It is possible not to oxidize the inside of the barrel by putting a generous amount of black oven brazing flux in the bore BUT. WARNING even if you heat the barrel all the way around evenly, so as to not warp it, the red heat will cause there to be a choked spot in the bore. After coolin the bore where heated to a temp of 1300 or more will contract about .002 to .004 when it cools. Believe me I have done a lot of them. this probably will not effect the accuracy but you will notice it when you load a tight load.
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Basic soldering
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I dont mean to butt-in here but I have welded for many years and it has been my experience that anytime you add heat to any kind of metal it will move.So how do you solder/braze lugs to one side of a barrel and keep it streight?
I have all the parts to start my first rifle and would much rather solder/braze the lugs but am very concerned about warping the barrel.
I was thinking about clamping it to a steel beam or heavy channel until it cooled completely.
I have all the parts to start my first rifle and would much rather solder/braze the lugs but am very concerned about warping the barrel.
I was thinking about clamping it to a steel beam or heavy channel until it cooled completely.
For what it's worth, there are several different "silver solders" available which do not require the high temperatures which can get into a heat range that will cause a barrel to warp PROVIDED the barrel is left to air cool.
To set the stage here, I am speaking of regular solders and a solder which used to be very common was a lead/tin mix of 60%Pb (lead) & 40%Sn (tin). It begins to melt at 361*F and is a liquid at 455*F.
A typical solder for plumbing which has replaced the high lead solders to make the anti-lead people happy is composed of 95% Sn (tin) and 5% Pb (lead). It starts to melt at 452*F and is a liquid at 464*F. Very close to the older 60/40 solder.
These regular lead/tin solders work very well for joining the parts of front sights, nose caps, ramrod thimbles and other joints that do not require high strengths.
Any regular solder is stronger than the epoxies on the market.
The silver solders are useful for soldering things like underlugs and other things that require more strength than the regular solders can provide.
The lead/silver solders vary but there is a 97.5% Pb (lead)/2.5% Ag (silver) which starts to melt at 579*F and is a liquid at 579*F. (Its Solidus/Liquidus temperature is the same so it goes directly from a solid to a liquid.)
Another silver solder is 94.5% Pb/5.5%Ag which starts to melt at 579*F and is a liquid at 689*F. This particular solder has the highest liquidus melting temperature of all of the solders listed in the "Materials Engineering" book I'm looking at.
Then there is a tin/silver solder composed of 95% Sn (tin) and 5% Ag (silver). It starts to melt at 430*F and is a liquid at 473*F.
There are many more lead/tin, lead/silver and tin/silver solders but you get the idea here.
None of them require the use of an acetylene torch and none of them require temperatures which will effect the metallurgical properties of mild steel nor do any of these require special jigs and fixtures to support a gun barrel IF THE BARREL is heated gently and uniformly and allowed to air cool.
Now, for the silver alloys Paul was referring to.
Some call them "High Temperature Solders" but in reality they are really known as Silver Brazing alloys. Brownells, much to my disappointment is one of the places that has a 1205*F Silver braze that they call "Silver Solder". They should know better.
All of them require temperatures above 1095*F to melt and some of them go as high as over 1800*F.
The 1095*F is just a few degrees below the melting point of Aluminum and the 1800*F temperature is well into the temperature range used for carborizing and hardening many steels.
The use of these brazing alloys requires a oxyacetylene torch as a minimum and special controlled atmosphere furnaces are preferred.
IMO, none of these silver brazing alloys should be used by a novice like me on a gun because of the difficulty of heating the part, the distortion or warping of the part and the possibility of having the braze alloy contaminated by air or oxides.
People who are advanced welders will know how to work with these alloys but folks like me would be advised to leave them alone.
That doesn't mean that the silver braze alloys are not used on guns.
The big factories who have the specialized equipment often use them to silver braze double barreled guns barrels, ribs and other items that require exceptionally high strength brazes.
Using silver braze also allows the barrels to be heated for the low temperature regular or silver solders without the danger of melting the barrel joint at later stages of the manufacturing processes.
I hope this helps someone get a feel for the various solders and the temperatures required to work with them.
To set the stage here, I am speaking of regular solders and a solder which used to be very common was a lead/tin mix of 60%Pb (lead) & 40%Sn (tin). It begins to melt at 361*F and is a liquid at 455*F.
A typical solder for plumbing which has replaced the high lead solders to make the anti-lead people happy is composed of 95% Sn (tin) and 5% Pb (lead). It starts to melt at 452*F and is a liquid at 464*F. Very close to the older 60/40 solder.
These regular lead/tin solders work very well for joining the parts of front sights, nose caps, ramrod thimbles and other joints that do not require high strengths.
Any regular solder is stronger than the epoxies on the market.
The silver solders are useful for soldering things like underlugs and other things that require more strength than the regular solders can provide.
The lead/silver solders vary but there is a 97.5% Pb (lead)/2.5% Ag (silver) which starts to melt at 579*F and is a liquid at 579*F. (Its Solidus/Liquidus temperature is the same so it goes directly from a solid to a liquid.)
Another silver solder is 94.5% Pb/5.5%Ag which starts to melt at 579*F and is a liquid at 689*F. This particular solder has the highest liquidus melting temperature of all of the solders listed in the "Materials Engineering" book I'm looking at.
Then there is a tin/silver solder composed of 95% Sn (tin) and 5% Ag (silver). It starts to melt at 430*F and is a liquid at 473*F.
There are many more lead/tin, lead/silver and tin/silver solders but you get the idea here.
None of them require the use of an acetylene torch and none of them require temperatures which will effect the metallurgical properties of mild steel nor do any of these require special jigs and fixtures to support a gun barrel IF THE BARREL is heated gently and uniformly and allowed to air cool.
Now, for the silver alloys Paul was referring to.
Some call them "High Temperature Solders" but in reality they are really known as Silver Brazing alloys. Brownells, much to my disappointment is one of the places that has a 1205*F Silver braze that they call "Silver Solder". They should know better.
All of them require temperatures above 1095*F to melt and some of them go as high as over 1800*F.
The 1095*F is just a few degrees below the melting point of Aluminum and the 1800*F temperature is well into the temperature range used for carborizing and hardening many steels.
The use of these brazing alloys requires a oxyacetylene torch as a minimum and special controlled atmosphere furnaces are preferred.
IMO, none of these silver brazing alloys should be used by a novice like me on a gun because of the difficulty of heating the part, the distortion or warping of the part and the possibility of having the braze alloy contaminated by air or oxides.
People who are advanced welders will know how to work with these alloys but folks like me would be advised to leave them alone.
That doesn't mean that the silver braze alloys are not used on guns.
The big factories who have the specialized equipment often use them to silver braze double barreled guns barrels, ribs and other items that require exceptionally high strength brazes.
Using silver braze also allows the barrels to be heated for the low temperature regular or silver solders without the danger of melting the barrel joint at later stages of the manufacturing processes.
I hope this helps someone get a feel for the various solders and the temperatures required to work with them.
paulvallandigham
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Thanks, Jim, for clarifying the issue of silver " solders". The stuff I used more than 20 years was the kind that melted in the 500 degree range. It was about too hot for a propane torch, to do a good job. Dad used a butane torch to heat the stuff up for jewelry he was making, but this work involves much less solder than would be used to mount hangers or pipes.
When the comment was made about using High temperature silver solder, I made the mistake of believing what Brownell's offers in its catalog, and that is the stuff you refer to here as Brazing material. You are obviously right. All I knew, and have known since I was a Cubscout, was that to get that kind of temperature, you had to use that Oxy-acetylene torch. I don't know now if that material was around back when Dad was still alive and using silver solders on various projects. I can't think of anything he was working on that would require being Brazed with anything.
You post tells the whole story. Dad never gave us the exact melting temperatures of the solders- both lead, and silver-- that he was using. He showed us how it was done. Then he had us show him that we could follow his technique and do it ourselves. You post tells me why he was not concerned about bending barrels, or other tubes that he was working on, and why wet rags served him so well as heat sinks.
I do remember that he once put a wet rag down a tube to cool the inside of a barrel, as a " precaution" against the tube warping or stretching. It worked. I saw something done like that on TV more than 40 years later in one of the shows on modifying cars, or motorcycles. The commentator didn't do a good job of explaining why they were putting a wet rag inside a pipe, but I recognized the technique immediately, and knew why they were doing it.
Thanks for the very fine, and very thorough post. :hmm: :thumbsup: :thumbsup: :hatsoff:
When the comment was made about using High temperature silver solder, I made the mistake of believing what Brownell's offers in its catalog, and that is the stuff you refer to here as Brazing material. You are obviously right. All I knew, and have known since I was a Cubscout, was that to get that kind of temperature, you had to use that Oxy-acetylene torch. I don't know now if that material was around back when Dad was still alive and using silver solders on various projects. I can't think of anything he was working on that would require being Brazed with anything.
You post tells the whole story. Dad never gave us the exact melting temperatures of the solders- both lead, and silver-- that he was using. He showed us how it was done. Then he had us show him that we could follow his technique and do it ourselves. You post tells me why he was not concerned about bending barrels, or other tubes that he was working on, and why wet rags served him so well as heat sinks.
I do remember that he once put a wet rag down a tube to cool the inside of a barrel, as a " precaution" against the tube warping or stretching. It worked. I saw something done like that on TV more than 40 years later in one of the shows on modifying cars, or motorcycles. The commentator didn't do a good job of explaining why they were putting a wet rag inside a pipe, but I recognized the technique immediately, and knew why they were doing it.
Thanks for the very fine, and very thorough post. :hmm: :thumbsup: :thumbsup: :hatsoff:
Thanks Zonie for the insight on materials and temp's. This was some of my hesitation to begining my project and attempting soldering instead of dovetailing them in.
So bassicly Propain temps wont expand the metal beyond reuturn at air cooling and 2 to 4% silver has yeilding strenght needed for lugs to hold together?
So bassicly Propain temps wont expand the metal beyond reuturn at air cooling and 2 to 4% silver has yeilding strenght needed for lugs to hold together?
You are correct about the expansion of the metal.
This is not to say that some residual stresses won't be released.
The boring, reaming and rifling process does produce some small stresses in the barrel and soldering temperatures will allow these to relax.
The net effect however is so small that one would need very fancy equipment to measure the barrel before and after soldering to see any difference.
The differences found would be so small that they won't effect the accuracy of the barrel.
As for barrel underlugs being simply soldered to the barrel, that is another issue.
As I'm sure you know, the strength of a soldered joint depends on the strength of the solder and even more on the surface area in the joint.
If, for instance you made an underlug out of a piece of 1/16 inch wire formed into a U with just the ends of the U soldered to the barrel flat the total area of the two contacting ends would be 0.0078 sq. in. If the solder had a strength of lets say 5,000 psi (I picked that number out of the air. It doesn't represent any particular solder), the strength of the joint would be .0078 x 5000 = 39.06 pounds. Much to small of a value to work.
If the underlug was formed out of a piece of bar stock that was 1/8 inch wide X 1/2 inch long and 3/16 tall the 1/8 X 1/2 inch sitting on the barrel would have a contact area of .0625 square inches. This with the 5,000 PSI solder would produce a joint strength of .0625 X 5000 = 312 pounds. Better but still not ideal.
If the base of the underlug measured 5/16 wide X 1/2 long the area would be .156 sq in and the 5,000 psi solder would produce a joint strength of .156 X 5000 = 781 pounds which IMO should be strong enough to take any loads applied to it by the barrel pin or wedge.
Personally I like to use the stapled underlugs and then after staking them in place I silver solder the joint.
Getting back to solder, I don't have any strength values at hand but silver solder is much stronger than a lead/tin solder so it is the thing to use in joints that are subject to moderately high stresses.
This is not to say that some residual stresses won't be released.
The boring, reaming and rifling process does produce some small stresses in the barrel and soldering temperatures will allow these to relax.
The net effect however is so small that one would need very fancy equipment to measure the barrel before and after soldering to see any difference.
The differences found would be so small that they won't effect the accuracy of the barrel.
As for barrel underlugs being simply soldered to the barrel, that is another issue.
As I'm sure you know, the strength of a soldered joint depends on the strength of the solder and even more on the surface area in the joint.
If, for instance you made an underlug out of a piece of 1/16 inch wire formed into a U with just the ends of the U soldered to the barrel flat the total area of the two contacting ends would be 0.0078 sq. in. If the solder had a strength of lets say 5,000 psi (I picked that number out of the air. It doesn't represent any particular solder), the strength of the joint would be .0078 x 5000 = 39.06 pounds. Much to small of a value to work.
If the underlug was formed out of a piece of bar stock that was 1/8 inch wide X 1/2 inch long and 3/16 tall the 1/8 X 1/2 inch sitting on the barrel would have a contact area of .0625 square inches. This with the 5,000 PSI solder would produce a joint strength of .0625 X 5000 = 312 pounds. Better but still not ideal.
If the base of the underlug measured 5/16 wide X 1/2 long the area would be .156 sq in and the 5,000 psi solder would produce a joint strength of .156 X 5000 = 781 pounds which IMO should be strong enough to take any loads applied to it by the barrel pin or wedge.
Personally I like to use the stapled underlugs and then after staking them in place I silver solder the joint.
Getting back to solder, I don't have any strength values at hand but silver solder is much stronger than a lead/tin solder so it is the thing to use in joints that are subject to moderately high stresses.
Use stay bright solder. Get it from Midway.
Stay bright is 5 times stronger than regular soft solder.
Stay-Brite® Properties:
Stay-Brite® Properties:
Composition tin & silver Composition tin & silver
Solidus (melting point) 430°F Solidus (melting point) 430°F
Liquidus (completely fluid) 430°F Liquidus (completely fluid) 535°F
Shear strength, copper sleeve joint in tension 14,000 psi Plastic range 105°F
Elongation 48% Shear strength, copper sleeve joint in tension 15,000 psi
Electrical conductivity 16.4 Elongation 48%
Color bright silver Electrical conductivity 17.1
Color
Stay bright is 5 times stronger than regular soft solder.
Stay-Brite® Properties:
Stay-Brite® Properties:
Composition tin & silver Composition tin & silver
Solidus (melting point) 430°F Solidus (melting point) 430°F
Liquidus (completely fluid) 430°F Liquidus (completely fluid) 535°F
Shear strength, copper sleeve joint in tension 14,000 psi Plastic range 105°F
Elongation 48% Shear strength, copper sleeve joint in tension 15,000 psi
Electrical conductivity 16.4 Elongation 48%
Color bright silver Electrical conductivity 17.1
Color
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I managed to solder the new underlug on without any trouble. Thanks for the very educational discussion! Fwiw I'm using 98% tin / 2% silver and it melts very easy. Long before the brass even thinks about changing color let alone the barrel.
