Welding tip sizes

In Alex Farmer's book on boiler making he lists the various welding tip sizes he uses only as B.O.C. numbers, without giving the actual tip diameter. Does anyone out there have a list of the B.O.C. tip numbers and their respective drill sizes? I have a Liquid Air torch and their numbering system is totally different. In fact I have a chart that compares Linde,Liquid Air, Purox, and Harris tip sizes and non of them are the same! Obviously there's no industry standard.

John Purdy

Edited By John Purdy on 29/01/2016 18:04:27

Gas, TIG, MIG, MMA? Give us a clue.

oxy-acetylene

John Purdy

John, your not thinking of oxy welding a boiler are you? If its for silver soldering then any half decent size will do. You will be amazed at just how much heat is needed for even a copper 5" boiler, so adjust it with the flow controls.

This piqued my curiosity, so I've just had a furtle in the shed with my set of BOC nozzles. I have a set of the swaged copper nozzles to suit a BOC Sapphire 3 torch, and by dint of poking bits of wire and small drills up the orifice I've come up with the following:

#1 nozzle is 0.6 mm dia, #3 = 0.8 mm, #5 = 1.0 mm

#7 = 1.3 mm, #10 = 1.4 mm, #13 = 1.6 mm

#16 = 1.8 - 1.9mm (1.8 is loose, 1.9 won't go), #25 = 2.0 mm, 35 = 2.4 mm

It's hardly a precision measurement but it'll give a rough guide.

If anyone has got one of the sets of wire reamers BOC sold for nozzle cleaners these would give the sizes more accurately. I've always assumed that the numbering system, though peculiar to BOC, was the same for all their torches, but I haven't checked. Am I right in thinking the numbering system is related to the fuel gas consumption in some way?

As Fizzy says above, for silver soldering something as large and as heat-dissipative as a copper boiler you'll want a bloody big flame and I would think quite possibly a second torch - probably propane - to help with getting the whole thing pretty hot, then go in with the oxy-acetylene to trim the local temp' and get the solder to flow. Getting a structurally sound joint is a matter of getting on with the job, getting a structurally sound and pretty result is another stage of magic again. My Dad was a silversmith, and together we hard soldered some pretty crazy things (the broken antler on a brass statue of a deer was one) but you don't have time to hang around before the flux stops absorbing oxygen and you're knackered. That was with JM EasyFlo flux; I gather there are better fluxes around now, so good luck!

Do let us know how it goes. Rgds Simon

Fizzy

No! I've built built 3 boilers, two for 3 1/2" gauge locomotives and one a 3" dia. test boiler, all with propane. The two loco boilers were done with a 1 1/2" dia. burner. My next boiler is for a 3 1/2" gauge narrow gauge D&RGW K28 2-8-2 loco. The boiler is 6" dia. by 23 inches long and 5 1/2 across the back head. I got Farmer's book as guide to building it using Propane for pre-heat an then the oxy-acetylene for the final heat up to soldering temperature. His book describe how to build a large boiler using oxy-acetylene as the final heating medium. But he only lists the recommended tip sizes by BOC #, Not much use to us that don't have BOC equipment. Hence my initial question.

John Purdy

Oops! My apologies, I think I've just committed the sin of trying to teach my grandmother to suck eggs, though in this case it's my grandfather to cook them!

But I'd love to see the results?

Anyone tried tig brazing a boiler?

Simon

Thanks for your info. That will at least get me in the ball park. Alex Farmer recommends tip sizes of 11, 13, and 18 for the various operations. I have a Liquid Air #312 torch and they list their tip orifice sizes by # drill size, 00 being #76 and 13 being #12. As an aside when doing the loco boilers I found I could not keep the propane torch flame lit when trying to solder the stays inside the firebox (3" x 3 1/8" x 3 1/2 deep) . As soon as I got it close to the end of the firebox it would blow out. That's a problem with naturally aspirated propane torches, they don't like being directed into closed spaces. I eventually bought a multi-flame heating tip for my oxy-acetylene torch and used it with propane and oxygen. Did the greatjob but sure used up the oxygen.

John Purdy

John, I still dont get it? Just put a decent size tip in and turn it up or down as desired. Your not using the torch to weld so anything quoted for welding will be irrelevant (am I missing something?). A boiler the size of yours will need a lot of heat and quite rightly you are also using propane.If youve not used oxy for silver soldering before let me give you some advice (If you have then great). You want a big flame/nozzle size and you want it running oxy weak. The cone needs to be at least an inch long so as to protect your boiler. If you use a fierce flame as you would for welding you will either end up burning the copper or melting a tube, or both. Oxy looks like the ideal solution to heating but it requires a much greater degree of skill and caution than propane. Dont try to get it up to temoerature too quickly, and dont point the flame directly at the joint. If you do then the silder melts and is blown everywhere except where you want it to be. I tell you these things from experience, not from the armchair. Hope all goes well.