Making this type of wishbone stay was kinda like making a really uber lightweight fork. The upper piece that connects to the seat tube is 25.4mm (diameter) x 0.9mm (wall thickness), the crown pieces are 19mm x 0.9mm, and the legs are True Temper seat stays, 16mm x 0.6mm or thererabouts.
It’s funny to me how crappy brazing makes the workpiece look until it’s soaked to remove the flux, cleaned, filed, and brushed. My brazing work is still too hot (not good hot, bad hot) so that’s the darker colors of brass you see. The black is really bad. I’m still figuring ‘the moment’ out when it’s the exact right time to add the brass. I have the silver-brazing down no problem right now though, I just need more practice at fillet brazing.
For this wishbone stay, I stuffed a bunch of brass into the crown-segment pieces to make up the extra space between the seat stay legs and the crown pieces. I got good penetration throughout the joint so I’m pretty confident it’ll be a good and strong rear triangle once I weld it onto the rest of the frame. Once I did the fillets, I added the caps to the ends of the 3 tubes and silver-brazed them into place. I haven’t been using anything but gravity to keep the 0.025″ steel on top of the open tubes when I braze and it works just fine if I position it perfectly parallel to the ground. The flux helps keep it on there too, initially at least.
After the cleanup and filing, it looks pretty good if you ask me!
The frame is all welded, just a few more hours till it’s done done = I just have to cut the seat tube slot, add a cable stop brazeon (that I forgot to add awhile ago for the front derailleur cable), and ream/face everything…and then paint.