mat_lynch

hey all,
I'm getting ready to build my first frame and some questions are coming up.

1st is, silver or brass

I've got a Columbus Thron tubeset, and I'm inclined to go brass cause I'm a novice and
the brass should be easier to work with, no?

But is there a reason that I should def not use brass?

thx

Cynikal 

I was going to post about this as well. I would assume that silver melts at a lower temp so it would be easier to work with. Some clarification would be great.

Thanks

Dave Moulton

Yes brass is easier to use, with silver you have to be almost surgically clean, even a finger print will prevent the silver from flowing and when that happens you have to tear the joint apart to clean it and start over.

Brass will melt at an orange red heat, keep the torch moving and move it away if the metal gets too hot. In other words when the brass starts to flow, maintain that temperature and not go beyond it.

NoReg

Silver is also really expensive, I thnk the main reason people use it is because they don't have much heat from their torch. Propane or MAPP vs OA.

Cyclist0094

Here is an example of a potentially dangerous situation where a builder didn't do his prep right ( or overheated his flux) and his silver didn't flow . Fortunately the down tube stress cracked between the downtube shifters before this fork had a chance to fail, A 220 lb guy was riding this frame.
Areas circled in white indicate where the silver didn't flow but should have. The fork butt is from the opposite socket.



This frame was one of six frame failures that I know of from this builder( he has long since left town). Two of the six including this one I bought to salvage the lugs, BB and frame ends.

Heat source is not the reason I use silver. Mapp will flow brass just fine though may require a backer for steerer tubes

Dave Moulton

This is a common mistake that most new framebuilders make; they are so concerned about over heating that they don’t get the joint hot enough. A fork crown especially is a large chunk of metal and requires a great deal of heat applied The whole fork crown or at least the side you are brazing needs to be a uniform dark red heat for silver; or orange red heat for brass. When you apply the filler rod the heat will then transfer to the thinner fork blades. The brass or silver should flow instantly all around the joint and you can tell by the amount of filler rod you are using whether you have enough in there. Better to use more rather than less as the surplus will just run inside the crown.

Nessism

Far be it for me to question Dave Moulton...but...I find it easier to braze with silver. Most IC lugs these days fit very snug and need to be reamed out to get a proper clearance. Silver clearances are much easier to achieve since they don't require as much grinding. Also, with a tighter fitting joint it's easier for a novice (like myself) to keep the joint in alignment. Yes, the joint must be kept clean but this is easy enough: use acetone on the tube/lug just before slathering on the flux.

Just my opinion. Please forgive.

Ed

jacobs

I would never braze dropouts or fork crowns with silver unless they were stainless and I had to. Silver is great for lugs, as it flows so cleanly and doesn't require as much heat, but in my opinion is just a liability in the dropouts and fork.