Bilaminate frame construction - "Alex Singer" style?
 

I can understand the process to make it this way:

https://cimg9.ibsrv.net/gimg/bikefor...162afa673d.jpg


But am trying to figure out the order of fabrication in this method:


https://cimg9.ibsrv.net/gimg/bikefor...2659f8883a.jpg

At first I figured one would just brass braze the "lug", then silver the tubes in, then I realized there would be no way to get any decent penetration into the lug. So then I figured silver in the lugs, mitered to match the TT and DT, then fillet braze with brass. But brass temps would melt the silver. So now I'm thinking you brass braze the lug onto the TT and DT, either pre-mitered, or mitered together with the tubes, then fillet braze the sub-assembly onto the head tube.

Anyone try this before?

I've done a few of the second version, not for full frame building but tools and play things. Flow brassed a sleeve with a lug like shore line cut on the tube end, miter sleeve and tube like a tube gets and fillet against the second joining tube. Use brass/bronze for both steps. Andy

Thanks Andy, that's the only way I could think that it would absolutely work. Now I've got to go practice some old school brass/bronze lug brazing. I'm guessing the best way to do this would be to pre-miter the "lug" part and braze it onto the tube with excess, so I could use the excess tube to draw the filler in, then trim it back to the lug miter. I think you wrote the same thing using different words...

Follow up question: 1" tubing fits inside 1-1/8" 0.58", and I've made a few scratch lugs that way, but they're pretty thick. I'm guessing the thing to do is turn down a 1-1/8" tube to thin it down first. Looking for someone with a lathe to do that.

I have read of both centerless grinding and simple turning down as thinning methods. Of course there's always filing:) Andy (who has a set of self made lugs in process and they will be for a long time)

I could turn some down for you

Herbie Helm had a beautiful frame at the Richmond NAHBS. He silver brazed the "lugs" onto the tubes and then brass brazed the tubes together. So you certainly could brass braze both.

I turn my seat cluster sleeves and other bi-lam sleeves down to around .045" wall thickness from .058". The thicker look is just a bit too chunky for my eye.

Agreed.

I've done a few scratch lugs with .058", and did a lot of filing and sanding to thin them out after brazing. It's a lot of careful work, would rather start with thinner material.