I remember reading that trying to weld a crack risks re-tempering the cymbal (because of the heat involved), potentially altering its tone and weakening it. So is that actually not true?

Did Zildjian ever repair cymbals back in the 60-70's? Back in the early 70's I had a 18" A Zild crash that cracked about 2" around the bell. I brought it to my drum teachers store and they had it repaired. It was even lathed too. It sounded a little "tight" for lack of better term but after a few years it went back to the old sound it had. I never really thought much about the repair process but it was as perfect as could be.

Ok well here is a pic of the zildjian A rock crash I welded today. Very similar to the damage described by the OP. Welding the entire crack would have warped it beyond any kind of use. So I Welded both ends and the center, then removed the remaining crack, sounds good. I don't really like A's to much, but it sounds good for a rock crash in general.

[IMG]http://i45.photobucket.com/albums/f71/14pagan88/18rockcrash_zpsfe054a83.jpg[/IMG]

Here is a video link for this tig welded rock crash, the sound is just fine imo

[ame]http://www.youtube.com/watch?v=JfmXnjhOly8&feature=c4-overview&list=UUwyp35U6z1XCF4CVvetjNXA[/ame]

This process sounds like it could be expensive,is it?

Did someone tried brazing on such crack? Maybe it's possible to use some other piece of zildjian b20 as brazing alloy for that?

Yeah, I know. Heat, but we are on the bell, which has the most densed structure material on cymbal.

I have fiddled with brazing. About 10 years ago there were some specialized brazing rods of various alloys brought out by one rod company, specially for brazing bronze and brass. I tried some on a couple of cymbals with generally good success but controlling the cooling is really difficult. Cracking around the weld is always a huge threat. The key with brazing bronze , is to use a bronze rod that has a just slightly lower melting point than the cymbal, so you can flow the rod into the grooved out crack, almost like puttying a window. Perhaps a piece from a different cymbal would work with some experimentation but standard brazing rod isn't a go-----it is engineered more for brazing ferrous metals------perhaps could work , with the right flux but I didn't have any luck with it.

TIG does work o.k. but the laser welding works on even old porous uneven cast cymbals. I've seen it done on an old Chinese gong and it was a miracle.