For all you silver solder experienced, what is a good torch , not terrible expensive, and silver solder to buy? I plan on using the silver solder for the crank to crankshaft connection on the Webster engine build. I do have an old Bernzomatic OX-2500 with small oxygen and propane tanks, and I would think it would work; but, I was wondering what to buy that is more modern and will work well with just the small Coleman propane tanks. Also, which silver solder to use would be helpful.
Silver Solder Torch Selection
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Daniel Williams
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I use Harris Safety Silv 56 for the silver solder, and Harris Stay-Silv white flux. For the torch, when the part isn't terribly big I use Bernzomatic Mapp gas (yellow tank) and use the proper torch head for Mapp gas. For bigger jobs, I use oxy acetylene with a gas weld torch tip. With the acetylene torch, I keep the gas flame rather gentle, not ripping. If soldering really large stuff, one of the seivert propane heads will get enough heat in. Blondihacks does a great series on silver soldering a copper boiler for a Kozo locomotive.
The trick to silver soldering is to get heat into the part quickly to get the flux to activate and then have the solder melt shortly after. If it takes too long to heat the part, the flux will activate and get used up, rendering the soldering process useless. If you get too much heat in, you'll use up the flux and then burn it. Clean everything up and start over.
I always flux the heck out of really clean parts, and then apply small cut pieces of #56 solder into the joint with the flux. Never try and apply the solder while heating, like you would when electronic soldering. It almost never works. After placing the pieces of solder around the joint, start the heat process. The flux will dry, then start to melt. when it starts to melt, the solder should start to melt shortly after. The solder will wick right into the joint. A little solder goes a long way in wetting into a proper joint. If not enough solder, cool it down, add more flux and more pieces of the solder and start over again. You need a few thousandths gap between parts for the capillary action to suck the solder in, too much gap and it won't close up the gap.
To get rid of the flux (glass like stuff) after soldering, I use citric acid crystals diluted in warm water. It is used for canning, that's where I found it at the grocer. Also, Sparex Pickling Compound (Amazon) is widely used for removing flux as well, both clean up the parts really nice.
Best of luck,
Dan
The trick to silver soldering is to get heat into the part quickly to get the flux to activate and then have the solder melt shortly after. If it takes too long to heat the part, the flux will activate and get used up, rendering the soldering process useless. If you get too much heat in, you'll use up the flux and then burn it. Clean everything up and start over.
I always flux the heck out of really clean parts, and then apply small cut pieces of #56 solder into the joint with the flux. Never try and apply the solder while heating, like you would when electronic soldering. It almost never works. After placing the pieces of solder around the joint, start the heat process. The flux will dry, then start to melt. when it starts to melt, the solder should start to melt shortly after. The solder will wick right into the joint. A little solder goes a long way in wetting into a proper joint. If not enough solder, cool it down, add more flux and more pieces of the solder and start over again. You need a few thousandths gap between parts for the capillary action to suck the solder in, too much gap and it won't close up the gap.
To get rid of the flux (glass like stuff) after soldering, I use citric acid crystals diluted in warm water. It is used for canning, that's where I found it at the grocer. Also, Sparex Pickling Compound (Amazon) is widely used for removing flux as well, both clean up the parts really nice.
Best of luck,
Dan
Harris also makes a brown flux with a higher temperature rating, and it will take more heat than the white flux before it burns off.
The flux will dry out, and you can mix it with a little water to get it like puddy again.
It takes a surprising amount of heat to reach the temperature where the silver solder will flow.
There is a fine line between reaching the right temperature and burning off the flux.
.
The flux will dry out, and you can mix it with a little water to get it like puddy again.
It takes a surprising amount of heat to reach the temperature where the silver solder will flow.
There is a fine line between reaching the right temperature and burning off the flux.
.
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BobsModels
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Hi
I am in complete agreement with Dan and Green Twin. Especially flux and cleaning.
Planning your job is important, you need to think about how much heat you need and where.
I use many different silver braze rods with different melt temps (Easy Flow and 56 two most used), also Harris Stay Brite #8 for a high temp silver bearing solder.
A recent project involved silver brazing was a crankcase for a 2 cylinder model. It is about 6” x 3” x 3” high. It had 19 separate brass pieces ranging in thickness from .1 to .25. Lots of sequence planning, I used three different melt temperature silver braze and one high temp silver solder. It took me several days with lots of trips to the pickle tank, fixtures and rest time. It was all done with a Sievert Propane system.
Here is what I use for various brazing / soldering jobs:
Mapp with a real old torch head - small items say no thicker than 3/16, depends on overall size, or larger with hot plate help
Oxy - Acy
Smith Little torch with low pressure Regulators - very small delicate items less than 3/32
Smith AW series (tips 000 to 7) – when I need lots of heat concentrated small or large
Sievert – on 20 Gal propane tank with Victor regulator to 40# (see Photo)
- When I need lots of heat on a large surface area, or round to flat (special tip)
I would guess that 60% or more of the items I silver braze for parts over the years used the Mapp torch. May take a minute or so more to heat up if using large materials but requires less setup ie getting out the tanks, the tips, etc.
Bob
I am in complete agreement with Dan and Green Twin. Especially flux and cleaning.
Planning your job is important, you need to think about how much heat you need and where.
I use many different silver braze rods with different melt temps (Easy Flow and 56 two most used), also Harris Stay Brite #8 for a high temp silver bearing solder.
A recent project involved silver brazing was a crankcase for a 2 cylinder model. It is about 6” x 3” x 3” high. It had 19 separate brass pieces ranging in thickness from .1 to .25. Lots of sequence planning, I used three different melt temperature silver braze and one high temp silver solder. It took me several days with lots of trips to the pickle tank, fixtures and rest time. It was all done with a Sievert Propane system.
Here is what I use for various brazing / soldering jobs:
Mapp with a real old torch head - small items say no thicker than 3/16, depends on overall size, or larger with hot plate help
Oxy - Acy
Smith Little torch with low pressure Regulators - very small delicate items less than 3/32
Smith AW series (tips 000 to 7) – when I need lots of heat concentrated small or large
Sievert – on 20 Gal propane tank with Victor regulator to 40# (see Photo)
- When I need lots of heat on a large surface area, or round to flat (special tip)
I would guess that 60% or more of the items I silver braze for parts over the years used the Mapp torch. May take a minute or so more to heat up if using large materials but requires less setup ie getting out the tanks, the tips, etc.
Bob
Harris 56 also. I use an oxy-acetylene torch because unless the part is fairly small, I don't find propane to be hot enough. Maybe MAPP if it's still around.
We are talking silver BRAZE not solder. The silver solders seem to be more like 4 percent silver, and I didn't like the way they worked. Maybe I didn't practice enough with it. Also, don't expect the same strength with the silver solders. Get some insulating firebricks to work on, maybe make a containment for the heat.
Doug
Edit, and another thought, oxy-acetylene, or oxy propane make much higher temps, but also allow you to change the mixture so it is slightly rich (carburizing flame) to help limit oxidation.
We are talking silver BRAZE not solder. The silver solders seem to be more like 4 percent silver, and I didn't like the way they worked. Maybe I didn't practice enough with it. Also, don't expect the same strength with the silver solders. Get some insulating firebricks to work on, maybe make a containment for the heat.
Doug
Edit, and another thought, oxy-acetylene, or oxy propane make much higher temps, but also allow you to change the mixture so it is slightly rich (carburizing flame) to help limit oxidation.
I use a standard oxy-acetylene torch, with the heating tip.
The larger the piece to silver solder (braze to be exact, but silver solder is the term I have always heard), the larger the tip, and the higher gas flows required.
The term "silver solder" gets confusing because there are low temperature solders with a bit of silver in them, but very low strength, and then there is high temperature/high strength silver soldering rods and the high temperature process, which is what I think of when I see the term "silver solder".
The first time I tried to silver solder some steel pieces, I burned off the white flux I was using, and then when the piece was hot enough for the silver solder to flow around the joint, the silver solder would not wick into the gap, because the flux was overheated.
A joint that does not wick completely is very low strength. It can look superficially very good, but be very weak.
I have not done it in a while, but it seems like I would heat the metal surrounding the joint, but not train the flame directly on the joint, so as to not overheat the flux. Perhaps training the flame all over and on the joint once the metal flowed and wicked into the gap.
I recall using a punch to create tiny dimples between the pieces, to give the silver solder somewhere to flow.
The thinner the joint, the stronger it is, so keep the joint clearance small.
Wire brush all the joint surfaces well, and clean some of the metal away from the joint too.
Immediately coat the cleaned metal with flux; don't let the cleaned metal sit bare in the atmosphere.
And brazing with silver solder is not like brazing with a brass rod.
With a brass rod, which can have a flux coating (the ones I use have the coating), you can build up and fill a very large gap or crack.
With siver solder, it flows in a very fluid fashion, and the idea is for it to wick into a very thin space between the parts, perhaps 0.001" or a little more clearance.
I don't think you fill large gaps with silver solder because it is too fluid.
You should try some test pieces using the same metal that you will use for your final pieces, and get the feel for the heat required.
And I recommend cutting or otherwise destructing the test pieces to make sure you are getting complete flow into and around the entire joint.
I recall when I first tried silver soldering, having to get the entire joint dull red hot, which was significantly hotter than I expected, and required quite a bit of heat out of an oxy-acetylene torch.
I seem to recall the flux instruction sheet said use good ventilation, and don't breath the fumes.
.
The larger the piece to silver solder (braze to be exact, but silver solder is the term I have always heard), the larger the tip, and the higher gas flows required.
The term "silver solder" gets confusing because there are low temperature solders with a bit of silver in them, but very low strength, and then there is high temperature/high strength silver soldering rods and the high temperature process, which is what I think of when I see the term "silver solder".
The first time I tried to silver solder some steel pieces, I burned off the white flux I was using, and then when the piece was hot enough for the silver solder to flow around the joint, the silver solder would not wick into the gap, because the flux was overheated.
A joint that does not wick completely is very low strength. It can look superficially very good, but be very weak.
I have not done it in a while, but it seems like I would heat the metal surrounding the joint, but not train the flame directly on the joint, so as to not overheat the flux. Perhaps training the flame all over and on the joint once the metal flowed and wicked into the gap.
I recall using a punch to create tiny dimples between the pieces, to give the silver solder somewhere to flow.
The thinner the joint, the stronger it is, so keep the joint clearance small.
Wire brush all the joint surfaces well, and clean some of the metal away from the joint too.
Immediately coat the cleaned metal with flux; don't let the cleaned metal sit bare in the atmosphere.
And brazing with silver solder is not like brazing with a brass rod.
With a brass rod, which can have a flux coating (the ones I use have the coating), you can build up and fill a very large gap or crack.
With siver solder, it flows in a very fluid fashion, and the idea is for it to wick into a very thin space between the parts, perhaps 0.001" or a little more clearance.
I don't think you fill large gaps with silver solder because it is too fluid.
You should try some test pieces using the same metal that you will use for your final pieces, and get the feel for the heat required.
And I recommend cutting or otherwise destructing the test pieces to make sure you are getting complete flow into and around the entire joint.
I recall when I first tried silver soldering, having to get the entire joint dull red hot, which was significantly hotter than I expected, and required quite a bit of heat out of an oxy-acetylene torch.
I seem to recall the flux instruction sheet said use good ventilation, and don't breath the fumes.
.
It is not so much the flame temperature that matters but the total heat output. So for fabrications a propane torch along the lines of the Sievert that Bob shows with a 28mm burner will do for most things. This puts out about 7.7Kw so you will have to convert than to whatever you rate them by in the US.
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I find that no matter what type of torch you use start heating away from the area that needs to be soldered. That way the Flux isn't burned up while trying to get the area up to heat. As the Flux turns watery looking then concentrate the heat to the area to be joined. Don't be afraid to try a couple of practice pieces beforehand. Remember, the solder will flow toward the heat so after the solder becomes liquid you can draw it around the joint by moving the heat along the joint. For a crankshaft, put a small chamfer on the outside of the cheeks at the crank pin and inside where the main shaft goes through.. I also have found that once the joints have been soldered play the heat all over the pieces so they can cool evenly. That way it tends to eliminate any thermal stresses from one area being hotter than another
Thank you for all the responses. Although I would love to have an oxy acetylene set-up, it is an expense I do not desire in light of the lack of use I will get from it. I will stick with what I have, and also get a Mapp (current version) torch. As for the silver solder, I have been looking for the recommended one the Harris 56.
I found this one at Amazon: https://www.amazon.com/Harris-Troy-Ounce-75310-5631/dp/B0713Y6V2F
It is a bit more expensive than I thought it would be. Does the quantity in the link go a long way? It looks like it would. Would this be good for I.C. fuel tanks and for steam engine boilers? Anyone have less expensive sources?
I found this one at Amazon: https://www.amazon.com/Harris-Troy-Ounce-75310-5631/dp/B0713Y6V2F
It is a bit more expensive than I thought it would be. Does the quantity in the link go a long way? It looks like it would. Would this be good for I.C. fuel tanks and for steam engine boilers? Anyone have less expensive sources?
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When I refer to "Silver Solder" I mean Jeweler's Silver Solder, which is 65% – 75% Silver:
that has a higher melting point than the Silver Brazing alloys due to the higher Silver content; also costs significantly more. Silver-Bearing Solders are those with 3 – 5% Silver, added to soft solders primarily for appearance of the finished joint.
For torches, it depends on the size of the pieces to be joined:
For small pieces or those requiring pinpoint heat I use my Smith® Little Torch™ (lower left, above), running O2 & MAPp (can also run on O2/Acetylene); for larger pieces I have a Rosebud tip for the Little Torch™, or use my Orca Torch on Propane (lower right). Cheap versions of the Little Torch are also available, but I don't know that I would trust them.
that has a higher melting point than the Silver Brazing alloys due to the higher Silver content; also costs significantly more. Silver-Bearing Solders are those with 3 – 5% Silver, added to soft solders primarily for appearance of the finished joint.
For torches, it depends on the size of the pieces to be joined:
For small pieces or those requiring pinpoint heat I use my Smith® Little Torch™ (lower left, above), running O2 & MAPp (can also run on O2/Acetylene); for larger pieces I have a Rosebud tip for the Little Torch™, or use my Orca Torch on Propane (lower right). Cheap versions of the Little Torch are also available, but I don't know that I would trust them.
In the UK any model engineer when talking about silver solder will not be talking about jewelry solder. We used to be able to use a 42% silver content but that contained cadmium which is now banned so have to use a 55% silver, no need to pay for more silver than you need on a model as it is not going to be hallmarked. Our 55% is very similar to the Harris #56
However it is best to avoid going for lower silver content as the melting point is higher. The #50 you linked to is a higher melting point solder than the #56 others have suggested. It might cost a bit less but it will be harder to produce a good joint.
I would not go the mapp torch route as they don't have such a high heat output for general fabrication work, OK for small stuff. You end up exhausting the flux before you can get the job upto temperature and then the solder won't flow. A typical Mapp torch only puts out around 2kW, the propane ones 7.7kW
However it is best to avoid going for lower silver content as the melting point is higher. The #50 you linked to is a higher melting point solder than the #56 others have suggested. It might cost a bit less but it will be harder to produce a good joint.
I would not go the mapp torch route as they don't have such a high heat output for general fabrication work, OK for small stuff. You end up exhausting the flux before you can get the job upto temperature and then the solder won't flow. A typical Mapp torch only puts out around 2kW, the propane ones 7.7kW
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Richard Hed
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I find that if I look hard enough, I can find about 97% of any item that shows up on amazog can be found cheapr somewhere else. All amazog does is re-sell what can be found elsewhere. Too oft true with flea-bay too.
That’s OK: having worked with & for companies in England, Wales & Scotland I am used to those in the UK using different terminology in a lot of cases.
peterl95124
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Stay away from Oxy-anything, its totally unnecessary, costs a lot more, and you're very likely to melt the parts you want to braze, I use air-propane and air-MAPP :-( !!!
I have some Harris black paste but never use it, only the white stuff. The white turns clear when it melts and you can see through it to the parts you're brazing which is very important so you ca see where the silver has flowed anywhere it has not yet flowed. not so with the black stuff, you're in the dark and making guesswork out of it.
If you think you need the black stuff you're probably doing something wrong, it's designed for automatic induction brazing of carbide tips onto tools where the two metals don't heat up evenly and one of them drastically overheats and there's nothing that can be done about it in automated induction heating, which we don't do in the hobby world.
I have some Harris black paste but never use it, only the white stuff. The white turns clear when it melts and you can see through it to the parts you're brazing which is very important so you ca see where the silver has flowed anywhere it has not yet flowed. not so with the black stuff, you're in the dark and making guesswork out of it.
If you think you need the black stuff you're probably doing something wrong, it's designed for automatic induction brazing of carbide tips onto tools where the two metals don't heat up evenly and one of them drastically overheats and there's nothing that can be done about it in automated induction heating, which we don't do in the hobby world.
It appears that propane torch is the most popular opinion. I found this Goss torch at a local plumbing store. https://www.gossonline.com/air-propane-equipment/hand-torches/trigger-torch
Anyone use one of these? Is this a good one insofar as for the intended purposes stated in this thread?
Anyone use one of these? Is this a good one insofar as for the intended purposes stated in this thread?
