now it's sam hall's turn to be right

damn, i have some good commenters on this thing and it's a week old.
thanks, sam. glad i could help.
you're right about the joining, and it brings up a good point: there's nothing like good brazing.
i don't have access to brazing equipment yet, but if i did i'd spend way more time learning to braze and perfecting my technique and way less time doing math. all in good time. Talbot has a big chapter all about brazing that i'm looking forward to.
my thought about Little Fish was that better tubing might have prevented such a break. better brazing would have been better still.
on the other hand, i bet Little Fish thought she was pretty good at brazing and thought that joint was solid. it was pretty solid; she rode 10,000 km on it. she's pretty meticulous about everything else, least as far as i could tell, so i wouldn't have thought she'd make a mistake like that.
it's the worst-case-scenario part of me that says, "What if i braze a joint, and it looks great but has a hidden flaw, like Little Fish's?" in that situation, i'd think stronger tubing would help. might even prevent a bad joint from turning into a break.
it's a hypothetical, a pretty remote one that i don't plan to encounter because i plan to do enough brazing to get damn good at brazing by the time i put this thing together.
on the other other other hand, there's steels available today that weren't around when Talbot was building, and i'd like to take advantage, especially since the new stuff is considerably stronger and not a whole lot more expensive.

reading this Talbot book is great. a very old-school approach. there's no discussion of anything but lugged steel. simple guide to fitting that seems like it would work well.
it goes into some cool math regarding fit and design. there's enough for dorks like me, but it never gets in the way.
next step may be some drafting.

last day of class this week...more research this weekend at LOC.

Welding Supply has cheaper silver brazing rods than Henry James...have to check if HJ's is better.
Posted

1 comment:

Anonymous said...

Call me Bingo Smith. I'm your first anonymous. I don't know the rude bastard was who left the second message.

I wouldn't comment except to help.

You're welcome to start with whatever tubing you like - just like I did.

Usually the more expensive tubing has thinner walls - which isn't likely what you want for a touring bike (and it's harder to braze).

The broken Little Fish frame was roundly and soundly diagnosed on the list. The problem was a bad braze - either overheated (burning out the flux) or not clean enough. From what I know of Suzy, I'd suggest the first. But, in any case, a change of tubing wouldn't have solved the problem.

Cheaper can be better, or not. Two things to consider: a) does the cheap source offer as good or better a product; b) can the cheap source provide support to your questions about using the product in the context of bike building.

The latter is important. Few brazers work with as thin a tubes as framebuilders. We are on the edges of technology, believe it or not. Hank can be a great resource.

However, when it comes to silver, you would do well to catch up with Fred Parr. Partly because of his expertise, partly because he offers the best silver and fluxes around. Check out his site at www-dot-cycledesign-dot-org. Then give him a call. Treat him right and you'll have a great resource.

Good Luck

Bingo

4/08/2006 9:51 PM

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