This article is part of a series I am writing about my experience taking a bicycle frame building class from master framebuilder Doug Fattic in Niles, Michigan.
Andrew brazes his rear drop outs with brass. The intense heat for this brazing requires dark glasses.
I’m beginning to see the light at the end of the tunnel on my frame. The last few days have been great with parts of my frame now resembling a bicycle and my brazing skills gradually improving with a few set backs.
On Sunday, we put together our chain stays with our drop outs and were this introduced to brass brazing. Brass is used in fillet brazing (i.e., luggeless) and in instances where there are gaps to be filled that are too large for silver to work. All of us are using tabbed rear drop outs (instead of plug types) which means there is a huge gap between the tab insert and the tube side walls. Enter brass.
Much like when I began first brazing last week, I was feeling a little intimidated by brass brazing. Brass has a higher melting temperature than silver requiring the metal to reach a cherry red color in heating. Brass is much more molten than silver in consistancy once applied allowing the piling on of material. Despite the cherry red heat, I actually enjoyed brazing with brass better.
In addition to an introduction to brass, I was also able to finish my fork by brazing the fork blades to the crown. This was immensely satisfying as I now have a fully functional part of a bike. With my fork and chain stays done, Doug instructed me to prep the front triangle of the frame for brazing in Monday.
The front triangle of my frame spot brazed and ready for alignment.
By supper time Sunday, I was quite a bit ahead of the rest of the class in completion. This led to a little over confidence on my part. I decided after dinner to go back to the workshop to do a little touch up braze on my fork. I was a little irritated to see Doug there as I really thought I was ready to braze unsupervised. It turns out it was a good thing he was there. All the brass brazing must have scrambled my mind as I made a mess with my silver. Doug saved the day, and I learned the first rule of framebuilding is humility.
On Monday, things really began coming together. After finalizing the front triangle of the frame, I spot brazed the whole thing and spent what seemed like an eternity with the frame on the alignment table. Bicycle frames need to be properly aligned or ride quality and frame strength are compromised. The alignment table, a table top machined to be extremely flat, aids in this effort. Before fully brazing the joints, my frame was bolted on the table and I spent quiet a bit of time checking the tubes with a surface gauge and making small adjustments. Once the frame is properly adjusted, the full brazing begins.
I don’t know if this stuff is sinking in or the beer I had with dinner loosened me up, but I attempted another unsupervised brazing after dinner, and it went very well, without a hitch. I may just be on to something. Or the frame building gods may strike me down tomorrow for my hubris. I guess we’ll see.
Read the next post in the series, Day 8-10, Austin, we have a bicycle frame.
on Dec 22nd, 2008 at 2:14 pm
[...] Read the previous post in the series, Day 6 & 7, Things coming together. addthis_url = ‘http%3A%2F%2Faustinbikeblog.org%2F2008%2F12%2F12%2Fdoug-fattic-framebuilding-class-update-day-8-10%2F’; addthis_title = ‘Doug+Fattic+Framebuilding+Class+Update%3A+Day+8-10%2C+Austin%2C+we+have+a+bicycle+frame’; addthis_pub = ”; Email or Print This Post: [...]
on Apr 1st, 2010 at 6:03 am
The blog is quite interesting as well as magnificent, as it illustrates many important aspects of how brazing could be done more precisely.
on Apr 16th, 2010 at 5:16 am
Oh nice post!!! The tips discussed about brazing process have been quite noteworthy. Would like to congradulate the author.