Trying to braze for the first time.

[John 242]

While detail cleaning my Yugoslav M24/47, I was fiddling with the rear sight when the flat spring broke. I had rocked the rear sight all the way forward and apparently, that was too much stress for the 60+ year old spring.

Let me preface the following by saying that my experience at soldiering things together has been little and usually with poor results. The only success I’ve had was when I recently fixed a metal candle stand for my wife.

Figuring that I had nothing to lose, I grabbed up my torch, flux paste and a little bit of tin solder and headed to the garage. I cleaned the bluing off the area around the break with some sand paper, with hopes to get the soldier to stick. I then put a heavy coat of flux on the two pieces. I was using a small magnet to hold the two pieces together, which really didn’t work very well. I sparked the torch and laid a bead of solder on the joint. The soldier actually stuck to the two pieces surprisingly well and even flowed into the joint. Unfortunately, but probably expectantly, the tin soldier failed when the rear sight was installed onto the spring. Tin just doesn’t have enough strength for this application.

I jumped into the car and headed to the Tractor Supply (TSC) to see if they had anything useful. I picked up what I thought might be silver soldier (it says “silver” on the package) and some bronze brazing rods.
I repeated the above procedure with the ‘silver’ solder and was able to get it to stick. Again, unfortunately, the joint broke. I’m not sure if the solder or my technique (or lack thereof) was to blame.

At this point, I figured I’d give the bronze brazing rod a try. I cleaned up the two parts, fluxed them with the same flux and broke out the map gas cylinder for my torch (I don’t have a oxy/acetylene torch). I held the parts by very careful placement in a set of vice grips held in a vise. I heated the two parts red as best I could and applied the rod. For the most part, the bronze pooled in a ball and fell off the parts when cooled. I figured that the parts weren’t hot enough so I cleaned them up and repeated the process, again and again. Eventually, I was able to get a large ‘blob’ of bronze to stick to the larger of the parts, but with zero penetration into the joint. When cool, the smaller of the two pieces remained unattached.

I had to go to work, (I work overnight) so I gave it a rest and ordered two springs (one as a spare) from Numrich for about $5.00 (I had spent 5-times that on the solder and brazing rods). I haven’t messed with the spring pieces since due to work and other priorities.

Although not successful, I did learn a little bit and had fun with this little experiment.
Trying to solder or braze a spring together might not be the smartest idea, especially when they cost $2.
I suck at brazing.

I don’t know if soldering flux is the right thing to use when brazing with a bronze rod, but it's all I had.

Anyway, I thought I'd share and see what you all have to say. Poking fun is alright, but have some mercy.
http://castboolits.gunloads.com/imagehosting/thum_153350178db9da29e.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=6099)

[Mooseman]

Lesson Learned...Springs cannot be brazed or soldered. The High carbon content of the steel and the tempering are all factors and when you heat a spring you lose the temper and it must be retempered.
Buy a new spring and quit fooling around ! LOL
You spent more in gas than the spring costs.
Rich

[John 242]

Lesson Learned...Springs cannot be brazed or soldered. The High carbon content of the steel and the tempering are all factors and when you heat a spring you lose the temper and it must be retempered.
Buy a new spring and quit fooling around ! LOL
You spent more in gas than the spring costs.
Rich

(Laughing quite loudly) Yeah, yeah...
Tempering was an after thought, but roger that. Heck, I was pretty happy with just sticking the two pieces together with solder... until they broke again.

Phase II may be buying or scrounging some flat carbon steel and seeing if I could make a useable spring out if it. More gas, etc, etc. (still laughing).

[Bret4207]

Don't feel bad. I'm trying to re-learn steel soldering. Used to do it all the time. Now I weld or braze everything. But I need to solder some stuff now. It's different!

[Goatwhiskers]

Makes me think of a few years ago when I took in a M11 Rem shotgun to make functional again--was Grampaw's old gun in the closet. The main spring was laying flat in the trigger group, supposed to be arched. Looked closer, it had broken and was brazed back together. I guess a country boy will survive, or try to. Goat

[seagiant]

Hi,
If you want to learn,you could get a piece of spring steel the right thickness and make a new spring! This would teach you hardening and tempering. With this thin steel you could do all the operations on a kitchen stove!

Of course ordering a new spring would be easier and if you are married less life threatening!!! Ask me how I know!

[Hardcast416taylor]

I can`t put a number on the times I had taught people to solder copper pipe when I was employed as a plumber. For some reason nobody wanted to show these people the ways of soldering, like some kind of Masonic lodge secret or some such foolishness. Within 10 minutes I could have people do soldering nearly as well as I can.[smilie=w:Robert

[John 242]

Hi,
If you want to learn,you could get a piece of spring steel the right thickness and make a new spring! This would teach you hardening and tempering. With this thin steel you could do all the operations on a kitchen stove!

Of course ordering a new spring would be easier and if you are married less life threatening!!! Ask me how I know!

I'm seriously considering making my own spring, just to see if I can make one that works. There are some really great videos put out by Midway, where Larry Potterfield makes a few springs, but the details are a little sketchy. I'm pretty sure 1018 won't work since there's not a lot of carbon in it. Have to do a little research.

We have one of those electric stoves with the glass top, but I do have my torch, turkey frier and a camp stove that I can do some serious damage with. One day I'll have a heat treating oven... one day (sad).

By the way, that's a nifty looking hammer. Boy, I could really smash my fingers with that thing! Looks like a cool project. Build it from scratch?

[seagiant]

Hi,
I blacksmith for a hobby and owned a Little Giant 25lb hammer for years making my own pattern welded steel for knives. That hammer is called a "Tire Hammer" amnd is home made. There are plans available from Clay Spencer. I don't have a hammer now as I progressed to machining and bought a BP mill.

The spring is no problem and can be tempered using the temper color chart. After hardening can be clened sanded to bright metal then held over the heat until blue. Easy really. It's also quite gratifying!

[xd4584]

I heated the two parts red as best I could and applied the rod. For the most part, the bronze pooled in a ball and fell off the parts when cooled.

Steel should not turn red when being soldered. Thats why the solder balled up and rolled off, the steel was too hot. If you are using a wipe on flux you can usually go off that. When it starts to look like glass the metal should be hot enough.

But everyone else is correct. You cannot heat a spring or you will ruin it, then you have to go through the tempering process again, which sometimes if you over heat it, you might not be able to fix it.

[Bret4207]

My problem is most of the steel I want to solder is rusted. You can't solder to rust! I finally patched the oiler I was working on today by soldering a copper patch over it. Looks awful, works great.

[John 242]

Steel should not turn red when being soldered. Thats why the solder balled up and rolled off, the steel was too hot. If you are using a wipe on flux you can usually go off that. When it starts to look like glass the metal should be hot enough.

But everyone else is correct. You cannot heat a spring or you will ruin it, then you have to go through the tempering process again, which sometimes if you over heat it, you might not be able to fix it.


Thank you for the advice on over-heating. I'll remember that when I try again on something else.


My problem is most of the steel I want to solder is rusted. You can't solder to rust! I finally patched the oiler I was working on today by soldering a copper patch over it. Looks awful, works great.
(laughing) Yeah, if it works, it works.
I've always been kind of afraid to leave my comfort zone, so experimenting like this can be a challenge. Posting my lack of success and ignorance on this forum, even more so. I've learned a bit from you guys and I appreciate it.

[Plinkster]

Also I'm not sure what brazing rod you got but if it has a white coating on it, it needs no paste flux. That coating is the flux, if it's bare brass that's different and you will need flux.

[rbuck351]

When your brazing and the broze rod balls up it's because it's not hot enough. The bronze will start to boil when you are to hot. When soldering, get the part just hot enough for the solder to melt when it is touched to the work piece. You have found that although you can solder a spring, it will break at the joint. Getting it hot enough to braze and the temper is gone. It is fun learning this stuff the hard way. Not that I have ever tried anything like that.[smilie=1:

[xd4584]

When your brazing and the broze rod balls up it's because it's not hot enough.

I'm not sure about that. I don't use bronze. I work in HVAC and we use silver solder for steel. When I took my test I was shown was will happen if you get steel to start glowing. The braze is no good. I have also had the wrong type of wire on steel and it will ball up and roll off. I am not sure what it was, I got it from a guy I work with and he thought it was silver solder...

[Bret4207]

Rbucks right a the braze balling up, not hot enough. Braze requires about a bright red to dark orange heat, then the braze melts right into the work (descriptive term) as long as it's clean enough. If it's not clean t he braze falls off. If it's clean but not hot enough the braze balls up and semi sticks.

I've got a zillion hours brazing back when thats how we did body work.

[John 242]

Rbucks right a the braze balling up, not hot enough. Braze requires about a bright red to dark orange heat, then the braze melts right into the work (descriptive term) as long as it's clean enough. If it's not clean t he braze falls off. If it's clean but not hot enough the braze balls up and semi sticks.

I've got a zillion hours brazing back when thats how we did body work.

That's what was happening. Some would ball up and semi-stick while on other attempts it would simply fall off.

No doubt my temperature was wrong and the parts probably weren't clean enough, either.
Using a Map gas torch probably contributed to the problems, but my lack of technique is really the biggest issue. A little study and a lot of hands on will fix that.

I've learned a little bit about brazing from goofing around and from you guys, so it was worth it.

[R.M.]

Did you get all, and I do mean all of the lead solder off before you tried brazing? If you didn't, you'll never have any luck getting the braze to flow.

[theperfessor]

Just to offer a couple technical points:

Soldering uses a filler metal that melts at temperatures below 800F. Brazing uses a filler metal that melts at temperatures above 800F. In neither case should the base metal melt, but in both cases the base metal must be hot enough for the filler metal to bond as a liquid to the surface of the base metal.

Since most ferrous metals begin to soften at temperatures above 400F, it is easy understand why steel parts can be soldered with minimal loss of strength using solders that melt in the 400-600F range, but that brazing always causes steel to lose it's hardness and strength by causing a conversion of the hard microstructure (martensite) into a soft microstructure (ferrite).

I don't braze much, but I was never successful when I tried until I got things very clean and thoroughly degreased and used the right flux. Then things worked well, the brazing filler metal would just seem to be sucked into the joint by capillary action.

[wallenba]

Numrich has your part I think, here> http://www.gunpartscorp.com/catalog/Products.aspx?catid=4204
Look on page three, part no. 729930

[scarry scarney]

BTW, AGI has videos on spring making

[John 242]

Removing the lead solder-
No, I probably could have done a better job of cleaning the parts and degreasing them.

Professor, thanks for that technical bit of information and advice.
I'm sure the flux I was using isn't intended for brazing. Unless you have a recommendation, I'll check out a couple of the on-line retailers like Enco and MSC for brazing flux. Brownells probably sells something, too.

I ordered two springs from Numrich and received them within a week. One looked brand new, while the other was hammered looking. The newer one fit fine and works well, the other seems to be a little 'fat'. That's okay, if I need it, I'll take an India stone to it.

I'd like to give brazing the broken spring one more shot because I'm really curious to see if I can get the pieces to stick together. We'll see.

[John 242]

BTW, AGI has videos on spring making

I'll bare that in mind. I've heard good and bad about the AGI videos. Have you seen this one?

[nanuk]

I was told by a hobby blacksmith, that to try my first attempt at a spring, get an old car rear leaf spring.... the content is about right

I've never tried it though...

any thoughts on that as a material?

[M-Tecs]

The most comon springs including leaf springs are 1086 and 1095.

[rbuck351]

The spring should be easy to braze if clean. But, when you get it brazed it won't be a spring anymore as that will take all the temper out of it. If you managed to get it retempered properly , then the bronze joint will be dead soft as the heat required to temper the steel will soften the bronze and it will break at the joint. The only way I think you could fix the broken spring would be to gas weld it back together using more of the same material as filler rod, grind it smooth and retemper it. A whole lot more work than makes any sense not to mention someone very talented. I.E. not me.
Once you learn how to solder or braze, both are fairly easy. The fluxes for solder and brazing are different and neither will work for the other.
An old car spring has good spring steel in it but it would some serious cutting grinding to get a piece small enough to make a sight spring. Non tempered spring steel can be bought in dimensions close to what you want and then filed or ground to shape and then tempered and drawn back to the right hardness. Still a lot more work than just buying a replacement unless you just can't get one.

[Bret4207]

Rbuck, sorry, but you have confused me with this line- "If you managed to get it retempered properly , then the bronze joint will be dead soft as the heat required to temper the steel will soften the bronze and it will break at the joint. " To the best of my knowledge bronze doesn't temper so what would reheating it do? I have seen examples of V springs made up of 2 pieces joined with bronze or silver solder. As long as the joint is maintained during tempering, it should be no issue. What am I missing?

[rbuck351]

Bronze doesn't temper as such but does work harden and will soften when heated. Temper was the wrong term. The point is that the heat needed to temper and or draw out temper in steel will soften bronze. The differential springyness of the two metals is a sure bet that when you try to bend the brazed spring, the joint will break. Even if you gas welded it using a different filler steel than the parent metal, it would very likely break at the joint. We are talking a butt joint that will have to bend in the joint as well as the rest of the spring. When the bronze in the joint starts to bend it will break. If you overlapped the spring so it didn't bend at the joint it could work but then it would be too short. A vee spring could be repaired if you filled in some at the bottom of the vee to prevent the joint from bending. If a soldered or brazed joint bends it will break. Bending spring steel puts a lot of load on the steel for its size. The softer metals will not stand the load needed to bend the steel if it is even close to the same thickness.

[MBTcustom]

I agree that you need to order another spring.
I disagree with the assertion that spring steel cannot be soldered.
I have soldered springs several times, (the hand spring in a single action revolver is one example) The trick is to use the right flux, and the right solder. If you use a low-heat solder, then you can sweat a spring in place and not damage it.

Most springs are made of carbon steel like a 1095 or similar. They are heated to 1550 degrees and oil quenched in order to harden them, but then they are drawn back at a temperature of about 700-800 degrees (hence the blue color) for the life of the spring, as long as that temperature is not exceeded, then the spring will still work.

The problem is that most folks don't use any finesse when applying heat to a spring.

First, you must have clean, ground, bare metal, that has been cleaned with soap and water. (Dish soap and water gets things cleaner than acetone and alcohol when it comes to common oils, trust me.)
Second, you cannot heat the filler material/solder. It must be melted by the parts being soldered.
Third, you cannot overheat the work piece, or it will burn the flux and you will never get the solder to sweat. Also, the spring will be ruined by the excessive heat.

The right way to do this, is to start by fixturing up the part to be soldered so that you can work with the torch and the solder without trying to keep thing lined up. Needle nosed vice grips are exceedingly useful for things like this.
Now, pre-heat the work piece.......gently.
Next apply the flux. The flux will tell you when you are close to the right temperature because it will start boiling.
Next, start dabbing the solder to the workpiece on the opposite side from the flame. Solder runs toward the heat source.
as soon as you see the solder start to melt, get off the heat! Just blush the torch over it enough to keep the solder just on the high-side of that critical eutectic point.

If you did it right, the solder will wick right where you want it to go like magic.

Brazing works the same way.

The priciples are all the same: Put the heat in the right place, and match it to your filler. Don't use too much heat, or too little.

One other tidbit I might add, that messes a lot of people up.
Any soldered or brazed joint is strongest when it is less than .001" thick but more than .0005". Every thousandth of an inch that the solder or braze has to fill, weakens the joint terribly. One of the ways that you get a darn good, strong joint, is by taking care that all the surfaces fit tight.

If I absolutely had to do a repair like is in the original photograph, I would grind a new piece of spring steel that would lay over the top of those two halves by at least .25 on either side. Then I would solder it together while it was held tight together.
Next I would carefully grind away the underside of the joint (the original spring) until the proper spring tension was achieved.
Then again, I would probably just use the original as a pattern to grind out a brand new spring!

Can it be soldered? certainly!
Should it? only after exhausting about ten other options that are easier and quicker! (ie, probably never!)

Here are some pictures of brazing and soldering:
I brazed this banded front sight together, but it warped from the heat, so I redid it with solder instead.
http://i1120.photobucket.com/albums/l481/goodsteel/IMG_3390.jpg
Here it is after soldering:
http://i1120.photobucket.com/albums/l481/goodsteel/IMG_3406.jpg
Here it is finished and installed, notice the absence of a solder line? It is less than .001 and cannot be seen:
http://i1120.photobucket.com/albums/l481/goodsteel/IMG_3413.jpg
http://i1120.photobucket.com/albums/l481/goodsteel/IMG_3423.jpg
http://i1120.photobucket.com/albums/l481/goodsteel/IMG_3425.jpg

[Bret4207]

Bronze doesn't temper as such but does work harden and will soften when heated. Temper was the wrong term. The point is that the heat needed to temper and or draw out temper in steel will soften bronze. The differential springyness of the two metals is a sure bet that when you try to bend the brazed spring, the joint will break. Even if you gas welded it using a different filler steel than the parent metal, it would very likely break at the joint. We are talking a butt joint that will have to bend in the joint as well as the rest of the spring. When the bronze in the joint starts to bend it will break. If you overlapped the spring so it didn't bend at the joint it could work but then it would be too short. A vee spring could be repaired if you filled in some at the bottom of the vee to prevent the joint from bending. If a soldered or brazed joint bends it will break. Bending spring steel puts a lot of load on the steel for its size. The softer metals will not stand the load needed to bend the steel if it is even close to the same thickness.

Okay, you had me confused. Repairing springs has never worked for me. Better to make a new one.

[Bret4207]

I agree that you need to order another spring.
I disagree with the assertion that spring steel cannot be soldered.
I have soldered springs several times, (the hand spring in a single action revolver is one example) The trick is to use the right flux, and the right solder. If you use a low-heat solder, then you can sweat a spring in place and not damage it.

Most springs are made of carbon steel like a 1095 or similar. They are heated to 1550 degrees and oil quenched in order to harden them, but then they are drawn back at a temperature of about 700-800 degrees (hence the blue color) for the life of the spring, as long as that temperature is not exceeded, then the spring will still work.

The problem is that most folks don't use any finesse when applying heat to a spring.

First, you must have clean, ground, bare metal, that has been cleaned with soap and water. (Dish soap and water gets things cleaner than acetone and alcohol when it comes to common oils, trust me.)
Second, you cannot heat the filler material/solder. It must be melted by the parts being soldered.
Third, you cannot overheat the work piece, or it will burn the flux and you will never get the solder to sweat. Also, the spring will be ruined by the excessive heat.

The right way to do this, is to start by fixturing up the part to be soldered so that you can work with the torch and the solder without trying to keep thing lined up. Needle nosed vice grips are exceedingly useful for things like this.
Now, pre-heat the work piece.......gently.
Next apply the flux. The flux will tell you when you are close to the right temperature because it will start boiling.
Next, start dabbing the solder to the workpiece on the opposite side from the flame. Solder runs toward the heat source.
as soon as you see the solder start to melt, get off the heat! Just blush the torch over it enough to keep the solder just on the high-side of that critical eutectic point.

If you did it right, the solder will wick right where you want it to go like magic.

Brazing works the same way.

The priciples are all the same: Put the heat in the right place, and match it to your filler. Don't use too much heat, or too little.

One other tidbit I might add, that messes a lot of people up.
Any soldered or brazed joint is strongest when it is less than .001" thick but more than .0005". Every thousandth of an inch that the solder or braze has to fill, weakens the joint terribly. One of the ways that you get a darn good, strong joint, is by taking care that all the surfaces fit tight.

If I absolutely had to do a repair like is in the original photograph, I would grind a new piece of spring steel that would lay over the top of those two halves by at least .25 on either side. Then I would solder it together while it was held tight together.
Next I would carefully grind away the underside of the joint (the original spring) until the proper spring tension was achieved.
Then again, I would probably just use the original as a pattern to grind out a brand new spring!

Can it be soldered? certainly!
Should it? only after exhausting about ten other options that are easier and quicker! (ie, probably never!)



GS, sweating and brazing these days are pretty archaic methods it seems. Back in the day Brownells used to make a very, very nice premixed, ground silver solder. Using that any fool could get a wonderful, very tight joint with little effort. I know any fool could do it because I did it a number of times!!! OTH, I've spent many, many hours brazing body panels together back when I was doing body work. The extra heat needed for brazing is part of the problem with getting good fit up. These days I understand they glue panels together! Got me. All I know for sure is that you need to stay in practice or you'll end up with a trashy job of anything like this you do.

[John 242]

I appreciate all the tips and info. Definitely helpful.

Goodsteel, thanks for a great bit of information, it is very helpful.

Brazing, welding, and even soldiering are all kind of voodoo to me since in the past I never really had a need to do it. You guys have given me some know how, now I need to develop some sort of technique. Practice makes perfect.

Bret, if I'm not mistaken, Brownells still sells that paste you were talking about.
Yep, right here;
Brownells web page- (http://www.brownells.com/.aspx/cid=0/k=silver+solder+paste/t=P/ksubmit=y/s_o=CalculatedAvgOverallReviewFormula+%28Descendin g%29/Products/All/search=silver_solder_paste)
I've seen it used in a video and it looks simple enough to use, but so does brazing until you try it (laughing).

The purpose of me messing with this spring was to see if I could learn something. Well, I know a lot more now than when I started.
Anyway, thanks again guys.

[seagiant]

Hi,
Beautiful work,Goodsteel! When I sail 3rd Engineer I am the ships Electrician and I have to keep the ships lights running. A lot of US Merchant vessels are long in the tooth and with limited parts you have to get creative! A lot of light fixtures are made of thin material and brazing is your only chance!

I was taught to braze by a Phillipino that was an actual artist with it! When I asked him how he got so good,he said in his village everyone was poor and if something broke there was no money for a new part so the old stuff had to be fixed!

[Longwood]

Draw heavy lines with a soft lead pencil along where you are brazing.
If you are careful, the brass or silver solder will not flow across it, and you will get a perfectly straight line.
I use only a high grade,,, AKA expensive, silver solder that has a high silver content.
It is the easiest to do a good job with and has a much lower melting temperature than straight brass.
I am not talking about the low strength plumbers solder with no brass in it.

[rbuck351]

Goodsteel is right , it could be soldered by scabbing another short piece of spring steel over the joint and keeping the temp under drawout temp and then grinding it thinner until the proper amoung of "spring" was left. But if you have a peice of flat spring steel you might as well grind out a new spring. It could be brazed the same way except you would then have to retemper because of the much higher temps required to braze. Some things just aren't worth the effort.

[Longwood]

You know you are pretty good at brazing when you can build up a piece of brass, with brass, and not burn out any of the zinc.

[Silver Eagle]

One thing to possibly note: Not all silver solders are created equal. There is still quite a bit of silver containing soft solder out there. It was one of the early lead free solders. This is not hard solder but, soft plumbing solder. I have also found out that it does not mix well with standard tin lead solder when making repairs.

Also, be sure to use the right flux that is compatible with both the solder and the work material.

Silver Eagle

[JIMinPHX]

As Silver Eagle says, silver solder varies. There is "silver bearing" solder that usually has only a few points of silver & is classified as a soft solder. Then there is true silver solder. The stuff that I used to use was 45% silver. That stuff is basically a braising rod. Most soft solders do not stick well to steel. I think that Brownells or Midway carries some specialty low temperature solders that do stick to steel. As I recall, the proper flux for standard 45% silver solder was fluorine salts of some sort. At least, that's what I used to use when working on 3,000psi helium manifolds for medical equipment.

I agree with most of what goodsteel said, with one small exception. I always applied my flux before preheating. I was taught that this helped to prevent surface oxidation. I never tried it his way. I only did what I was taught. Another thing that I was taught by an old timer was to use a carbonizing flame. That is a flame that has the gas mixture a little rich on the fuel & lean on the oxygen. On an oxy-acetylene torch, you get that by fiddling with the knobs. On a map gas torch, you get that by covering part of the vent holes with a piece of copper wire. Again, I only did it this one way, so I don't know what difference it actually makes.

[JIMinPHX]

I'll bare that in mind. I've heard good and bad about the AGI videos. Have you seen this one?

I've only seen 2 videos from AGI. They were about precision tuning factory rifles. I would have happily paid many hundred dollars for the factory rifle that the guy started with. I might be tempted to spend $50 for his end product, if I happened to need a few untouched parts off of it.

I have not seen their video on this subject.

[MBTcustom]

I apologize if I posted false information. I am self taught. Irregardless, you are toast if you burn your flux.

[JIMinPHX]

I apologize if I posted false information. I am self taught. Irregardless, you are toast if you burn your flux.

I'm not sure that my way is any better. I just had different information, so I thought that I would offer it.

Regards,
Jim