Downtube replacement questions

General Discussion
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Hi all, I’m replacing 34.9 mm Columbus Life downtube on a lugged frame. I used heat to remove the old tube from the BB and HT lug. After thoroughly cleaning the HT lug, there is a small amount of silver pooled inside the lug where the lug meets the HT. I assume this is going to prevent the mitered DT from having a tight fit against the HT, so I’m trying to figure out my best path forward. I can’t effectively remove the small amount of pooled silver with the files i have. Would it be feasible to try to fully seat the DT when the joint is heated and the extra bit of silver is melted? Any suggestions would be appreciated.

Also, the HT was already reamed and faced, but now I’m measuring some ovalization at the bottom of the HT after removing the old DT. Internal measurement is 33.4mm in the plane of the frame and 34.2mm perpendicular to the plane. Is this too far out to work with? Is there a way I can apply heat while brazing the new DT to correct this to some degree? Should I be thinking about replacing the HT altogether? Thanks in advance

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A repair is just that. You’re bringing a frame back to use, but it’s only new and made as well as possible once. If you’re absolutely certain the miter is the correct angle and the fit is decent (according to your own standards), clean it, flux it, and insert it. But only braze the tube to the area around it rather than drawing brazing material out onto the head tube. Some heat and flow will enable what’s already inside to mate the new tube to the existing joint so that it’s sound enough.

I realize it’s easier for me to explain this than it is to grasp and ultimately execute the task. But this is my recommendation.

You’ll need to machine the head tube interior afterwards regardless.

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Thanks Richard, your generosity with your time and expertise is greatly appreciated!