YFBS: Day 5 - Forked and Tacked

Over the next few days, I will be talking about my time at the Yamaguchi Frame Building School.  The first day can be found here.  

Class continued immediately where it left off yesterday, finishing the miter on the top tube and making sure that it matched the seat and head tube.  Carefully measuring the angles, Mr. Yamaguchi showed me how to line up the tubes center to center and check the final measurement.  530mm exactly - my hard work had paid off.  

This intricate setup may seem overly complicated, but every piece is necessary.
Next up was prepping the lugs for the headtube.  Since it's optimal to experience both lugged and fillet brazing, my frame will be made with a lugged headtube and fillet brazed seat and bottom bracket joints.  Sanding the lugs was tedious, as great care has to be taken to ensure that both the insides, outsides, and luglines are all properly sanded and there are no bumps or rough edges.  Many lugs are also stamped with either a maker or an angle number, and it's sometimes undesirable to have that showing, so that must be sanded as well.  

Sanded and shiny!
Sanding the lugs took quite a bit of time, but it did allow me to shape certain areas a bit.  Pointy, crisp lugs are desired by some builders, so I filed down the points a bit to get the same affect on my lugs, careful not to stab myself more than once on the sharp points.  

It's the little things: this is a muffler expander, or as Mr. Yamaguchi uses it - a lug holder.  Creativity and versatility is a big part of Mr. Yamaguchi's method, and he's made most of his own tools or has found clever uses, like this one.
My previously brazed bottom bracket also had to be cleaned up so that the downtube would fit against it snugly, so there was more filing and sanding to be done.  In the meantime, Mr. Yamaguchi prepped the alignment table and the tacking jig so that tacking could begin.  Since there are only two areas to tack and three students, I got to move on to my fork crown while my classmates started tacking their frames.

All cleaned and filed.
A little bit of steer tube is left over, which will be filed off later.  I almost have a fork!
The fork crown requires silver brazing, which is slightly different (and a whole lot easier) than bronze brazing.  First, the steer tube and the fork crown had to be sanded and prepped.  The fork crown was exactly like the lugs, except a dremmel was used to reach the inner, less accessible areas.  Mr. Yamaguchi told me that a frame can almost be made entirely without electricity, but there are certain times when it's nice to have tools to help.  I'm glad that we're being shown minimal use of the electric tools though, as the basic understanding and technique of everything is far more valuable.

Jig one, set up with one set of frame angles.  Mr. Yamaguchi made this particular jig.
I busted out the drill press again to drill holes in the steer tube which lined up with the inside of the fork crown.  This, similar to the bottom bracket, is for air and heat to escape while brazing.  Everything was cleaned with acetone and prepped with lots of silver flux (silver flux is white, while bronze is blue) and tacked the fork crown to the steer tube.  Silver melts at a much lower temperature, and is much thinner, getting into tiny crack in between the lugs quite nicely.  It's not at strong as bronze though, which is why it's not commonly used for fillet brazing.

If you look carefully, you can see the holes that I drilled.
Flipping the fork upside down and using a spare seat tube to hold it, Mr. Yamaguchi installed the fork in a stand and showed me how to braze silver.  "Silver likes gravity," he told me, lighting the torch, "so we braze upside down and use heat and gravity to get it to do what we want."  With precise movements he started to braze the silver using a method similar to that of internal brazing: silver was melted on top, where the steer tube meets the bottom of the fork crown, and then was pulled through the lugs with the torch, where you could see it oozing out of the bottom.  He handed me the torch and let me finish the rest.

See the silver on the bottom?  That was pulled through using nothing but heat and gravity.  This technique makes the fork quite strong.
Once I was done with the fork crown, a jig had opened up, and I could begin my final mitering and tacking.  At this point I still needed to cut my seat tube and miter my downtube.  I started with the seat tube, leaving a little extra material at the top so that I could miter in some details later.  I set up the down tube, made my centerlines, and started mitering.  The last tube is the most difficult, because it has to lock in against the bottom bracket and head tube while still matching up to the previously made centerlines.  While measuring where I was at (and noting I had about 2.5 millimeters to go) class was suddenly over, and I went to clean up my work station.

The alignment table jig, all done up to my measurements and ready to go!
My classmate's fully tacked frame.  It's starting to look like a bike!
While cleaning, Mr. Yamaguchi was asking me about what movies I'd worked on, and he ended up mentioning that he had worked for a game company.  "Small company in Seattle," he said, "called Valve."  My jaw dropped and I started asking him all about it.  Turns out, Valve had asked him to design and build a bike for Day of Defeat (or possibly Counter Strike), and in return had made his website.  He pulled out the original plans and pointed to the bike, which was sitting in the back yard.  The video game lover in me was jumping for joy at this point. "They gave me a Steam account with 2000 games, but I don't play so much," he chuckled.  

With the Half Life insignia and everything!!
In all of it's gamer glory.
I also took the time to ask him about my broken Takhion fork, and if it was repairable, "Ahh, yes, I made one once." He pulled out one of his many photo albums and turned to a page with a familiar looking lo pro design.  "I took photos of the process as well, I'll have to find them.  But it can be brazed and it will be safe enough to ride, either on the track or on the road!"  I graciously thanked him and wished him a good evening, then walked back to my hotel in high spirits.

More of the shop.  So much cool stuff everywhere you look.
Looks like a previous student had some Photoshop skills.
Tomorrow, I get to build a stem!  

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