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Adding Cantilever posts to a fork

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Adding Cantilever posts to a fork

Old 03-13-20, 02:42 PM
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Tandem Tom
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Adding Cantilever posts to a fork

Over on the Google 650b group someone was asking about the above. I have in the back of my mind to do this on my Schwinn Super le Tour. But I have a replacement fork that is chrome. What is involved in the brazing process?
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Old 03-13-20, 03:03 PM
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The chrome should be removed from the HAZ to allow the filler to bond to the steel of the blades and to prevent any bad fumes from forming (something about a chromium containing gas that causes death or cancer). This removal might be elector/chemical "dechroming" or abrasive. Andy
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Old 03-13-20, 03:38 PM
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Thanks Andy! Maybe I will rig up an exhaust fan or do it in front of my spray booth.
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Old 03-13-20, 05:25 PM
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Tom you need to remove the chrome otherwise the boss might break off because it is bonded to the chrome which can break off of the steel. In other words if you don't remove the chrome, you are relying on the strength of how well the chrome is connected to the steel and not necessarily on how good of a brazing job you did. And of course when you heat it up to braze you lessen that bond. Chrome as you know comes in different qualities of application. Some flake off easily while others with nickel and and copper underneath are much stronger.
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Old 03-13-20, 06:03 PM
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Originally Posted by Tandem Tom View Post
Thanks Andy! Maybe I will rig up an exhaust fan or do it in front of my spray booth.
That should be fine. I'm no expert but from what I've read, hexavalent chromium ("chrome 6") is mostly a problem with arc-welding. Brazing temps being so much lower, I personally have no problem with only removing chrome right where the braze filler needs to wet out. Just don't sue me if you die, OK? I use abrasive to remove the chrome locally.

I have put canti bosses on lightweight blades many times. The flex is perceptible, but not a problem IMHO. Add a brake booster plate in front of the brake if you're worried about it; the better ones really do work.

Mark B in Seattle
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Old 03-13-20, 06:11 PM
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No lawsuit. Promise!
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