Re: [CR] 71 Colnago

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From: "John" <torup@sbcglobal.net>
Date: Wed, 16 Jun 2010 09:40:16 -0700
To: classicrendezvous@bikelist.org
Subject: Re: [CR] 71 Colnago


Garland-

In regard to what to remove to return to original, the water bottle braze ons are probably the most effort in thinking and process. Only pass through internal top tube cable routing is more effort.

Silver brazing a bolt in and filing it smooth with the circumference of the tube may not work, the primary contact area for the added boss may be the flange just beyond the tube. If so, there would only be a butt joint there, not much contact area. The way I have seen it done is:

A plain finish roofing nail silvered in, held by the nail shank, while brazing and then cut off after. (I always thought a small washer might help here too to fill the hole)

A section of tube applied to the inside, using gravity to help position the reinforcement. (watch for drips)

I think an overlap is best here.

Or, just leave them, no more heat. A case can be made for that.

When I have removed cable guides on a top tube I threaded a section of tie wire through them, heating the braze on only and let the heat migrate to the tube through the brazing, always pulling as I heat, minimal reheat that way, clean up with a file.