Yamaguchi Framebuilding School - Day 9

Today was the penultimate day of the framebuilding class, and oh my there is still a lot of work to do! The morning was spent brazing small pieces to the frame, namely the rear brake bridge, the water bottle holder lugs, and the shift/brake cable holders. Of these, the brake bridge was the most difficult part. Both ends were mitered to fit the angled seat stays, but with two extra constraints. First, the bridge must be exactly the correct length, in order to position the brake mounting hole 355mm from the rear wheel axis. Second, that mounting hole must be precisely in the middle of the bridge! It took me a dozen test fits to get the bridge exactly right. After that, it was fluxed, tacked, welded, and fillet brazed in place.

In addition to the brake bridge, a few small parts were brazed on for the water bottle and cables. These small parts are pre-made from cast steel, and are silver-brazed to the frame. This is a lower-temperature brazing which allows these parts to be easily removed or replaced if damaged at a later date. Positioning the cable holders was tricky! But brazing them in place was a matter of minutes.

Over lunch, the frame was immersed in a tank of heated water in order to dissolve all remaining flux, both on the inside and outside of the frame tubes. The fork and other small components were de-fluxed in smaller containers, also using hot water.

After lunch, I started finishing work on the front fork and frame. Small curved “riffler” files were used to clean up the lug welds on the fork. These files are super handy, and are a staple of diemaker’s toolboxes. They’re also astoundingly expensive - a quality set on McMaster costs something above $200! I’ll just get a set of cheap knock-offs from the usual internet clearinghouses. A wire brush was used to burnish out scratch marks, and bring the steel to a higher shine.

Detailing on the frame, for today, mainly constituted trimming the seatpost and adding a little style feature. This was done, as per normal, using nothing but flat and half-round files! A bit time consuming, but it adds a nice personalized touch to the frame.

Tomorrow is the last day! Facing and reaming of critical surfaces, final alignment, and more finishing tasks will make it a busy day!