MAPP gas & Safety-Silv 45

[tjk2]

Hot enough?

I'm limited to a basic Bernzomatic for soldering brass. Do you have a single preferred solder and source?

How about brass half oval? Got a less pricey supplier than the "museum" one?

[james gielow]

I used to use a Bernzomatic with a high lead solder because it never seemed to get quite hot enough for solder with a higher silver content. The problem was the joints weren't properly brazed and were very weak. In some tests I did, I actually had failure which would be very bad if it happened during an earthquake on an actual object.

That was enough for me to upgrade to a "B" type acetylene tank and torch, which was relatively cheap considering how much use we get out of it. The tank itself was $160 and refills are around $35 and the torch outfit was about $150.

I use Safety-Silv 56 for the brazing and Stay-silv white brazing flux and the joints have been perfect. No failures and I'm told they are as strong, if not stronger, than the brass itself. Since then I have never looked back.

As for the half round brass, I've never used it. In some cases where it would be needed (and as long as the mount was small enough) I would use bar stock and round over one side on my 1" upright sander. So much cheaper that way. I get all our brass from McMaster-Carr. Hope this is useful.

[Jamie Hascall]

I was a mountmaker in private practice for 12 years and used a pair of Bernzomatic trigger start torches for all my brazing. I found no trouble doing joints in fairly heavy brass (1/4"x1") or even in steel. You can use the two torches pointed from opposite directions to create a zone of very intense heat. As the flux reaches the water clear stage you can put one down and feed the brazing alloy in. I use mostly 56% silver but there should be no problem using 45% either. If you're only able to use one torch, you can put a fire brick or two adjacent to the work to form a corner where the heat can be contained and amplified.

If you're using the most basic type Bernzomatic torch, it may have a limit to how much heat it will produce. The trigger start type are the most convenient to use and are definitely up to the job. In looking for pricing, I just found a Harris branded torch on Amazon that's going for $29.00. For that kind of money you can get two and be brazing in no time. The other advantage of this type of torch is that it is perfect for off site work as you can travel on a plane with the head and you can buy the gas at any hardware store.

As far as half oval brass, I always got mine from Alaskan Copper and Brass in Seattle, but since you're on the East coast, you should check with Jamestown Distributors or other marine industry suppliers, as well as checking into industrial copper and brass suppliers. It can't be cheap anywhere at this time but those should be a bit less than the place you're looking.

[Alan Noble]

I have been a mount maker for the past 6 years and have been learning to introduce new practices and schools of thought into my techniques. I've always used a Smith's Little Torch oxy/acetylene rig for my brass brazing needs. Only recently was I introduced to using a bernzomatic with mapp gas for this and honestly, I've had varying degrees of success with it. It's great if you need to anneal a large swath of metal, but it's fairly limited in it's ability to braze small joints. The flame is simply too big. I've been trolling the inter-webs looking for a pencil tip/jeweler's torch set up that is as compact and cord free as the bernzomatic is, but all that I have found are butane and propane based. I am currently in the process of doing the research to find out the burning temperatures of the various flames discussed and what the suggested temperature for soldering two pieces of brass together using safety silv 45 might be. There seems to be a lot of conflicting information out there but from what I have gathered, acetylene burns the hottest, about 2500 Celsius (combustion with air, as opposed to oygen), Mapp is about 2010 (with air), and both butane/propane are around 1970 degrees Celsius (with air). All of which is more than hot enough to melt the Harris Brand SS-45 at 663 degrees Celsius. Interestingly, Harris suggests using their safety silv 15 for brass to brass joints. The Harris White Stay Silv flux is active between 565 and 870 degrees. They offer a ton of PDFs here. http://www.harrisproductsgroup.com/en/Technical-Documents.aspx I have not found information yet as to what temperature the brass itself needs to get to, but I suspect it depends largely on the alloy you're using.
All of this is to say that I don't know if I can get by with a small hand held style butane torch or not. The cost of these units is fairly cheap, but I imagine the refills of the gas is where the hidden costs lie. I plan to do some tests before ever putting anything out on display of course, but I'd sure appreciate if someone could shed some light on the subject for me. Can you use butane? Can you buy a narrow flame benzomatic mapp gas torch kit?
Thanks in advance! Happy mounting!

[Jamie Hascall]

Hi Alan,

Going from a Smith's Little Torch to a larger but cooler flame will take some practice, but is possible. The concentrated heat of a small Oxygen/Acetylene torch can be hard to control, but when you get used to it, nothing else seems to have the horsepower and finesse that it does. When I tried one many years ago, I found that a Smith's gave such a concentrated flame that I'd blow right past the melting point of the silver and soon have it bubbling and weakening the joint. I've since learned to control it, but find it's not my preferred torch.

I've used MAPP gas (or the current equivalent MAP/PRO) for many years because I could take my torch head anywhere and get a small cylinder of gas at the nearest hardware store. This was especially useful working in places I needed to take a plane to. The added advantage is that there was not a sizable tank of highly explosive acetylene gas in my shop. The best of the handheld MAPP gas torches I've found is a Sievert Powerjet from Sweden. http://www.sievert.se/products/powerjet/. It comes with interchangeable tips and has a pinpoint flame tip (#870201) that is pretty good. The standard tip gives a flame nearly identical to that of a Bernzomatic. They are not cheap, but you can occasionally find them on sale. I actually got mine from Farm and Fleet's website for a good price. I use it with a short hose to the cylinder so that I don't have to heft the whole thing. That came from participant comments at one of my workshops about the awkwardness of using the torch and cylinder together. I love the trigger start and basic simplicity of this type of torch.

My current torch is a Meco Midget oxygen/propane. I like it because it has a tighter and hotter flame than the MAPP torch, but not quite as hot as Oxygen/acetylene. It will let me braze steel in ways I could not do before, and the fuel is cheaper and more available than acetylene. I love the small size and great flexibility, but it was a real splurge to invest in it. http://www.tinmantech.com/products/welding/meco-torch-accessories/meco-midget-torch.php

The other torch type that has been the standard of mountmaking shops forever is a fuel/air jewelers torch such as a Gott or Prestolite. Usually these are fueled with acetylene, but I've wondered how they would do fueled with MAPP? Harris sells a turbo-tip version that is set up for MAPP and has a fairly small tip available. It seems like it should be the hottest small flame available from something other than acetylene. It would be interesting to hear if anyone has tried one out. http://www.harrisproductsgroup.com/en/Products/Equipment/Torches/Air-Fuel-Kits/inferno-quick-connect-alternate-fuel-kits.aspx

I know people sometimes use the small butane torches to do very small work, but I've tried them and not found them to be of much use. I'd love to hear of other people's experience using them.

The other thing you may want to look at is your choice of brazing alloy. The Harris Safety-Silv 45 has a liquidus temperature of 1370°F (743°C) whereas the Safety-Silv 56 has a liquidus temperature of 1205°F (652°C). I've found the 56 to be my favorite alloy formulation use it for everything. I also use tricks of building little corner ovens of firebrick to intensify the heat if needed.

Good luck finding the torch that suits you. It's a very personal choice. Please get in touch if there are other questions I can answer.

Jamie Hascall
Mountmakingfocus.com

[Alan Noble]

Jamie,

Thanks for a speedy reply and a huge thanks for the links! I'll be giving these a try in the months to come. I think I'm going to enjoy combing through the TM website when I find the time.
I agree with you that the Smith's requires some getting use to. The same coworker who introduced me to using a mapp/pro bernz. setup, required a little training and some practice before he felt comfortable with the oxy/acetylene. It's safe to use if you know what you're doing, but it can be nerve wracking if you're just getting in to it. Personally, I like the flexibility it provides. I can go from working the smallest of joints up to large 1/2" bars (for my use this is quite large), simply by adjusting the gas flow. But sometimes quick and easy is best, especially when you're on a deadline. I'll be pushing to get a sievert in before the end of the fiscal year and I'll let you know how we make out with it.
Thanks again for the help!
Alan