Propane + air silver soldering small parts?

Check this out. Air-Acetylene for silver brazing.

You can get the little B or MC bottles from any plumbing, HVAC, or welding supply.

If you really need a lot of heat, get this tip.

tom

I'm not sure you can get the heat you need in a little flame using propane/air.

You probably already know it, but the nicest way to go would be a Meco torch set up for propane/oxygen. After the initial investment, the oxygen costs on such a little torch would be insignificant. A small bottle, costing maybe $25 to refill should last you years.

" snipped-for-privacy@spambot.com" wrote: (clip) $10 for 15

^^^^^^^^^^^^^^^^^^^^ That doesn't right true. It has to be a LOT cheaper than that to run a small O/A or O/propane torch.

(...)

How about MAPP gas?

--Winston

Forget that Bernzomatic low-pressure Oxygen, and get a real Oxygen tank from a welding supply. My last fill of 80 Cu. Ft. of Oxygen was $23 including the cylinder rental for N years. The tank lasts me for years before I need a refill. I used a bigger tank and regulator in place of the Bernzomatic Oxy tanks for a while, but eventually got a "real" torch on eBay, and moved up to a larger set of rental tanks.

Jon

He's using those red Bernzomatic low-pressure Oxygen bottles, same size as a propane torch bottle. Very little O2 in there at that pressure.

Jon

That'd be my suggestion as well - one of the top two outfits on that page, depending on the actual size of the parts. Additional larger or smaller tips are inexpensive. I think the Swirljet tips would be unnecessarily harsh for the intended use.

A MAPP torch like this would probably also work, but nowhere near as well.

For some small stuff I use an OA torch, my normal torch goes down to 1 cubic foot/hour IIRC range tip wise, this other torch starts at about that size and goes lower. Fuel consumption is negligable so I don't don't where you get $10 for 15 minute use. I'm in the UK and your price seems expensive. Another option might be to look into a water torch, they seem to be used by jewelers .

One of these:

Or this one (requires oxygen, but it is cheap as soon as you do have a bottle)

I do have the last one (cute!) and one of the upper three ones. All do their job, it depends on what exactly you want to do.

Nick

I've got an air acetylene torch, from a garage sale. the Pre-To-Lite torch came with a rather small tip, they have different size tips. Might suit your needs.

The torch wasn't hot enough for doing silver brazing of copper tubing, so I got the larger tip, which worked fine.

the first photo on the page is what I have. Every few years, I have to take the tank to a welding supply place, and get a new tank. But, that's well worth the trouble.

You've got a couple of problems here. You want to use low-melting point silver BRAZING filler, this stuff does exist, will work with the Bernzomatics with the disposable bottles. The problem is that it's mushy stuff at that temperature, doesn't wick into the joint very well and will give you lots of lumpy joints. On small work, the flame is way too large, too, you can end up with a lot of scale and/or zinc loss if you're working with brass or brass-ish alloys. Those low melting-point fillers tend to be at the bottom of the strength charts. It's all my dad and I had for years, but the results weren't pretty, took a lot of filing for cleanup.

Next step up is the Prestolite air-acetylene units, these are used by plumbers and HVAC guys. I've seen these in various conditions in pawn shops for $50-100 with regulator and tank. Some of these have interchangeable tips so you can match the tip size to the job. These will do a creditable silver brazing job, you still have to watch your filler melting point, though. You can get the work hot enough to get a good capillary wicking job and it won't take forever to get the temp up to do it. Scale will be reduced. You can use the higher strength fillers.

What I recommend is finding a small acetylene welding outfit, OA does an outstanding job of silver brazing, a matter of seconds. Takes me longer to purge the hoses than to get brazing temp on the small gun jobs I do. You've got to be fast or the filler boils. Tanks last forever doing just brazing. For really small jobs, I've got the Smith Little Torch set, I've gotten years out of a set of small OA tanks with that. Because it's fast, there's very little scale, most just washes off getting the flux off. If you're serious about doing the job well and are doing it for money, get an OA rig. I got mine for $60 at auction.

Stan

Stop messing around - go talk to your local welding supply shop. A small Oxygen-Acetylene rig is what you need, and for the lower temperature work you can switch to Propane or MAPP with air or Oxygen to get better control for low-temp work -

Problem is when you are working on brass instruments you have to be VERY careful with the temps - when you reach brazing temps you aren't too far from melting the base metal, and that would be bad.

Acetylene has a lot of energy and may be too much heat for working with sheet brass , but most small and medium torches will run just fine on Propane as the fuel gas with the right tips and pressures.

You can use large tanks and regulators with small torches - the hoses all mate together.

The main tricks are:

1. You can't use a big torch with tiny regulators (not enough flow). You can't use big tips with high flow requirements from small acetylene bottles (max draw 1/7 cylinder capacity per hour).

(MC Acetylene cylinders are so small as to be almost worthless for anything but tiny tips. And you have to be careful with the flow rate on B Acetylene cylinders - no big welding or Rosebud heating tips.)

1. You can NOT use Copper or Brass tubing for carrying acetylene to the torch (copper acetylide salts form, are really shock sensitive and can go BOOM!) so use only approved hose fittings.

1. You can NOT run the acetylene torch or hoses higher than 15 PSI past the regulator or it can get unstable and go BOOM!

2. And you can only use Grade R welding hose with Acetylene, but Grade T hose handles Acetylene OR Propane OR MAPP OR Natural Gas.

Depending on how small you want to go, there are Prestolite air-acetylene torch handles, or ESAB/L-Tec/Purox "miniature" torches and tips that can handle tiny to medium work.

Forget about those miniature Bernzomatic 1.1 Cubic Foot oxygen bottles - if they only give you 15 minutes of torch time that's a waste. Change over to a standard 50 Cubic Foot welding bottle, and you can run for 12 hours at the same flow rate on one $25-ish fill.

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I used to make jewelry as a hobby and I made a lot of it.

I used a Prestolite torch and did very well with it. However, there is one best way to go and that is with the Smith Little Torch (changed ownership now) and a "B" acetylene bottle and either a small oxygen bottle or a propane bottle (if Smith makes propane tips) and you will be set.

In fact, I am very surprised that many folks on here and the sci.engr. joining group don't have a Smith Little Torch> I darned near would bet money that once they saw one in action, they would rush right out to complete their welding repertoire.

j/b

I seldom silver solder also but when I do I use an off the shelf mapp torch. It is ok with detatched parts but too large to use near the body of an instrument.

LLLB

Which is where the Smith Little Torch comes in. You can get tips with flame size so small you have to use a magnifier to set the mixture. Haven't had to use the smallest tip in the set, yet, just put it on and fired it up one time to see what it did. Just a small blue dot. Have to use a flame to light it, a sparker won't do the job.

They also had a full range of tip accessories at one time, including bendable extension tubes in 6" and 12" lengths and ring burners that had three flames converging on the center. That's great for brazing tubing and fittings. Also had dual tip burners with the tips opposing. Don't think they're cataloged anymore, kind of specialized. Got mine before they disappeared. Got to be quick brazing copper or brass with O/A, it'll melt or boil in an instant if you're too slow.

Stan

Oh yes you can. I've been doing it for 35 years!

No,to all of this. :)

This is what I use (and have for some 35 years). Provides plenty of heat.

With a special torch for propane And coincidentally, I bought my equipment at Fischer when i lived in Pforzheim in the early 70's

See a movie where I use this equipment at

You can see me using both the torch and the bellows.

No! Welding supply shops don't know much about working on saxophones. talk to a goldsmith. I am a goldsmith, and used to dealing with material like this.

No! Much too hot,with too little control for the type of work he is doing.

I Agree. Therefore, acetylene is no good.

We know that - but don't sell the supply shop short, they DO know their merchandise. Once he identifies the gear and gases he needs he has to develop a local source for parts and repair for the gear, and to buy the gases and other consumables on a regular basis.

You can't mail order full industrial-sized cylinders of any compressed gases, they are Hazardous Materials and require special handling that the average Joe can't do properly and safely - welding suppliers are all set up to deliver if needed.

And if it breaks and you have an important job that HAS to be done by tomorrow, you need a local shop that can fix your gear today. Sending it back to the maker means you're out of business for a week.

I pointed that out! But there are times that you /do/ need the extra heat, so having it available might not be a bad thing.

Which is why I brought up using other fuel gases that are lower energy, so you aren't dancing right on the edge working with brass.

But it looks the OP missed the most important part of the post:

If you need to use Oxygen with a torch, you are throwing away lots of money on those little 1.1 Cubic Foot disposable Bernzomatic Oxygen bottles. And the disposable 1-Lb. propane bottles are almost as bad a deal per pound.

Time to buy a 50 CF or larger refillable welding Oxygen bottle, and the proper regulator and a miniature torch rig to use with it. The small cylinder drops your Oxygen cost from ~$8.00 per CF to ~$0.50 per, which is huge. Get the bigger bottle, and it's even more better.

For lower-energy fuels you also need to get away from the disposable Propane or MAPP bottles - get a 20-Lb. or larger Propane BBQ cylinder, or a bulk MAPP cylinder (refillable at welding supply), and even after buying the regulators and hoses you can save a lot of money over time.

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