Soldering and brazing.

[GaryK]

I haven't done either of them and was wondering what the difference was.

I have a few questions.

What materials can you solder? What is the strength of the joints.

Same questions for brazing.

Can both be done the a propane torch?

Is there a special kind of solder needed?

I know there are other things I forgot to ask but these were the things off the top of my head.

If this has been discussed here before please point me in the correct direction. A search didn't turn anything up.

Thanks,
Gary

 

[chrsbrbnk]

soldering is usually at or under say 800f brazing ( also silver brazing/soldering) is above that. So if you were doing a smaller object or thinner say like .060 thick brazing can often be done with a MAPP torch like a turbo torch. Silver solder in a good joint can exceed the tensile strength of the parent metal its also useful for making boring bars or weird cutters like with carbide or hss cutters and low carb body silver solder and brazing rod AND FLUX can purchased at most welding suppliers or Mcmaster

 

[GaryK]

So you are saying that soldering is under 800f and brazing is above?
Propane is good for soldering. Silver solder?

MAPP is good for brazing small things?

Can I use MAPP for silver solder? For brazing or soldering?

I think I'm more confused than before.

Gary

 

[Swifty]

I have found that Mapp gas works well for my model silver soldering. Tried to braze up a tubing handle on a plate compactor that I have, using the Mapp gas torch, struggled to get it hot enough, although it eventually worked. Can't justify having an oxy acetylene set, will just have to stick to Mapp.

Paul.

 

[Entropy455]

That’s correct. The melting temperature of the alloy determines the difference between brazing and soldering.

If it melts under 800 degrees F, it’s soldering.

If it melts at 800 or more, it’s brazing.

The heat source is an independent requirement. As long as the filler material melts, the heat source is hot enough. Personally I like to use a very hot oxy-acetylene flame for brazing. Reason - I rarely flow large joints (like you would on a condenser tube sheet), which would require a more broad and less intense heat source. If you are doing fillet type brazed joints, a sharp and hot flame usually provides best results.

Traditional silver alloys are in fact brazing alloys (even though silver brazing is often referred to as silver soldering - I think it’s an over-seas thing. . . .) Silver brazing alloys melt between 1280 and 1600 degrees F, depending on the Cadmium content.

The strength of a brazed/soldered joint is a function of the shear strength of the filler material, together with the shear area of the joint. Consider a typical soldered copper pipe joint. Lead/Tin solder is not super strong stuff, but applied over a large surface area of a socket joint - you’ll blow out the pipe long before you blow out the joint.

 

[chrsbrbnk]

try not to breath the cadmium

 

[Tin Falcon]

Good answers as always I will attempt to add my $0.02 without too much redundancy.

the temperature difference was explained .
another difference is joint preparation . in soldering you need a tight joint for the solder to suck into. there are lot of types of solder.

1) soft solder AKA plumbing solder the old stuff is lead based the new stuff tin based uses acid flux.
2) electronic solder made with rosin core for flux same lead tin base as above.
3) gold solder low temp made of gold silver and a little copper comes in yellow and white colors to match the item being worked on.

3) Silver solder is the mainstay for model engineering as it has the strength needed at higher temperature for boilers.

4) brazing is done with brass alloys . the main difference from above is you can fill gaps and form fillets.
5) the common flux for above is borax /boric acid but can vary some.

Tin

 

[GaryK]

That clears some things up, thanks.

So if I wanted to silver solder to make a boiler for example would I be able to use MAPP?

I would really hate to have to invest in a torch setup and all that is entails.

Gary

 

[GWRdriver]

So if I wanted to silver solder to make a boiler for example would I be able to use MAPP?

Gary,
You might, but that would depend entirely upon the size of the boiler and what style MAPP torch you have in mind. I can tell you that you will be unable to successfully silver solder a typically designed copper boiler of 2" OD or more with the D.I.Y.-type MAPP bench torch. To do that size boiler will require at least a plumber's "turbotorch"-type torch, with a 5/8" diam or larger tip, and tank fuel supply.

You could use such a D.I.Y torch, by supplying the majority of the heat by some other means (charcoal, gas stove, etc) and using the MAPP torch for localized heating, but that would be very dodgy at best.

 

[chipenter]

The main problem is heat loss a brazing hearth is just a lot of fire bricks to reflect the heat back towards the item being worked on, I don't have a hearth but turn my foundry on its side and put the work inside . the size of the item is directly in proportion to the torch being used .

 

[Mawitö]

4) brazing is done with brass alloys . the main difference from above is you can fill gaps and form fillets.

Thanks Tin, i had that doubt myself and you solved it.

I also was wondering about gases, what are your options when you only have access to propane and pure and simple air? can this be enought? or you have make your own HHO generator and pray not to blow up, where i live acetylene or oxygen bottles are completly out of hobbiests reach.

Thanks

 

[Tin Falcon]

you may get enough heat from a turbo torch.
Tin

 

[canadianhorsepower]

Soldering

From Wikipedia, the free encyclopedia

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For the song, see Soldering (song). For the product, see Solder.

Desoldering a contact from a wire.


Soldering is a process in which two or more metal items are joined together by melting and flowing a filler metal (solder) into the joint, the filler metal having a lower melting point than the workpiece. Soldering differs from welding in that soldering does not involve melting the work pieces. In brazing, the filler metal melts at a higher temperature, but the workpiece metal does not melt. Formerly nearly all solders contained lead, but environmental concerns have increasingly dictated use of lead-free alloys for electronics and plumbing purposes.

this is not an opinion but the thruth

 

[robcas631]

Well said!

 

[BronxFigs]

I want to fabricate a black-powder, "pirate-type" cannon. The length of the barrel will be 20 inches, and the largest section of the breech, will be about 5 inches in diameter. For the barrel, I plan to use a thick walled steel tube measuring 18 inches long with an outside diameter of 2.75 inches X 1.250 inches inside diameter (bore dimension). A breech-plug will be welded into the back end of the barrel. The breech section will be approximately 12 inches long. I will bore a blind hole in it, 10 inches deep, and I will basically force the barrel section into the breech section. However, I would also like to add decorative moldings to the breech area and would like to "stack" some larger diameter slices of 6 inch diameter round stock to the breech area. I will be essentially stacking steel "doughnuts"onto the barrel tube. The larger diameter moldings will be turned to profile after everything is stacked, and forced together. My friend has a lathe, and chucks that can easily handle this size work. The "force-fitting" is my problem. Other than using a large press, I will have to beat the barrel into the breech section with a big hammer.

I'm hoping that after all the sections are made, I will be able to assemble the cannon by a using light force fits. I plan on heating the breech section and cooling the barrel by freezing, then quickly sliding the sections together...and praying, a lot. After reaching room temperature, they will be locked together, Assuming that I could accurately bore a straight hole into the breech just slightly smaller, by a few thousandths, than the outside diameter of the barrel, can I silver solder/braze the whole assembly together so that no seams show? I would also like to braze/solder the trunnions into the gun, and form nice, finished looking, fillets. My ultimate goal is for this barrel to look like it was turned from a solid hunk of steel.

Is there any hope of doing this kind of thing in a home shop, or should I take the whole thing, after machining, to a iron works and let them force fit, and braze the whole thing together. I know I have been rather vague but I was just hoping for your best guesses as to my success. Will Home Depot type MAPP gas and burners be able to heat the breech so that it expands big enough for me to slip in the barrel?

Casting, and subsequent boring of this barrel are beyond what I can afford at this point. The scrap yard is my only option, and the little boy in me is calling. Is there a better way to do this kind of job?

Opinions....options....


Frank

 

[napoleonb]

I'm by no means a cannon expert, although I've won several state and country championships with blackpowder rifle's and shotguns so I know a thing or two about blackpowder and gun construction. The first thing you have got to ask yourself is to what purpose do I build this cannon. All legalities aside (depending on country/licenses etc.) if you plan on shooting it your in a total different ballgame as opposed to a showpiece.

Even if you plan on firing it once with a light charge, I wouldn't recommend your fabrication processes from a safety standpoint.

 

[GYoung]

Threading the breach plug and gudgeons into the barrel is one way of assembling your cannon. I have a large model Civil war cannon made to use black power that is manufactured this way. It works quite well.

 

[BronxFigs]

Thank you for the suggestion re: threaded breech plug and gudgeons/trunnions. I came up with this construction plan because:

1. I have no desire to lift and then chuck, a solid hunk of steel, then deep drill a 2" - 2-1/4" diameter hole that's 18" long.

2. Working and lifting shorter, lighter, sections for machining seemed more unlikely to produce the anticipated hernias. I will not be able to lift a 6" diameter X 20" piece of steel without a block, and tackle. Turning a cannon barrel to the desired profile, will take forever, and I will be using a lathe in a friends shop, so I don't want to tie up his machines for too long a time.

3. Cannon will be used to make noise on the 4th of July, and fire blank salutes.

All comments will be taken seriously. The first cannon I made was cast, bored and then steel-sleeved. I always wanted to make just one more. But prices have risen over the last 30 years, so having work done by others is now out of the question. I do it, or, it won't get done.

Frank

 

[Alchymist]

I'm hoping that after all the sections are made, I will be able to assemble the cannon by a using light force fits. I plan on heating the breech section and cooling the barrel by freezing, then quickly sliding the sections together...and praying, a lot. After reaching room temperature, they will be locked together, Assuming that I could accurately bore a straight hole into the breech just slightly smaller, by a few thousandths, than the outside diameter of the barrel, can I silver solder/braze the whole assembly together so that no seams show? I would also like to braze/solder the trunnions into the gun, and form nice, finished looking, fillets. My ultimate goal is for this barrel to look like it was turned from a solid hunk of steel.
Frank

You cannot silver solder a joint such as you describe. Silver solder to be effective must have clearance between the parts to be joined, typically a few thousandths. This is because capillary action is what draws the solder into the joint. So a press or heat shrink fit is out.

 

[BronxFigs]

Alchymist, and others...

Let's assume that the barrel gets made as planned, and all the pieces are now pressed and stacked, like doughnuts on a stick, onto the central tube. Can brazing alloys be used to bind all the sections together? If yes, should I apply heat into the central bore hole, which is 2.250" diameter X 18" long and apply the brazing alloy to the joints so it wicks toward the central bore. I read that these alloys when melted flow towards the hottest areas. The stacked sections will be sufficiently held in place because of the pressed, interference fits, the brazing/silver solder is just for hiding the joints and seams if necessary, and for nice, smooth, fillets.

Frank