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Monday, October 24, 2011

When the moon is in the seventh house, or, how I learned to stop worrying and love frame alignment, part one.

Well, I was feeling all sparky and full of myself with my last two brazing efforts--attaching the articulated dropouts to the ends of the seat stays and chain stays, respectively. I mean, just look how pretty that articulated dropout looks up there--plenty of filler, minimal clean up. By the time I finished with the dropouts, I was convinced I had this process down.

And of course, you know where that kind of hubris inevitably leads. Next on the agenda was attaching the chain stays. Alignment is especially important here, since a wheel that is askew can create a wonky ride. I've been following this book by Marc-Andre Chimonas for guidance for my frame building adventure:

In it, the author suggests that rather than building a complicated jig for alignment, simply use an old wheel to get the chain stays properly aligned. Like this:

The problem I encountered when I tried this was that one of the lugs in the bottom bracket had some slop in it, and the chain stay would droop down, throwing the alignment of the wheel off. No matter what I tried, the wheel would slide cattywampus to the rest of the frame. I feared that if I tried tack brazing the whole shebang that way that tears would surely ensue.

Also, I didn't have an old wheel to use, and since heat is applied during brazing, Chimonas warns that this could ruin the wheel--something I wasn't too keen to have happen.

So I decided to build a simple jig to align the stays, instead of using the wheel. First I determined the length of the stays and cut them to be flush with the interior on the bottom bracket (shown here before cutting):

Then I attached two piece of angle iron and made sure they were flush with each other by attaching some aluminum bar stock at either end:

I aligned this with the frame:

Then I used a threaded rod and nuts that Will Cannings loaned me for a skewer and made sure the chain stays and dropouts were equidistance apart:


I measured the distance from the threaded rod to the bottom bracket on both sides to ensure that the chain stays would be the same length and alignment would be parallel. After all this, I fluxed everything up reeel guuud and tack brazed it:

After I tack brazed it, I took the jig off and put the wheel in and it looked like it all lined up just fine. So I removed the wheel and set to work brazing. Once I had finished, with everything cooled and the flux cleaned off, I put the wheel back in.

And it was cattywampus again.

Nevertheless, I am nothing if not resourceful, and I applied a little "cold setting" (the metal worker's term for what I would call "carpenterial persuasion") and got the wheel into what appears to be reasonable alignment:

It was late by this time, so I didn't put any measurements to it. If I'm not too knackered after work tonight, I'll do it then and make my report, in part two.

As an important aside, this process took me most of the day on Sunday, and involved a fair amount of head scratching, calculating, and minor frustrations. Even so, never once did a cuss word leave my lips. I hadn't realized that--nor its significance--until this morning as I was writing up this report. Normally during a project that involves lots of frustration, I curse like a sailor. However, I think that on this project, I am so engaged by it and having so much fun, that even the challenging parts give birth to joy rather than stress. Given this, I feel fairly certain I'll be building another frame in the future.

I'm going to build a better jig before I start next time, though.

3 comments:

  1. Cool! I love the idea that you're finding joy even in the frustrations. You clearly have what Richard and Molly call the "object manipulation gene." Have fun with it...

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  2. catawampus. New SAT word for the day, thanks.

    And I enjoy that you enjoy your project. Makes for a fun read... even if I don't always know what the hell (out of my own ignorance, really.) you're talking about.

    Hope your rain barrels (and yourself of course too) got to enjoy the rain today.

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  3. Hi there - found your blog and I'm also building out of the Chimonas book. Just curious how this project is going/finished up? Thanks for your thorough explanations and pictures!

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