I learned a few thing about brazing over the last few days. Some that people have told me before and have finally clicked. Others that I figured out on my own. I'm not a master by any means. However, half the motive for this blog is for my personal notes.

1.) Always work uphill with the torch pointing in the direction of travel. This gets said over and over but if you're not doing it, you need to be.

2.) Preheat: I realized that getting the whole joint dull red, including the backside of the mitered to tube, makes everything easier. It helps with distortion and it helps with heat control.

3.) Heat the inside of the tubes. I've decided that heat sinks do more harm than good because they cause cold spots and prevent you from getting the torch down the inside of the tubes.

4.) Keep the filler rod close to the flame. If the filler rod is 4" away, when you add it to the puddle it takes too long to melt. Keeping 1/2" means that when you add filler you get molten brass right away.

5.) After you add filler, make sure the puddle wets out to the root of the joint. I found myself concentrating on the shoreline of the joint. I noticed the puddle would wet out on the sides a moment before it wetted out to the front (the root). If I moved ahead and added more filler, I would create pocket and seal it when I added more filler. This may have been the reason I was getting poor penetration on my practice joints and went to a wet first fillet second technique. I may try some practice joints with one pass and see how it looks.



When I first started building this bike, I tried this joint in brass. I couldn't get it flow so I ended up using silver. I was concerned about the later joint and the higher brazing temps. You can see a bit of silver bleed out, but overall everything is fine.



Looking better still. Since this bike is being built to be ridden, this one probably won't see much filing. My goal is to get good enough so that I never have to file fillets.
As a machinist I was taught that a good machined finish is harder to achieve and therefor looks better to the trained eye than a sanded or scotchbrite finish. I feel the same way about fillets. Anybody can lay on a bunch of brass and spend an afternoon filing it all off. It takes a lot more work to make a fillet that can never see a file and still look good under paint.



BB went way smoother than I could have expected. I did have quite a hard time keeping the ST/DT intersection from overheating, but it flowed with a bit of patients.



I got the whole front end brazed up today. This is my first joint. It's not into the realm of the "no file fillet" yet, but I'm getting there. I learned a lot and things started clicking.
The homemade headtubes with the extra thick ends really paid off on this joint. I had zero issues with heat control even though the brass went right up to the edge. My TT is only 7mm from the top edge of the headtube.