I use an acetylene torch with Smith tips. In general, it depends on
how large the piece it that you are heating.
I make jewelry and do many bezel settings. I’ve found that typically
I use either my NE-180-00 (the smallest I have) for smaller pieces
and the NE-180-0 for pieces that need more heating. I have had to use
larger tips for larger pieces on occasion, but you must remember that
with too much heat you run the risk of burning bezel or silver sheet.
This website has a nice chart of the heat output for the torches I