I thought some information about the differences between using oxyacetylene or oxygen/propane might be interesting for those wanting to get their own equipment to make frames. I've used both. I learned how to hearth braze (a giant natural gas flame heating up a whole joint surrounding by firebricks) when I apprenticed in England as well as braze with brass using an oxyacetylene torch. We set up our framebuilding shop in Ukraine (where we make bicycles for pastors) with an oxygen/propane unit. I use oxyacetylene in my shop in Niles, MI and have recently set up to braze with propane as well. It is possible that some might like to use propane because it can be much easier to buy and transport and possibly be cheaper. Sometimes city ordinances prevent its use in residential areas (particularly in big cities) and sometimes welding supply stores won't sell bottled gases to non businesses or let you leave with one of their/your bottles unless it is carried certain ways. And insurance policies may limit where acetylene tanks can be located. Propane is less regulated because of its common home use in grills, etc. Welding stores can be ignored entirely if an oxygen concentrator is used instead of bottled oxygen. Those are the machines that keep grandma alive when her lungs aren't working well any more. Many of my framebuilding class students find using propane a better option. Here are some of my observations between the 2 types of fuel.
A propane torch is slightly more fussy to light than acetylene but has a cleaner flame. It doesn't rain soot if it isn't turned up rapidly enough. A propane flame wants to detach itself off of the torch tip. Once oxygen is added it can be turned up more. It will blow itself out easily if the adjusting knobs are turned slightly too much. Propane doesn't have distinctive visible inner cones like acetylene to assist in adjusting to a neutral flame. Its also noisier. It is necessary to go up a tip size or two to get the same heat volume. For example I commonly use a Smith AW205 tip on my AW1A torch handle. In Ukraine I use the AW207 with propane.
A propane flame isn't quite as hot and the bigger tip required to put out the same amount of heat isn't quite as sharp. This isn't usually a difficulty when silver brazing lugs. And could actually be an advantage for beginners because it is slower to heat up giving them more time to analyze and adjust. However I feel it makes fillet brazing a little more challenging. That said I fillet braze joints in Ukraine with propane without any difficulty. It is easy for me to adjust to using either one.
While most oxyacetylene equipment will work with propane, some adjustments will make it work better. For starters, Victor propane #-TEN torch tips have a slight recess at the end of the tip hole to help keep the flame attached. They screw onto the end of a UN-J mixer/elbow that attaches to a J-28 torch handle. Smith's NE series of propane tips designed to screw onto the end of their propane only AT61 mixer/elbow (that go to their AW1A handle) are too big for general framebuilding use. They don't have a recess in their tip. The Victor UN-J unit can also be used with acetylene with their TE series of tips. The T series of rubber hoses are recommend for propane. Standard welding hoses won't last as long.
How to use an oxygen concentrator instead of bottled oxygen is a separate subject.