Hi Neil, (Acknowledgments to Rob Meixner, and others too.)
Lots of good soldering information in this thread. I wanted to address a few of your questions about Paige Multi-Port Tips plus review a few aspects of soldering and maybe add a little information of benefit to others.
For jewelry makers hard "Soldering" (technically 'brazing') is the most important jewelry making skill to master. Sometimes this 'foundation' technique may seem like one of the "Black Arts" but it's not. Working with a soldering Torch and related elements like fuel gasses, oxygen sources, solders, fluxes, flame profiles & sizes plus the various metals we use is a learned process like other skills... if practiced with forethought and attention to reasonable details excellent results are all but guaranteed.
Although there are skilled jewelry makers using acetylene / oxy setups, often because of how they learned to solder or due to regulations restricting propane use, choosing an 'Alternative' fuel gas (e.g., propane or natural gas) is the best overall choice for jewelry making. These fuel gasses produce clean flames that are not overly hot (compared to acetylene), often are less costly re: refills and re: propane... a safer gas than many may have heard. (Look up "Flammability Ratios" of common fuel gasses for more information.) Small, hydrogen / oxy Torches offer an alternative for clean burning flames if equipment cost and generally lower, BTU heat outputs are acceptable. Propane / oxy, even natural gas / oxy are plenty 'hot enough' for even platinum bench work so either gas will basically cover all needs for typical bench soldering.
The Little Torch and Meco Midget have all but become the de facto soldering Torches lots of jewelry artists choose. Regardless of the Torch choice, the above or others Torches, it's the Torch "Tip" that defines overall flame usability. Correct Tip design is directed related to fuel gas type. Alternative fuel gas flames (propane & natural gas) preform much better with Multi-Port Tips than with single hole Tips. The latter style being correct for acetylene and hydrogen gasses. Although any Tip design will 'light a flame' with different fuel gasses important flame qualities like flame stability, BTU output, smooth profile adjustments, etc., can be greatly improved by matching Tip design to the fuel gas used.
Several questions were asked about matching Paige Tips to different soldering operations:
1. Length of time needed to carry out different soldering jobs?
2. Best part of a flame to use?
3. Best Tip number to use?
4. Physical flame size considerations?
Silver soldering (sometimes) takes a little longer than gold soldering due to the high, "heat sinking" properties of silver alloys. Large objects like a bangle or wide cuff bracelets, jewelry examples with lots of metal mass, absorb more heat before becoming hot enough allowing solder to flow thus can lengthen time to complete an operation compared to say attaching a head to a small ring shank. Less metal to heat up in the ring usually means a faster completion of a solder joint. (The sterling shank with its heat sinking property being the main 'time issue' vs. the white gold head in this case.)
In addition, physical flame size plus flame (heat) profile (reducing, neutral, oxidizing) also, directly influence how long an operation can take. Add in other considerations such as how clean the metal is, how well fluxed, joint tightness and what substrate, if any, jewelry is resting on additionally impacts how long a particular operation may take. Generally speaking the shorter time we keep objects close to or 'at' solder melt / flow temperatures the better as others have noted.
In silver and gold soldering we often use several parts of a flame to take advantage of different heat levels in the flame. Regardless of flame 'profile' (reducing, neutral, oxidizing) the lowest flame temperature is the far, end of the flame. The far end of a flame is where we often start... gradually heating the flux and overall metal. As the flux dries, melts and becomes clear (re: white paste flux) we bring the flame (the central cone "tip") closer to the area we want to solder heating the area to be soldered moderately quickly up to a point where it melts the solder... not directly melting the solder with the Torch flame. (Note: Platinum soldering is done differently so comments here are meant only for silver & gold work.) The hottest part of a flame is right on the central cone 'tip' ...not above or below the tip.
For silver alloys work: Our M-3 is the go-to Tip. Heavy bangles & cuff bracelets most people would use the M-4 and M-5 Tips. Soldering a small bowl, sculpture or like size object or annealing pieces of plate say 3" x 4" and up the MA-1 (small) Rosebud makes the job easy. To attach ear posts the M-2 Tip. Soldering tiny jump rings and/or neck chain repairs (26 gauge and smaller) try the M-1.
For gold alloys work: The M-2 & M-3 is the go-to Tip. Use the M-4 for large, heavy rings. Most people working in gold alloys would only occasionally need the powerful flame the M-5 is capable of producing with propane / oxy.
Note: Paige Tip numbers (M-1 to M-5) do not relate to other manufacturer Tip numbers. Above Tip recommendations apply to all Torches we support.
All Paige Tips, including the Rosebuds, will make physically different flame sizes 'flame lengths' according to how the Torch is adjusted. As physical flame size is increased so is BTU (heat) output. To very flame temperature (up / down) the fuel gas / oxy mix is varied. The above adjustments are the same with all Torches and all fuel gasses... propane, natural gas, acetylene, hydrogen, etc.
Hopefully this helps answer your questions. We are glad to "Talk Tips & Torches" with callers.