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Did I fork this up?

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Did I fork this up?

Old 10-17-21, 03:02 PM
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mrv 
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Did I fork this up?

Iíve been working on a bodge project to change a cantilever brake frame set from 700c to 650b. I removed the canti bosses on the fork. I had some filing to do to clean things up.
i got a bit toooo aggressive/careless and gouged the fork itself.
Almost 1mm deep, about 10mm long.
Let me know if Iíve probably made this 30 year old fork a little less safe, or significantly more less safe.





thanks. (maybe I should stick with just cycling to the coffee shopÖÖ&#128530
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Old 10-17-21, 03:34 PM
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Fork legs are usually pretty thick. Just drop a bit of weld in there and sand it all flush and nobody will ever know. Very unlikely to cause a failure.
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Old 10-17-21, 07:53 PM
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Those bosses were tig welded on you are also seeing weld under cutting common with tig joints.
i would not worry too much. As stated above the tubes are thick.
i have removed and moved hundreds of those on mis-spec-ed forks from QBP. They had a thing about ordering them at the wrong height. I found micro fractures around the bosses from the factory over heating while brazing as well as what you are seeing with the weld under cutting.
If the new bosses will be low enough fill with silver. Your bosses can be done in silver too.
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Old 10-17-21, 08:13 PM
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Originally Posted by pwyg;[url=tel:22273644
22273644[/url]]Those bosses were tig welded on you are also seeing weld under cutting common with tig joints.

Your bosses can be done in silver too.
TIG makes sense - I tried to melt the bosses off like I did on the test triangle, and it wasnít happening. So I went at them with a hack saw. I thought about using this as an excuse to buy a small grinder.
My plan is to braze silver for the new bosses.
Iíve been shaping the new bosses a bit on my bench grinder to make sure the contours match.
Thanks for the reply.
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Old 10-18-21, 04:03 AM
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I recommend buying a nice file and going more slowly next time. Hacksaw only what you can see and leave a little bit to file off.
If it wasn't a cheap fork, you definitely would have ruined it. A good fork blade isn't much thicker than that. There is no reason to leave yourself wondering if it's okay or not. The question will come back to you when you are riding at high speed down a mountain.
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Old 10-18-21, 06:41 AM
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Originally Posted by unterhausen View Post
I recommend buying a nice file and going more slowly next time. Hacksaw only what you can see and leave a little bit to file off.
If it wasn't a cheap fork, you definitely would have ruined it. A good fork blade isn't much thicker than that. There is no reason to leave yourself wondering if it's okay or not. The question will come back to you when you are riding at high speed down a mountain.
I had sawed off as much as I safely could, being careful not to let the blade steer itself into the fork blade. I "think" I was OK there.
I inherited about 100 lbs of files from my dad, a millwright. So I was working my way to the finer files.
I was using a very aggressive rasp file to get the boss remnants close the the for blade - and just was not being careful.
The whole '91 Schwinn CrossCut frameset was $40. I'm about 55% sure this is a Chinese frameset. So if I foul the whole thing up the lesson cost of the lesson is not too bad. (it's not going to start getting financially expensive until I start building the wheels.....)
Thanks for the reply.
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Old 10-18-21, 08:27 AM
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Unfortunately the cost of a failure of a structural part that is supported at one end only (think about this, every other tube in a frame is attached at two ends, but the fork) might be measured by the medical industry... Andy
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