welding/soldering

[Bootlegger]

  Mornin Guy's,
  I am making some control horns, and am using 3/32" wire and 1/4" metal for the horn's
 Will Mapp gas melt and flow brass brazing rods?
  Also what is the content of silver in silver solder, and what content is best used for these horns?
   Thanks a lot...

[John Cralley]

Real jeweler's silver solder comes in three basic forms (hard, medium and easy - also maybe super easy) and requires an oxy/acetylene or natural gas/oxy torch to melt. The stuff that you can buy at the hardware store has little silver in it and, though stronger than regular solder, it is no match for real silver solder and it will melt with a soldering iron.

[Tim Wescott]

If I recall correctly MAPP gas has a temperature between propane and oxy-acetylene, and won't melt brass brazing rod (you need to get the metal up to a fairly bright red heat to melt brass).  You can try, though.  Heat up some scrap music wire or a nail with your torch: if it doesn't get so bright that you can't look at it comfortably, it isn't suitable for brazing (you need welding goggles to braze with brass).

I don't know what silver solder alloy in specific would work with MAPP gas, but even a propane torch gets you up to a significantly higher temperature than a soldering iron, so there ought to be some choice that'll get you way more strength than just solder, and still work.  Google really should be your friend, here.

[Dan McEntee]

  I spent my last two years of high school in a fitter/welder program at a local tech/high school. If I remember correctly, soldering processes take place at temps up to 400 degrees F. Brazing processes take place at temps up to 800 degrees F., and anything over that requires a welding/fusion type process because soldering and brazing alloys oxidize and burn above that temperature. Silver soldering fits in the area of high soldering temps and low brazing temps.  For our uses in stunt, especially for control horns, a low temp silver soldering will be more than strong enough if done properly. I use the Stay Bright products available at the hobby shop with great confidence and success. it's low silver content, but pretty high strength and reasonable in cost. The big thing with soldering, silver soldering and brazing is GETTING THINGS CLEAN!!! When you think you have it clean, clean it again. Next is using the proper flux, and then getting things to the proper temperature. When all is correct, the soldering/brazing material should flow smoothly. If you have to really work at getting the material to "take", you have something wrong. Joints should also be as tight as possible. Soldering and brazing material works like thin CA glue and takes advantage of capillary action to flow between the parts, and large gaps won't work or fill. If everything is right, it will look right, smooth flow, shiny, no lumps or bumps. The best thing to do to achieve these results consistently is PRACTICE, PRACTICE, PRACTICE!!!!  If the equipment you have is not getting the job done, then don't force the issue and get the correct equipment if you want to keep doing the job yourself. I haven't tried it, but MAPP gas should get hot enough for 1/8" horns and steel arms, but then so should a 40 to 60 watt soldering iron for Stay Bright. The parent material doesn't have to get red for it to flow, and it it does, you stand the chance of oxidizing the joint and risk failure.
   Good luck and have fun.
  Merry Christmas and Happy New Year,
   Dan McEntee

[Perry Rose]

Silver solder should have the percentage of each metal on the label. Look for SN and PB with a number following each. Like SN60 PB40. Pb is Latin for lead and is on the periodic table. It's pronounced plumbum, I don't know how it's really spelled.
  I use a propane torch and I have to heat the parts red hot before the braze wire melts. No failures to date.

[Bill Little]

Hi Gil,

I get my silver BRAZING wire (on a spool) along with the proper flux at a local welder supply.  I have a small butane torch which gets it hot enough to do the job.

BIG Bear
AMM/RNMM

[Tim Wescott]

It sounds like Dan knows a lot more about this than me.  All I can add to what he said is -- yup.  You can never get a solder (or a braze) joint too clean.  All traces of grease, corrosion, etc., need to be cleaned off or things just won't work.  If you've got things absolutely clean and your joint still isn't happening, then you need to change fluxes (or you're trying to solder the wrong thing to the wrong thing).

It would be interesting if someone would try a bunch of different processes and solders (or brazes) to find which ones work well.  I'd like to see someone make up a bunch of horns and test them to destruction.  For me, I'd want to see the wire bend before the solder joint fails, and I'd like to know how much allowance can be made for poor joints (i.e., at what point do I reject a part because it fits too loose).

I happen to use brass to braze on my control horns -- not because I think it's the ultimate stuff to use, but because I don't happen to have any silver solder (or braze) in the shop, I don't think that 50/50 plumber's solder will be adequate, and I am set up for brazing.  I should try Stay Bright.

[Gary Anderson]

Hi guys,
I agree with Dan, remember when ya get things red hot ya take away the strength. Use a good soldering gun for the items we make and follow what Dan stated and it will work great for ya.
Gary

[Dallas Hanna]

 Mornin Guy's,
  I am making some control horns, and am using 3/32" wire and 1/4" metal for the horn's
 Will Mapp gas melt and flow brass brazing rods?
  Also what is the content of silver in silver solder, and what content is best used for these horns?
   Thanks a lot...

Quite a bit has been written on different forums about this process.  Stunt hangar and SSW.  Do a search on "silver brazing" or "silver soldering" and see what comes up.   This is one:

http://www.clstunt.com/htdocs/dc/dcboard.php?az=show_topic&forum=103&topic_id=331672&mesg_id=331672&listing_type=search

http://stunthanger.com/smf/index.php?topic=13861.msg125743#msg125743



HH

[Brett Buck]

For our uses in stunt, especially for control horns, a low temp silver soldering will be more than strong enough if done properly. I use the Stay Bright products available at the hobby shop with great confidence and success. it's low silver content, but pretty high strength and reasonable in cost.

    I hate to be a naysayer because there was so much good information in the OP, but Sta-Brite IS NOT sufficient to hold the upright on a plain wire control horn without some additional modifications to reduce the load on the joint. At least not with the uncontrolled conditions that modelers are going to have. It will hold for a while but, like R/C clevises, it's just a matter of time before it lets go. It's the ultimate nightmare to fix, assuming you get out of it intact, basically have to cut the entire airplane to pieces to replace the flap horn.

     It you are going to use Sta-Brite, you need to make a different type of connection that reduces the demands on the ultimate strength of the solder.  I recommend Keith Trostle's "key" method, where the 1/8 wire is backed up with a 3/32 wire "key". Done correctly you have to drive the "key" into position so that the upright is essentially rigidly held in place even before you solder it. Wrap and solder, and you *might* be OK if you do the soldering EXACTLY right.
    
    And alternative is the Russian (Belko and others) method of bending the upright from the wire itself. Instead of a single piece of wire, make it in two, and bend the upright right into the material. Then wrap and solder the two halves together. You end up with a wire end that fits nicely inside a ball link ball, and it greatly reduces the loads on the upright solder joint.

    I use and recommend a very small brazing wire I get at the local hardware store myself. It is more than adequate for a plain flat upright on a wire horn. It can be heated sufficiently with a propane torch if you are willing to wait long enough, but I use MAPP gas which seems a lot more capable.

    And I suppose everybody already knows this from Ron Burn and Derek Moran's treatises on the topic, but don't use music wire, use drill rod. It can be heated high enough to melt bronze or silver braze without having to harden and then re-temper the metal or worry about cracking from hard spots later.

    Brett
    

[GGeezer]

Brett,
Is Drill Rod not O1 tool steel? If so, it only has a hardness of approx. Rockwell B 100 when purchased. This is soft when compared to the springiness and hardness of piano wire for the same wire diameter. Do you subsequently heat treat the drill rod after welding and how do you do this since the hardening temp. would melt the brazed joint?

Orv.

[Brett Buck]

Brett,
Is Drill Rod not O1 tool steel? If so, it only has a hardness of approx. Rockwell B 100 when purchased. This is soft when compared to the springiness and hardness of piano wire for the same wire diameter. Do you subsequently heat treat the drill rod after welding and how do you do this since the hardening temp. would melt the brazed joint?

   It's pretty soft compared to music wire. I can only refer you to the previous posts (one of which is noted above) on the reasoning.

   Brett

[Dallas Hanna]

Some time ago similar questions were asked on the Barton, UK forum . Whilst making some new horns for the latest woftam, I made a sacrificial horn to do some testing. The up to 51 size model with 3/32" K&S are fine and have never failed.    The R&B 75 beast has 1/8" K&S for all horns.

The test horn was made from 1/16" gauge plate with 3/32" K & S wire.  Silver brazing rod is 1/16" dia. 40% (approx) silver.   Yes I do use oxy acet but the butane torch will do it fine at these sections.   Now for the sacrificial lamb! Good grief, the bloody thing did break!! I purposely silver brazed the horn on 45 deg out of position. I then twisted it back to 90 deg. No problem here yet BUT after 55 twists back and forth through 90 degrees the darn thing broke.     You will also take note of the remaining portion being bent 90 deg to the axis and it didn't break.

If others aren't convinced, do the test yourself and note the results.

HH

[Andrew Tinsley]

Perry,
Silver solder is NOT a tin /lead alloy as you said. That stuff is conventional soft solder! Guaranteed to fail in any horn soldering! Silver solder is an alloy of silver with cadmium, copper, tin and zinc. There are also types with no cadmium. The Silver content varies from roughly 50% downwards. Those alloys with the highest silver content have the lowest melting temperatures. Some alloy specs are gap filling, capillary action, or even produce good fillets. ALWAYS choose the type of silver solder appropriate to your need. It is NOT a case of one fits all!
  A correctly executed silver solder joint with the correct solder is more than strong enough for our needs. But note that Dan is correct in saying the joint must be correctly made otherwise all bets are off! Read and reread what he says about cleanliness and fluxes. I am lucky in having oxyacetylene kit and a whole range of silver solders!
  Mind you a correctly made brass "braze" is just as good for our uses, but I find it more difficult to execute than a joint using silver solder. I use silver solders in model loco boiler construction. I have never had a joint fail be it in a loco or an aircraft. Use the right flux and silver solder (or braze) do as Dan says and you will never have a horn fail!

Regards,

Andrew.

[Tim Wescott]

Perry,
Silver solder is NOT a tin /lead alloy as you said.

Silver solder should have the percentage of each metal on the label. Look for SN and PB with a number following each. Like SN60 PB40.

Man, I completely missed that the first time around!!  Sn is the chemical abbreviation for Tin -- Ag is the chemical abbreviation for silver.  Pb/Sn solder is regular old lead/tin soft solder!

There are "silver-bearing solders" out there, with low percentages of silver, but I have no idea how strong they are.  There are also lead-free electronics solders that have quite a bit of silver in them and which are not designed for high strength -- they're designed to mimic the soldering properties of regular old lead-tin solder.  While they're harder than lead-tin solders I doubt they're even remotely up to the strength of "real" silver solder that's intended for structural use.

[Bootlegger]

  First off Guy's I sure do thank you for the info. Today I did some research and found out the the solder/flux was 45% solder and 55% iron in with the flux.
  J H Harris company made this solder, but they have discontinued it.  I had made some horns using it and they did not break, so I am in persuit of a simular solder/flux combo.
  It was sold in a syringe containing 1 troy oz of this combo, if anyone comes up on a simular set up please let me know where I can get it, in the mean time I am going to braze the jounts.
  Again thanks for all the info.....

[John Leidle]

 I dont remember Kieth's key method . My horns seem ok but I sometimes worry a little. Any diagrams of such or the Soviet type would interest me.
  john

[Bob Reeves]

Pulled this from the plans I drew for my FJ-4B carrier airplane, this works well using plain old 60-40 electronic solder.