Framebuilders - brazing cable stops to 631

Doing some research on a possible summer build.

The frame I'm looking at is made out of 631. I've done some brass brazing before, but it was always on something a lot more robust than bike tubing. What problems am I looking at if I try this? Wouldn't 631 be resilient to overheating? The other option would be generic chromoly, which I understand isn't as forgiving to inexperienced brazers.

Generic Chromoly (as in straight gauge tubing from an aircraft supply) is great to learn on, even if it makes for heavy frames.

I'd learn to do silver brazing, personally - its easier to do on a bike. A good source of material and informaiton is Fred Parr at cycledesign.org.

That said, a basic set of tubes, often known as stress relieved, would be a good place to start. Heat has many impacts - its possible to overheat anything. The basic tubes come in heavy gauges which withstand heat pretty well and heat/cool more slowly - so they are less far from the heat/cool time of lugs and other heavy bits.

Heat relieved tubing also can be played with some using heat. Heat can and often does warp a tube. My experience is that this is a more controlable variable with the more basic tubes. Put a bridge between the stays and they may end up narrower between the tips. Apply some heat to the outside of each stay and its possible to straighten them back out. Same thing with a fork leg.

So, my advice is to use the cheapest bike-specific tubing from Henry James (True Temper) or Joe Bringheli (Deda). Mix in silver filler and you should be off to a good start.