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Posted: 12/4/2012 3:37:02 PM EDT
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I'm trying in vain to silver solder several muzzle devices onto threaded barrels.
I've got an Oxy/MAP torch and get the flame to what the manual says is a good flame for soldering. Seems to be extremely hot and shows no soot at the end of the flame. I've cleaned the threads extensivly with a brush and brake cleaner followed by blowing clean with dry compressed air. I paste the threads with 1200 degree silver solder and thread the device on. It pushes a small lip of solder with it. I pack the barrel with heat block as well as coating the barrel and the part of the muzzle device that isn't over the threads. I heat the exposed metal till I see it glowing red and keep the heat on for a few minutes. The device seems to be set after it cools down, but upon shooting, it breaks free and becomes obvious that I did something wrong. One thing I notice is that while I'm torching, the exposed metal builds up a layer of what looks like carbon around it. This carbon may be what I see glowing read and it's insulating the metal from heating up. Any suggestions? I hate to waste any more Oxy and silver solder and trips to the range just to find out I've once again failed. Thanks in advance. |
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You are way to hot if you are heating to glowing red. You are burning off the flux and oxidizing the surface so nothing will stick.
Heat the metal until the solder flows (do not heat the solder in the flame, the solder will flow to the heat) Use just enough heat to melt and start to flow the solder then move the heat away Keep the solder about 1/4" or a little more away from the flame |
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I'm definitely heating the work and not the solder as the solder is in the threads between the muzzle device and barrel. I'm guessing I just need to watch the small lip of solder that the device pushes and stop when it starts to flow. The solder I'm using is a pre-mix with flux included.
Silver Solder From Otto Frei I''ll give it another go tonight. |
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Why not just use Rocksett thread locker?
http://www.brownells.com/gunsmith-tools-supplies/general-gunsmith-tools/thread-locking-liquids/rocksett-prod54624.aspx brownells # 100-010-681WB Incredible temperature resistance, -350 degrees F up to 2,015 degrees F Intended for use on threads an cylindrical assemblies (flash hiders & muzzle brakes) In addition to acting as an adhesive, Rocksett acts vibration dampening material Non-toxic, odorless, and non-flammable Withstands oils, fuils, acids, and alkalis Long shelf life No mixing or priming required Bonds ceramic, glass, and metals Surfaces to be bonded should be dry and grease free Ships in a 2oz bottle Benefits: Extremely high temperature range makes Rocksett ideal for attaching muzzle devices Several suppressor manufacturers use Rocksett to ensure that muzzle devices to not loosen when used in conjunction with a suppressor |
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Quoted:
Why not just use Rocksett thread locker? http://www.brownells.com/gunsmith-tools-supplies/general-gunsmith-tools/thread-locking-liquids/rocksett-prod54624.aspx brownells # 100-010-681WB Depends on the reason he's using high temp silver solder. Most smiths who use high temp silver solder are doing so to meet "permanent attachment" criteria set by the ATF to avoid creating an SBR. Rocksett is not an ATF-approved permanent attachment method. OP, if the outside of the muzzle device is glowing dull red, the interior's too cold. You need to get the outside warm orange to be getting 1200 inside at the joint. |
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Quoted:
You are way to hot if you are heating to glowing red. You are burning off the flux and oxidizing the surface so nothing will stick. Heat the metal until the solder flows (do not heat the solder in the flame, the solder will flow to the heat) Use just enough heat to melt and start to flow the solder then move the heat away Keep the solder about 1/4" or a little more away from the flame "Silver Solder" is actually more like a brazing process. AWS defines soldering as <700F and brazing >700F. Silver solder is 1100-1200F |
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Maybe these pictures will help identify what I am doing wrong.
I tried not heating it near as long, no success. I keep the flame on the muzzle device in the area of the threads. I have soldered electronics so I understand heating the work and not the solder. I stopped when I thought I saw a change in the ring of solder/flux, still didn't work. I used a bronze / copper brush to clean the threads. Any chance this is contaminating the joint? Solder on the threads 
Ring of solder after threading and indexing 
Flame I have been using 
Heating the device 
Layer of carbon when I'm done 
Results after failure 
Rocksett isn't going to work. I need the length of the device for overall barrel lenght. Thanks for the suggestions so far. If anyone is in the Charleston area, I'll pay you to come teach me to do this!! |
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The other point I can make is when you have a short fairly lightweight part (the f;ash hider) and a heavy long part (barrel) the light part will get to temperature and the heavy part will not heat up near as fast. You need to heat mostly from the barrel side (say 75% of the time) to get both parts at the same heat so the stlver solder will flow to both parts.
Also I haven't used the flux solder mix but typically the flux changes and flows at a lower temp than the Silver. Basically you need even heat in a limited range that the solder works at |
| A phosphated/oxided surface will not take soldier. You need to media blast the threads, A and B, with AO to properly prep the parts. A small hole (1/16) has to be drilled in the muzzle device at 6 and 12 o'clock through the wrench flats. These are used to deposit solder. Without the holes, there is no way to get enough solder into the threads to prevent cold removal of the muzzle device. |
| yep, not enough heat, you have a large barrel sapping heat from the spot your working on, it will take a LOT of torch time to get the barrel to temp, also glowing red is a bit hot for 1200 silver solder, best turn down the lights so you can see the color change as it just begins to glow a faint dull, dark red which is around the temperature you want for soldering. |
| Bronze/brass brush should not be used. If using a wire brush, a stainless brush should be used. That black soot buildup makes it look like you're not getting nearly hot enough, that's not soot from oxidizing metal, that's soot from your fuel gas. Combination flux/paste solders are crap, in my experience. Stay Silv flux and some true leaf or wire silver solder and you wouldn't even need to sweat into the threads, simply sweating the joint between the shoulder of the muzzle and the face of the muzzle device would be sufficient. |
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Quoted:
All of the above are a good argument for pinning and TIG. Much less invasive. I really don't enjoy putting that much heat into a muzzle not to mention for me the pin/tig is faster and leaves less finish work. Aaaaand we're off! Posted Via AR15.Com Mobile |
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pin and tig your flame should be blue not yellow blue, you have it too hot and you need to have a longer muzzle device as it should look like threaded in place. then you need stay silv flux  heat the muzzle brake up while moving the heat around slowly lightly touch the 15% silver solder to the part where the threads touch the brake. but if you are trying to put that brake on with that little amount of threads into the brake you will always have trouble |
| yup, your flame is wrong. I only use oxy acetalene for that much bulk. You have to bring it around to an orange on very clean fluxed threads. you will know when you hit the right temp And to varify, touch the joint with silver solder wire and see it suck right into the joint. Then you know your home. Also, you must let the peice air cool slowly! do not quench!! or you will end up with a brittle barrel. |
| I have never used map gas but if that was a oxy-acetylene torch the flame you are showing would be a carburizing flame (fuel rich) should be adjusted so there is a small sharp blue cone right at the torch tip .The fuel rich flame is why you have soot with a properly adjusted flame you will have no soot. also the tip size would be important you need one to heat your metal quickly. |
| I have found that those oxy/map tourches get hot but the flame is not big enough to put heat on a larger area like a barrel or copper pipe over 1/2 inch. Try a straight map gas torch. Better yet a turbo torch http://victortechnologies.com/turbotorch/products/detailProduct.html?prodID=0386-1283 That is only if you dont have access to a full size torch set. |
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You have probably heated / cooled so many times that the metal is breaking down (scale).
Now, Clean everything off and use a file to get the connecting areas down to the base metal. Prior to assembling, "butter" the area to be joined with a thin layer of silver solder. This means take bare (filed shiny) metal, apply higher temp flux, heat to proper temp and apply a small amount of silver. let it cool, brush it off and assemble with new flux. Now, all you have to do is to heat it enough to make the 'buttered" area melt and feed in a bit more silver solder. If this fails ..... Clean everything off and have it TIG welded together. Hobo |
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