Well, internet statistics seem to indicate that these frame building posts are the least interesting. Even the spam bots are ignoring them. However, this is the last full day of class, the last day we’re going to have torches running, and the (exciting) conclusion to this story. So if you don’t mind I’ll press on and finish it.
Thursday: When things went wrong
As of Thursday, with only a day and a half left to work, it seemed inconceivable that we’d have rideable bikes. True, the structural components were in place and aligned, but what about things like brakes, cable guides, and for godsake what about water bottles!? Most everyone had torches and drills running the whole day in order to finish before Friday.
Case of the Troublesome Bridge
I was a little ahead, but I still had lots to do. And a problem. The seat stay bridge that I measured and mitred late the day before was too low to accommodate a 650B wheel, even without fenders — although it would ride fine without a tire. I hadn’t taken into account the seat stay supports. I could leave out the supports, but it would look more like a production bike, and I didn’t want that. They were only 1.5mm thick, but there is one on either side and 3mm on a 7 degree angle changes the position in a not-so-insignificant way. On the plus side, the bridge was too long, not too short, and it’s easier to remove material than to add it. So back in the vertical mill it went. (I was advised it wasn’t a job for hand-mitring with so little time left as any mistake would result in even more time lost.) Luckily, the hole I drilled for the braze-on to mount the fender was dead center, so the mill didn’t have to be reset between shaving off the two sides. Dan, who helped me with it on Wednesday reran it for me and it fit perfectly.
As it turns out “perfect” is a relative term. It’s still too low to take fenders on a 650B rim with a 42mm tire. This is something I would have noticed if I a) was working at my own pace and b) had test fit the wheel I wanted to use. The fault was in my measurements, I hadn’t taken into consideration the bridge’s tube diameter, nor the height of the lip on the braze-on boss to which the fender is attached, which is an additional 2mm. It doesn’t sound like much, but 2mm here, 4mm there and suddenly the 14mm fender clearance I had budgeted was gone.
The chain stay bridge didn’t have this problem because its placement was by in large determined by the ovalized portion of the stay tubes. The bridge was much easier to mitre so to mate with the round portion of the stays rather than the oval portions.
Botched Bottle Bosses
After brazing the bridges, I realized there wasn’t time to clean up and bask in the glory of what I’d done. Nope. On to the next part. As soon as I shut off my torch, I spun around to the jig cabinet and grabbed the water bottle boss jig. I quickly placed the two dummy bottle cages thinking to myself, lower is better. I wondered why people didn’t really lower them, so I placed the seat tube bottle really low. The school has an angle drill that makes quick work of these holes. I cleaned up the holes with a deburring tool, file and emery cloth and brazed on four bosses. Boom!
What next? I looked into my baseball cap where I set aside all of the braze-ons I’d need for this bike, and grabbed the chain hanger. This one I didn’t use a jig, I just balanced it on the seat stay hoping that the flux wouldn’t cause it to float onto the ground. It worked but I wouldn’t do this again. Then I grabbed a cable guide jig and brazed three of those on, two on the underside of top tube for the rear brake, and one on the drive side chain stay for the rear derailleur.
The Cantilever Controversy
Since the frame was in the stand still, I decided to braze the cantilever brake bosses next. This is where things start getting messy. A confluence of measuring mistakes caused these to be misplaced on the frame and eventually the fork. I’ll admit to some of those errors, but my biggest error was, again, not test fitting the placement with a wheel installed. I grabbed the brazing jig for this task and stuck those suckers on good and tight.
At this point, the frame had about four brazings worth of dried flux caked on it, slowly turning to glass. I decided that removal was something I could do the next day or at home and started to mount the braze-ons to the fork. The jig for this is probably the least useful in my opinion. It has registration marks for distance from the hub, but doesn’t take into consideration fork rake. My fork rake is extreme by common standards, roughly 68mm, which compounds the problem for this jig. It also has a problem applying uniform pressure to the left and right braze-ons at the same time. With the flux all up in there, it’s hard to see the gaps. This began my endeavour to learning to fillet braze with silver… pretty much a waste of time and silver.
These mistake in the placement of these four crucial parts wouldn’t become apparent until I tried to build the bike four days later.
The shop was fuming hot this day and a little cross breeze from the open doors on either end was little relief. So I was actually glad to hop back on my bike and ride 100 minute commute back home. On that ride, I looked down at my bottom bracket as I often do. The front derailleur kept grabbing my attention for some reason. After a while, I realized it was located on this bike, right where I placed the water bottle bosses on my new frame. Doh! That’s why they don’t put them so low, I thought to myself.
Friday: Making Things Right, Sort of
I let Joseph know what I’d done with the bottle bosses and apparently the no-torch-rule-on-Friday is more of a guideline. I drilled a third hole above and inline with the other two and quickly brazed on another boss.
The rest of the day was spent removing most of the flux, facing the head tube, reaming the seat tube, adding threads to the steerer tube, and retapping and facing the bottom bracket. This was only a half-day, but by far the most physical. When we’d all finished, we had our pictures taken, spent some time asking questions about the business ends of frame building, and were given our certificates and a handshake.
On Saturday I tried to build the bike, well, just put the rims on and noticed the front canti bosses were too high. Then I noticed the rear ones were waaaay too high, above the rim and almost high enough to install Paul Racers. I pulled the rim off and spent a few hours removing every molecule of flux with metal tools and emery cloth. When the frame is just steel, silver and brass, it’s quite a beautiful thing, even if the brazing is done by an absolute beginner.
On Sunday, I shot an email to Joseph asking him if he’d move those bosses for me. In the end, we agreed on Tuesday afternoon and he was kind enough to do that for me for just the price of the silver. The next day I tried to paint it with some primer and the only color the local one-stop-shop had. It was a blue mess, literally. For the price of getting it powder coated by a professional, trying to hand paint it isn’t work the the time, expense and sticky mess to me. My brother dropped it off at his powder painter, Zollwerks in Dundee, OR on Thursday who turned it around in just a day. Fine work.
I got the frame back around 4 PM on Friday and had to catch a train the next morning at 6 AM. I literally threw the bike together, mostly, the rest in a suitcase and headed for Seattle. I’m waiting for the last parts to arrive today and will take it on a brief ride this evening and maybe get some beauty shots of it.
All in all, my experience at the United Bicycle Institute was extremely rewarding. I feel they give the dedicated student enough knowledge and experience to build bikes on their own, and enough resources to get help when they need it. I would do it again. And many students do take the class again. I find myself less interested in TIG or Ti classes now, but could see returning to the chromoly brazing class to concentrate on fillet brazing next time.