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Silver soldering

Old 01-28-2007, 09:32 PM
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trickydevil
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Default Silver soldering

I need to do some silver soldering. I have the silver solder, now I need some flux. Is brazing flux the correct stuff to get? Also, will a propane torch be hot enough? Its only for doing small areas, (if this makes a difference).

TIA

Richard
Old 01-28-2007, 09:50 PM
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alan0899
 
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Default RE: Silver soldering

G'day Mate,
Borax is generally used for silver soldering, it is mixed with water, & is a soft paste, available in plumbing supply stores or hardware stores, under silver brazing flux.
You propane torch should be hot enough, for small jobs, just heat the end of the rod, if it melts, your torch is hot enough.
Old 01-28-2007, 10:02 PM
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bofrcr
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Default RE: Silver soldering

hey there! well,,first,, what EXACTLY,, are ya joining? is the "silver solder" you have a stiff kinda wire? If it is,, you'll need an oxagen/acetylene torch to produce enough heat (get it RED HOT) Have you ever heard of stay-bright? It's a silver BEARING type of sodler,,about half-way between regular solder,and braze,, as far as strengh goes,, it's worth having in the shop,, as you can use a soldering gun with it,, if you've got a welding supply store in your area,,(no,,not the "big box" kinda store!),, go and as them,, they'll steer ya in the right direction, braze fluz WILL work,, but siver solder's is different. My 2 cents worth?,,, go talk to the experts.
Old 01-28-2007, 10:05 PM
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bofrcr
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Default RE: Silver soldering

hey!,,LOL Alan is right,, I forgot about borax!!
Old 01-28-2007, 10:13 PM
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Charlie P.
 
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Default RE: Silver soldering

I have a Weller 260/200Watt soldering gun I use for my silver soldering. Brazing is a higher temperature affair than soldering, but I think flux is flux. It is an acid that allows the solder to bond better. It comes in paste or liquid. I use the liquid, but it is sold as "soldering flux"

Be sure to clear it off afterwards. I buff my joins up with a stainless brush or the wire wheel from my Dremel.

A friend charred the cockpit of his Tiger Moth using a torch to solder the cabanes. Be sure you protect the wood for the first foot or more of the torches' path.
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Old 01-28-2007, 10:42 PM
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trickydevil
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Default RE: Silver soldering

Thanks for the replies, advice taken.

Richard
Old 01-30-2007, 07:00 PM
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Woodpile
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Default RE: Silver soldering

Just want to clear up a few misconceptions here.

1. You cannot silver solder with an electric soldering iron. Any true silver solder has a melting point between 800F and just over 1200F (which is for pure silver). I don't know of any electirc iron that will reach those temps.

2. Flux ain't always flux. Acid based fluxes, usually Zinc or Ammonium Chloride, will burn long before you can melt silver solder and the parts will never bond. It's good for lead/tin solders (for those of you who remember the good old days of 50/50 or even 60/40) and it will also work with most lead-free plumbing solders commonly on the market. Borax is used in silver soldering, no to get the solder to stick, but to prevent oxides from forming on the base metals. Same as the coating on stick-arc welding rods (SMAW) or flux core welding electrode (FCAW).

3. What most people here call "silver soldering" is "soft soldering" like what a plumber does or used it electrical connections. I've even seen kit construction manuals call it "Silver soldering".

4. You can silver sodler with a propane torch, as long as the pieces are relatively small and you have a big enough tip. Usually, you'll have to get the base metal red hot. If your torch will do that, the silver sodler should melt.

5. If you are soft soldering and use an acid flux, make sure you clean it VERY well. It will corrode the base metal something fierce. It will also absolutely destroy any wood it soaks into.

6. Silver soldering is NOT reccomended for landing gear wires as you'll ruin the temper and have no way to put it back in. In fact, I would be hard-pressed to think of any application for silver soldering in this hobby, with the possibilty of custom made gasoline mufflers

Not trying to pick on anyone, just trying to get accurate information out.

Ed
Old 01-30-2007, 10:39 PM
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trickydevil
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Default RE: Silver soldering

I was considering silver soldering (not soft soldering) a brass control horn to a wire torque rod (elevator joiner). I was under the impression that soft soldering is not intended for "mechanical use" and therefore not strong enough, hence the need to use silver solder.
I did wonder about the heated areas becoming hard and brittle but have read many times about silver soldering being used to do similar things. It is something that i need to look into 'cos I would like to fabricate my own parts instead of using plastic "hobby shop" parts and I need the joints to be strong and reliable so they are "fit and forget" so to speak. Espicially if the joint is hidden inside a fusalage for example. So what do I do?? Would the heating process make the metal too brittle or has anyone used it successfully?

Any alternative ideas would be welcome.

Richard
Old 01-30-2007, 10:57 PM
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Default RE: Silver soldering

I have used "Stay-Brite" (soft solder ) on brass control horns with no problems. I am doing this on scale models, not "hot rods" though, so the forces on the solder joint are not as great.
Old 01-30-2007, 11:00 PM
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trickydevil
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Default RE: Silver soldering

OK, thanks, "stay bright" has been mentioned a few times, I will get some and give it a go.

Richard.
Old 01-30-2007, 11:24 PM
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Charlie P.
 
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Default RE: Silver soldering

1. You cannot silver solder with an electric soldering iron. Any true silver solder has a melting point between 800F and just over 1200F (which is for pure silver). I don't know of any electirc iron that will reach those temps.
Huh? Then what have I been doing with 2 to 3% silver solder that I have been lead to believe is silver solder, sold as "silver solder", and holds up like silver solder? At what point does the tip of a Weller glow red? If I leave mine on it does in a few seconds. I believe you're thinking 25W soldering pencils and not heavy duty 200 to 300 W soldering guns. http://www.testequipmentdepot.com/we...rgunselect.htm According to the manual of my Weller D550 the tip reaches 1,100ΒΊ in six seconds at the 260W setting, 900ΒΊ at the lower 200W setting.

If it looks like a duck, smells like a duck and "quack's" like a duck . . .

If you're introducing a metal rod into a join I thought it was welding or brazing. Soldering fell under electrical vs. silver (conductive vs. fastening). Live and learn.
Old 03-11-2007, 11:18 PM
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Arkitexas
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Default RE: Silver soldering

The term SOLDERING applies when a bonding metal or alloy (lead solder) is used with a melting temperature less than 450 degrees to join one base metal to another. The bonding metal melts and flows by capillary action and adheres to the base metal. The base metal itself never melts. This usually involves alloys such as lead solder which are a 60/40 mixture of tin and lead. Lead solder melts at about 360 to 400 degrees depending upon the % mixture. There are also solders which contain metals other than lead but they are slightly harder to work. The term silver solder is a very common misnomer and is actually silver brazing.

The term BRAZING applies to the same action as soldering but the melting temperature is between 450 and 1200 degrees. This process involves bonding base metals (without melting them) using alloys with a higher melting point such as brass and silver. Thus connections can be made which are stronger than soldering and can withstand higher temperatures as well as more vibration.

The term WELDING applies when the two base metals are actually melted together in the attachment process. Usually a filler material (welding rod) is added to full the void between the two materials. The filler material may match the base materials or be a different, but compatable, metal or alloy.

There are other high-bred processes that often blur the lines between these terms. Likewise, local colloquialisms cross boundries.

You can silver braze using a big soldering gun, it just takes longer to get the base metal up to temperature. Usually a torch of some sort is used, but in the end, any heat source will work if it can introduce enough heat. The problem with brazing piano wire, such as is used on landing gear, is that the temper of the wire will be altered if it is heated to 900 or 1000 degrees. An alternate solution is to wrap the joint with 5 to 10 turns of finer wire and solder it with the joint. The finer wire must be solderable and clean. The solder will hold everything in place and make a relatively smooth surface (you can still see the wire wrap) and you gain the tensile strength of the fine wire.

The most common problems newbies have with soldering are preparation and technique. The following are steps that need close attention:

1) Prepare the metal surfaces to be soldered properly. This means cleaning the metal of debris and oxidations using a wire brush or file. Flux can be used if residues are removed. Flux is a paste or liquid that etches away surface impuities to aid in good bonding and is usually some form of acid. Do not use acid core solder in any electronics applications. Acid flux can be very caustic and the residues remaining after the soldering process should be removed. Rosin core solder, used in electronics, includes a rosin flux in the core of the solder. This rosin flux is less caustic than acid fluxes and can be left without cleanup. If you do a really good job of brushing or filing the surfaces, rosin core solder will work fine without added flux.

2) Hold the wires in place with clamps or other mechanical means. A large connection will get too hot to hold steady during the heating process. Small wires can be held with your fingers while soldering but it still requires three hands. Harbor freight sells a small cast iron stand with two alligator clip arms. It works great and costs less than $5. I use mine all on almost all my solder joints.

3) Use the proper size soldering iron or gun. The larger the wires or connection, the more heat needed. It is difficult to solder 14 gauge wire to a Deans connector using a 15 watt pencil iron. Even though the iron can reach to 500 or 600 degrees, it can't deliver heat as fast as it is being dissipated. Likewise don't use a 150 watt gun on a printed circuit board.

4) Apply heat to the base metals, not to the solder. This is probably the most common error made by amateurs. The solder will not stick if the base metal is not hot enough. The solder must "flow" between the two metal surfaces. To achieve this bond place the soldering iron's flat chiselled surface in full contact with one of the metal surfaces. This provides the fastest transfer of heat. The solder is then touched to that same metal at another nearby location such that the solder NEVER touches the iron tip even after it melts. In other words, place the iron on one side of the wire and apply the solder to the other side. As soon as the base metal is hot enough to melt the solder, is is also at the correct temperature for a proper bond. The solder will melt and flow through the joint in one quick process. The resulting joint will look good and be strong. DON'T touch the solder to the tip of the iron to speed up the melting process!

5) Keep the tip of the iron or gun clean which will allow it to transfer heat more quickly. When the tip has become tarnished or pitted, file it back to shape until you see copper. Tips on most larger irons have a flat spot while smaller irons usually have a bevelled cone tip. Once shiney, heat it and apply a small coat of solder. This is called tinning. The coating will prevent oxidation of the tip surface as well as improve heat conductivity to the joint.

It is ideal to apply heat for as short a time as possible. To make quicker connections, "tin" the end of the surfaces before making the connection. This involves applying a very small amount of solder to each surface before the actual connection is set up in item 2 above. Once tinned, very little additional solder is needed on the connection and heat is transfered through the joint is much faster.

Happy soldering/brazing/welding
Rick
Old 03-12-2007, 11:33 AM
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jaka
 
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Default RE: Silver soldering

Hi!
Agree!
Stay Brite "silver solder" lead/tin solder is actually a low temp soft solder which is soldered with a soldering iron like a Weller. Real silver soldering is the same as brazing and you need a propane torch or acetylen welding equippement!


For Model flying soldering low temp tin /lead is only what's needed. Not even Say Brite "silver solder" is necessary.
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Old 10-02-2007, 10:05 AM
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Default RE: Silver soldering


ORIGINAL: Charlie P.

I have a Weller 260/200Watt soldering gun I use for my silver soldering. Brazing is a higher temperature affair than soldering, but I think flux is flux. It is an acid that allows the solder to bond better. It comes in paste or liquid. I use the liquid, but it is sold as "soldering flux"

Be sure to clear it off afterwards. I buff my joins up with a stainless brush or the wire wheel from my Dremel.

A friend charred the cockpit of his Tiger Moth using a torch to solder the cabanes. Be sure you protect the wood for the first foot or more of the torches' path.

What type of wire did you use to wrap the Cabanes and who sells it.

Thanks...

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