  My first cut was way off, slanted too far forward.  I kept cutting, correcting my stance and technique after each cut, and slowly improved.  It was sometime during my attempts that it began to snow, and my classmates and I escaped to get some coffee and lunch before making the final head tube cut.


Quite a lovely snowy day!
Returning from lunch, we all had to cut our head tubes and move on to the next lesson.  Mr. Yamaguchi stresses to always cut a bit longer, because you can always correct for it, so my 120mm head tube was cut at 123mm.  Or, it was supposed to be - I managed to cut it around 124.  Not bad for my first head tube!


The view out of my station's window.  Snow!
Next was the beginning of the brazing lesson - brazing isn't a complicated process in concept, but getting the rhythm and all of the steps down is difficult. First I was shown how to sand the tube - first straight, then at 45 degree alternating angles, creating a cross hatch pattern.  This allows for the bronze to stick better.  Mr. Yamaguchi went on to explain the different types of flux, brazing, what is used when, and how the fuel and oxygen lines are hooked up. Then we were instructed to put our safety glasses on.


The many flavors of flux.
Bronze and silver brazing.
The flame diagram and PSI for Oxygen and Acetylene.
With precision and intuition, Mr. Yamaguchi turned on the fuel and ignited it, then adjusted the oxygen to get the perfect neutral flame in one fell swoop.  He demonstrated a flame that is too hot (too much oxygen) and a flame that won't burn well (too much fuel) and what they looked like.  He shut off the fuel with a loud POP that made us all jump - something that happens sometimes when the fuel is either shut off too fast or the mechanism needs to be cleaned.


Red is fuel, green is oxygen.
Matt shows off his igniter skills.
I prepped the sanded tubes and bronze with acetone, and then applied the flux.  Cautiously turning on the fuel and grabbing the igniter, I managed to get a fairly decent looking neutral flame.  Now it was time to braze towers.


To prevent contamination after cleaning, a coffee can is used to store the brazing while it's waiting to be used.
Mr. Yamaguchi made the towers look incredibly easy.  The fact is, the concept is easy, but getting everything in sync is what is hard, and comes with years of practice and a feel for the art.  Before I knew it, hours had passed and I had made a few (pathetic) towers that fell over quickly.  It's a good thing we're continuing this practice tomorrow, because it was only near the end of the day that I felt like I really got the rhythm.


Mr. Yamaguchi's tower.  He made it look much easier than it is.
Previous students' towers.  Much better than mine!
I walked home in a rather surreal winter wonderland, looking forward to perfecting my brazing tomorrow.


Snow!


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