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-   -   Brazing; Minimal paint removal for repair? (https://www.bikeforums.net/framebuilders/1163172-brazing-minimal-paint-removal-repair.html)

Medic Zero 12-30-18 08:09 PM

Brazing; Minimal paint removal for repair?
 
.

Just like the title says. Need to do a frame repair (drop-out) and might add some hourglass eyelets on the front fork at the same time.
Bike has a sentimental custom paint job that I'd like to preserve as much as possible. Will be repainting with a sort of two-tone in the areas where work is done.

I'm looking for a rough ballpark; 3 inches? 6 inches? 9? a foot?


Also, is it okay if the BB and headset are still in the bike when doing these repairs, are do they need to be removed? Other than the FD, all the rest of the components will be removed.


Thanks!

.

Andrew R Stewart 12-30-18 08:59 PM

IMO if you're good a couple of inches past the braze on or drop out is all you need to strip before brazing. This will grow about another inch with finishing. If you're less skilled that add a couple more inches. Heat Sink Paste or wet rags can limit the heat travel up the stays during take apart (which is hotter then the rebrazing is). So for the drop out expect a min of 3" of each stay needing painting and 6" of the blades with a mid mounted boss.

I would strongly suggest a complete take apart of all components. Makes handling, torch aiming mistakes, paint spray things much more straight forward and less mistake prone. Also makes positioning for/during brazing less involved. Ever done any floor refinishing? It's a lot easier if the furniture is moved out of the room. Andy

Specifically to the BB, yes remove it so you can soak out the flux from inside the chain stay.

Medic Zero 01-04-19 05:53 AM


Originally Posted by Andrew R Stewart (Post 20725187)
IMO if you're good a couple of inches past the braze on or drop out is all you need to strip before brazing. This will grow about another inch with finishing. If you're less skilled that add a couple more inches. Heat Sink Paste or wet rags can limit the heat travel up the stays during take apart (which is hotter then the rebrazing is). So for the drop out expect a min of 3" of each stay needing painting and 6" of the blades with a mid mounted boss.

I would strongly suggest a complete take apart of all components. Makes handling, torch aiming mistakes, paint spray things much more straight forward and less mistake prone. Also makes positioning for/during brazing less involved. Ever done any floor refinishing? It's a lot easier if the furniture is moved out of the room. Andy

Specifically to the BB, yes remove it so you can soak out the flux from inside the chain stay.


Perfect.

Thanks so much!




.

unterhausen 01-04-19 10:06 AM

I usually just burn off the old paint for 3-4" with the torch, much easier to clean the tubes that way. Never thought about using wet rags to limit the heated zone, that's a good idea.

Andrew R Stewart 01-04-19 11:19 AM

https://www.brownells.com/gunsmith-t...nt=083-012-100

I have used a similar clay like paste as this is before with very good results. The stuff I used would dry out during brazing and could be reconstituted with water. But in my many moves and doing less repairs then when I started I lost my stuff. Andy.

unterhausen 01-04-19 08:00 PM

I lost my stuff a long time ago


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