Good afternoon,
I see with an endoscope camera that the solder joints of Columbus XCR tube connections have been 90% capillarily penetrated all around on the inside after the first soldering pass.
At 10%, I see no yellow solder seam.
I used 30% silver solder for the first soldering pass.
My question is: is it advisable to use liquid 56% solder for the first pass for better capillary penetration, and then 30% for the build-up?
met vr gr
Martin
I don’t know the liquidus temp for the 30% silver filler you have so don’t feel comfy giving a thumb’s up. Generally one wants the “tinning”/capillary filler to have a higher melt point than the follow up fillet filler does.
Was this joint your first brazing attempt? Did you practice with the 30% on a scrap piece first? Do you have the 56% already? If so can you experiment to find out? Do you have access to other silver fillers with different silver %? Do you know the strength of the 30% and how much fillet build up is needed?
Sorry if I have more questions than answers. Andy.
Andrew, thanks for your reply.
As a retiree, I build about one frame a year. So far, about 20, the last 6 XCR.
With Fillet Pro, test joints always ran through completely.
My current solder (Fortargen AF 319 36%) has a liquidus temp of 710°C, a melting range of 630-730°C, and a tensile strength of 360-480 N/mm.
The fillet width is about 8mm and it is concave.
I was actually hoping there would be frame builders with experience with a similar technique.
I have since built up the fillet, using flux on the inside of the downtube and more with the torch on the inside of the head tube; this time it has run through completely.
Martin
Martin (and thanks for using your name here:)) - Your building sounds much like what I’ve done for a few decades, about a frame a year. I just painted my 56th in my new painting space. I did the painting on my first half dozen+ then lost that space and have had over a dozen painters do my “frame a year” paint jobs till recently.
I just looked at Harris’s 56% silver filler (very common here in the US) and see the temp range is lower than the 36% you mention. Ideally one would want the opposite, the fillet filler should have a lower working temp to avoid effecting the tinning/flow filler. But so much of this “what can I do” is skill based. It looks like you’re gaining that skill with the most recent post. Andy.