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Discussion Starter · #1 ·
Gents, I have the opportunity to return some K98's back to functioning rifles if I can just learn to solder the sights back on. In ALL my years of wrenching and WECSCOG'ing, Ive never gotten a good feel for this. Im trying to do this with COMMON tools and not invest in soldering pastes and voodoo.

Heres what I have access too: regular propane plumbing torch, MAPP torch, Home Depot 'silver' metal work solder.

I tried tonight. Heres my results:

First try: After 60 seconds of heat, solder just balled off and hit the floor.
So, I cleaned everything off with sandpaper and used some plumbing flux
Second try: After about 60 seconds of propane heat, I hit the solder..it seemed to flow but just for a second.

Third try: applied more flux. At this point the flux was kind of making a bubbly mess and the solder just balled off again.

So...WHAT am I doing wrong? Can this be accomplished with plain old HD tools and supplies?
 

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It can, had to replace my front sight on my reproduction enfield 1853. Removing tight bayonet give it a tap with palm .....and there goes the front sight. If its balling off the metal is not hot enough, when hot enough the touching solder to metal the solder should flow without the torch on it. Try not to put the torch right on it. Back it up so just the tail of the flame on it. Just takes patience and cussing. Took a while to solder my triple tree on one of my G3 projects. There is a lot of steel to wick heat away from where you want it soldered. If you have the barrel clamped make sure the clamp is back from area you are heating or it will steal the heat and act as a sink
 

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buy yourself some swif solder paste. all you do is apply the paste to the parts, position the parts and heat until you see silver then cool.
I wire parts in position so I can do more than 1 part at a time. swif paste works good. I have used it for water jackets and sideplates. saves time and frustration
 

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Discussion Starter · #4 ·
buy yourself some swif solder paste. all you do is apply the paste to the parts, position the parts and heat until you see silver then cool.
I wire parts in position so I can do more than 1 part at a time. swif paste works good. I have used it for water jackets and sideplates. saves time and frustration
WHY YOU NO READ POST?? I DONT want to go buying pastes. (But now that Ive yelled at you, let me explain why) Years ago I bought some silver solder paste from Brownells. **** was crazy expensive, IIRC like 30 bucks for a 1 ounce tub. (throw in shipping and its now around 45 dollars)
I used it twice (with great results) and put it away. A year or two later I opened it up again and it was caked solid, totally dried out and worthless.

Im assuming the SWIF paste will do the same? Oh well, Im off to Google land to check it out anyways, it sounds like a better plan than what Im currently doing.

EDIT: Utilized my Google-fu. SWIF paste appears to be discontinued and its replacement, Hercules, is 45 bucks a tub.

Looks like Im back to Home Depot sourced supplies.

So Gulf, you say its a heating issue?
 

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What I like to do is prepare the metal as best you can the coat it in flux. Use a torch or a very large iron to boil the flux off the metal, then immediately apply more flux. FWIW water soluble is easier to clean up but the non-water borne tends to work better. After the second layer is applied heat it again until it is good and hot the flux will start to boil again, take your solder and touch it to the metal. If it sticks great if not keep heating. It really is a matter of heat and using the flux to clean the metal.
 

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Are you soldering on front sights, rear sights, or both? Are we talking about mil-spec K98 sights or some other kind?
 

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Im trying to do this with COMMON tools and not invest in soldering pastes and voodoo.
I'd never done any silver soldering before and had some parts to put on a piece. Like you I didn't want to buy a bunch of stuff that I hardly ever use.
See attached video:
https://www.youtube.com/watch?v=T2wYgQtPg4g

It helped me get started. The first time I was successful, the second part was a little bigger and I flubbed it. It's one of those learning through experience things I guess. Just don't give up. One thing about silver solder flux is that it has a relatively short shelf life. About a year I think, maybe less. Also the mating surfaces have to be totally clean. I brushed my surfaces using a dremel with a wire brush. Not really motivating to use if your worried about blueing or park finish.
 

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ScottD--

I have rebuilt and rebarreled several K98 Mausers as well. I have found that with modern materials the use of silver solder is unnecessary. After aligning up the rear and front sight on the new barrel. I use a center punch for alignment. I use Loctite 680 to set the sight bases in place. Its a lot cleaner. Loctite 680 is used by several AR platform builders for setting the FSB to the barrel. That stuff is high temperature and tough.

Cheers

--fjruple
 

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The flux you find at home depot is best for non ferrois metals. It works poorly or not at all on steel. The "silver solder" found at home depot is regualr soft solder with a little silver in it. IMHO not that big a deal. True high temp silver solders come in many diferent alloys. Some flow better or bridge gaps better then others and at diferrent temperatures. It can be VERY strong. These require special flux as well that is diferent from soft solders. K 98 rear sight collars were soft soldered on. With the proper flux for steel they are a breese to instal. There is alot of surface area so soft solder is plenty strong. They make a some high strenth soft solders which would be good for front sight ramps as you have less surface area to grab. I guess you could also use regualar soft solder but it will not be as strong. Now on to the pastes that you hate. They make some soft solder pastes that are a mix of ground up solder and the proper flux for steel. This is wonderfull stuff I have used it so solder in 22 barrel liners. You paint it on and then slowly heat the part. You can see the solder start to melt and turn silver you now are at the proper temperature. No need to add more heat at this time just maintain. You can now add some more solder if you like and it will wick right in. I have had the same tub of solder paste for years when it starts to dry out I ad a little water and stir. I would bet your tube of silver solder is water based as well. Try putting it in a small bottle and add a little water and see what hapends. Soldering steel is not too hard just make sure it is 100% clean, use the corret flux (or solder paste) and add the heat slowly. Do not overheat it.
Dave
 

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Flux :Boric acid and Isopropyl alcohol both from your local pharmacy :rolleyes: makes an all temperature silver solder flux from EZ to Hard silver solder .
 

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Hey, Dave -- you're pretty good, for an "apprentice!"
:drink: (+1 for what he said.)

Carry On,
Gary
><>
 

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ScottD--

I have rebuilt and rebarreled several K98 Mausers as well. I have found that with modern materials the use of silver solder is unnecessary. After aligning up the rear and front sight on the new barrel. I use a center punch for alignment. I use Loctite 680 to set the sight bases in place. Its a lot cleaner. Loctite 680 is used by several AR platform builders for setting the FSB to the barrel. That stuff is high temperature and tough.

Cheers

--fjruple
Bingo! That is where I was going with the question about whether you are using military sights. Since both front and rear sights mount with barrel rings Loctite is easy and almost as good as silver solder. Just be sure the barrel and sight rings are clean and you have a system to keep everything in the twelve o'clock position.
 

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As mentioned, traditional silver-solder fluxes are borax and some liquids (water, alcohol), so when they dry out, it's perfectly fine to re-hydrate them and keep using.

As for the HD stuff, it's got so little silver in it as to be for marketing only. It'll work like any other soft solder. Key there is to clean everything down to bare metal and keep the flame off both the flux and solder. Use flux for ferrous metal if at all possible.
 

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Discussion Starter · #14 ·
So ive learned to keep the flame off the solder. That alone may be enough to point me in the right direction.

My intention is to not only fix/restore my friends K98's, but to become more acquainted with a skill thats quickly loosing fashion. Last week I made a mess of a front sight on a project gun because I brazed instead of soldered. I want to be able to do things the right way, for personal satisfaction if nothing else.
 

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Solder with the wrong flux will make it bead like rain on a newly waxed car. See this 'shot in the dark' web search for an idea of what's out there:

http://www.superiorflux.com/industrial_soldering_flux_overview.html

Plumbers are stuck with 95/5

Tinsmiths like 50/50

There are more silver alloy solders and brazing flavors than ice cream at baskin robins.

If the base metal is near the temp of the melting point of the solder, it'll flow and stick with the right flux.
 

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Forgot to add that Capillary action is your friend. Watch a pro plumber and they'll put heat to the center of the joint, touching the solder to the pipe ahead of the joint once in a while to see if it's hot enough to melt the solder. Once it flows, they'll pull the torch back and feed the solder into the joint whereupon it'll wick all the way around and into the socket. The heat pulls it in and the results are a nice, tidy joint.

B-D
 

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Get the right flux and practice on some scrap steel. That way when you need to do it on the real deal you have some experience. Just as with shooting, welding and many other things, you can read all the books you want but it take practice to hone your skills.
Happy Soldering
Dave.
 

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A couple things that may help...

Solder flows towards the heat.

Preheating can make it easier. Doesn't have to be red hot.

E
 

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And when plumbing you use a wet hand towel sized cloth to wipe away the excess solder to leave a clean joint. So if you get too much around the base its a nice way to clean it up.
 

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Discussion Starter · #20 ·
Probably the biggest mistake people make is heating the solder and the small part. You apply heat to the part with the greatest mass and when it's hot the heat will transfer to the smaller part. A barrel is a large mass and will not heat quickly. I wouldn't use anything other than propane on a barrel since Mapp should only be used when you know what you are doing....it's a lot hotter than propane. Same thing in plumbing, beginners heat the pipe, experienced folks heat the fitting since they are always thicker than the pipe and thus have more mass, holding the heat longer and the heat transfers to thinner pipe and draws in the solder when it's up to temp. You heat the localized area, not a point area so the heat distributes more evenly vs. getting cherry red in one area which is not the desired outcome. I wipe with a dry cloth or paper towel because I don't mind the joint cooling slower and it looks nicer than a wet wipe....unless I'm in a hurry. If you've repeated this more than a couple times the solder joint requires a lot more cleaning each time to make it work and flow well. Your first shot will be the best. Three times on copper fitting and I throw it away if I haven't succeeded. Rare these days, but if you work on a lot of wet lines, it happens. I'd use crap plumbing solder which is easier to work with. I still use it on A/C lines with over 350 psi spikes and have never had a leak or failure in over 25 years. The stronger the solder and higher melting point (like silvers) the harder it is to work with. HTH
So will regular plumbing solder will work for general gunsmithing?
 
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