Control Horn Solder

[Motorman]

Is there a low temp brazing rod that's good for control horns, doesn't cost allot and works with a propane torch. Silver seems very expensive.

Thanks,
MM

[Dave_Trible]

I'd suggest no soldering at all.  It's not strong enough and silver solder flux is very corrosive . Instead they should be brazed.  Use regular hardware store brass brazing rod with flux coating but you have to use MAP gas to get hot enough.  Propane isn't close.  The metal needs to heated to near white hot then the rod applied.  It should flow out in a rapid splay- then just get off it.  These will be indestructable.

Dave

[Tim Wescott]

I'd suggest no soldering at all.  It's not strong enough and silver solder flux is very corrosive . Instead they should be brazed.  Use regular hardware store brass brazing rod with flux coating but you have to use MAP gas to get hot enough.  Propane isn't close.  The metal needs to heated to near white hot then the rod applied.  It should flow out in a rapid splay- then just get off it.  These will be indestructable.

Dave

Or use oxy acetylene. I've seen this discussion before, and there's folks who swear by silver solder. I've been brazing, but I'll be trying silver solder on the next one. Time will tell if it's a smart idea.

Sent from my SM-G900V using Tapatalk

[Target]

MM-

Thinking outside the box, you could NOT RELY on a solder joint at all, and use 2 pieces of bent wires, with 2 90* bends in each.
The two inner downward bends can touch, and a third piece of music wire, or even 4-40 threaded stud can be bounded to other two wires in a triangular vertical fitment (bind with kevlar threads and epoxy, or bind with copper wire and solder if you like).
On the added third piece of wire or threaded stud, slip on an appropriate hole sized ball link ball. If a threaded stud, a nut above and below the ball adds infinite horn adjustment.
The ball link yoke would be oriented in a horizontal plane in this arrangement from the push rod.

The only hang up is that I doubt that you could get much more than 75-80* total throw for the elevator, but I would think it would be enough.
The nice thing about this arrangement is that it doesn't rely on the solder joint integrity to move the elevator.

I hope that you can understand my description. I have a picture of what I am talking about somewhere, but hard to find it right now.

Regards,
Chris

[JIM Nordin]

I been useing stay brite silver solder . I have stuff that 20 years old with no issues . It's a lot stronger than your normal solder you use for copper pipe ! I have used on high stress joints . On my ducted fan jets

You can use a normal propane .  You can get it from tower and most good hobby shops

[peabody]

Windy built, literally, THOUSANDS of horns, and used silver soldier and mapp gas.......never heard of a failure....

[Brett Buck]

I been useing stay brite silver solder . I have stuff that 20 years old with no issues . It's a lot stronger than your normal solder you use for copper pipe ! I have used on high stress joints . On my ducted fan jets

You can use a normal propane .  You can get it from tower and most good hobby shops

   STA-Brite IS NOT STRONG ENOUGH for control horn uprights on CL planes!!!  Unless you do something to unload the joint, like Keith Trostle's "key" method. It will work for a while, then break loose. Nothing you can melt with a soldering iron will make it.

    I use silver braze The diameter is critical. I make up a pre-formed ring of the .030 diameter 56% silver brazing material so it fits around the wire, use flux on both sides, then slip the ring over the wire and down to the horn. I use a MAPP gas torch and in about 15 seconds, it melts, and makes a perfect fillet on both sides.

    Brett

[JIM Nordin]

LOL if you say so . Never knew I was doing wrong

[Chris Brainard]

I silver braze mine with Eutectic Silver-Weld...the same stuff I braze my bandsaw blades together with. This makes a stronger joint than a welded joint on a bandsaw blade, which is subject to impact, vibration, constant flexing and pressure. Mapp gas in a propane torch works great. When I tested the strength of the joint on a control horn, it destroyed the horn but the joint wouldn't break.

[Brett Buck]

LOL if you say so . Never knew I was doing wrong

   I have seen many STA-Brite jobs fail, and when it does, you frequently have to cut the entire airplane to pieces to get to it.

    Brett

[Motorman]

Does anybody make square music wire?

I'd like to use silver but I thought bronze would be a cheap alternative. What's stronger silver or bronze?

Back in the day dad got this real low temp brazing rod from Sears. Would love to find some of that again.


MM

[Derek Moran]

Here is some relevant information including material sources and part numbers.

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

Derek

[JIM Nordin]

Brett I just think it funny  that someone tells me something won't work when I been doing it for decades .i retired after 47 years as a maintenance welder tinsmith . For a major oil company . At a large west coast refinery

If my joint fails in a refinery its a lot worse than a balsa pile on the ground . If a solder joint fails it's because it wast propery done .  I trust my stay brite silver solder joint planes have not had one fail in 30 years . RC and UC
Then against it might be skill !

[frank williams]

I use this braze for horns.  Takes a torch to melt.
http://hardwaredistributors.com/braze-wire-and-flx-silver.html?gclid=CISB16ndjsoCFc5gfgodA_ENQw

[Brett Buck]

Brett I just think it funny  that someone tells me something won't work when I been doing it for decades .i retired after 47 years as a maintenance welder tinsmith . For a major oil company . At a large west coast refinery

If my joint fails in a refinery its a lot worse than a balsa pile on the ground . If a solder joint fails it's because it wast propery done .  I trust my stay brite silver solder joint planes have not had one fail in 30 years . RC and UC
Then against it might be skill !

       OK, do as you want, but I will not recommend it myself, having seen the results.

     Brett
     

[Clint Ormosen]

Brett I just think it funny  that someone tells me something won't work when I been doing it for decades .i retired after 47 years as a maintenance welder tinsmith . For a major oil company . At a large west coast refinery

If my joint fails in a refinery its a lot worse than a balsa pile on the ground . If a solder joint fails it's because it wast propery done .  I trust my stay brite silver solder joint planes have not had one fail in 30 years . RC and UC
Then against it might be skill !

Jim, I don't doubt your skills. I used the same method as you for years, and like you, I never had a failure.

Until I did.

My Sta-Brite joints seemed so solid. I scoffed at the idea one could ever come loose. But one day out sport flying with a Goldberg Buster, my custom built horn just came apart at the joint. A clean break. Upon inspection, it's obvious the soldered joint just didn't have any penetration into the wire and after enough flights the vibration broke it loose. I got lucky and the model belly landed instead of becoming a lawn dart. Also, I have a few other models with more flights on them that still have Sta-Brite joints in them. I just keep my fingers crossed on those.
Now I braze my horns (if I have to make one) with a torch and 15% silver.

[Dan McEntee]

    Any kind of solder or braze joint will fail if not done correctly. Proper training, equipment and skill do have a lot to do with it. I'm a trained welder and fabricator with 40 some odd years experience and have taught the subject. Proper heat is really important. You can have a cold joint, which I have seen a lot of pictures of here on the forums, and you can over heat the joint also. Over heating the joint causes oxidation and burns the silver out of the compound. Using the good, high content stuff is great if you can afford it and have the equipment and skill to do the job correctly. It's not something you get nailed in one or two tries if you have no experience with a torch. I have used Stay-Brite on countless projects both in modeling and in industry with good results. It is lower temp than the high content stuff, but higher than needed for lead/tin solder. For doing 3/32" or 1/8" control horns a soldering iron won't get hot enough. It might flow some what but will be a cold joint. If you use a torch, you need to keep the torch moving to avoid over heating and oxidizing. Things have to be CLEAN, and no gaps in the joint. Any kind of re-enforcement at the joint always helps. The more surface contact, the better. It's one of those things I can show you better than tell you. Practice and experience tell you when things are right. If I didn't do this kind of stuff for a living, I would just use Tom Morris' stuff and be happy, or make friends with some one who knows how to do it.
   Type at you later,
   Dan McEntee

[GregArdill]

Well said Dan

It seems that there are in fact many ways to skin this particular cat.

But I wonder what is the real cause of control failure.

Is it a bad joint using what ever method you prefer, or is it that too much stress is put on joints by poorly aligned moving surfaces?
If your surfaces are working against each other then I doubt that any horn will survive in the long run.
Think also that pushrods that foul & rub are going to cause a lot of problems as well.

[peabody]

I emailed Windy....he used a silver braze that he got from Russ Hunsberger... he used a flux and map gas...
he neutralized the flux with a baking powder mix....

[Dan McEntee]

Does anybody make square music wire?

I'd like to use silver but I thought bronze would be a cheap alternative. What's stronger silver or bronze?

Back in the day dad got this real low temp brazing rod from Sears. Would love to find some of that again.


MM

   
    This is where a lot of confusion starts. There is soldering, brazing, and welding (fusing the parent materials together.) I can't remember exact temps and too lazy to get out a book, but it goes something like this. Soldering processes take place in the 400 degree range, brazing in the 800 to 900 degree range, and welding 1200 degrees and up. I'm sure I'm missing the mark on these but that is approximate. Been a long time since welding school!
   Temperatures can vary with the size of the pieces being joined. And temperature is relative to the amount of heat applied to achieve the results needed. The size of the pieces need teh proper amount of heat to achieve the temps you need to get acceptable results. If you solder a horn to a 1/8" music wire with lead/tin solder, you will either have it too cold for the solder to flow correctly and make a cold joint, and if you get the pieces hot enough, you have so little soldering material there that it will oxidize and burn at the temps the pieces are at, because of the quantity of heat. If you move up to brazing processes, you have to be careful of what size filler material you use, and the size of your heat source. Again, if you don't get the pieces hot enough, the filler material won't flow completely and just lay on the surface. You can have a cold joint that looks normal. If you get too hot, the filler material oxidizes and burns, making it brittle. If you don't know what to look for at the time you will think all is OK until the joint is stressed. The high content silver brazing rod is most certainly stronger, but needs to be applied correctly and in proportion to the pieces you are working on. The term (low temp brazing rod) is kind of an oxymoron. You can't braze effectively until you get to the specific temps required. Stay-Brite is probably as close to this description as you could get I think. You can apply it with a hot soldering iron on pieces or wire up to a certain size. A 30 watt iron at 400 degree is way different that a 100 watt soldering iron at 400 degrees. Same way for a torch, no matter what kind you use. If it takes you a long time to get the pieces hot enough to flow, your heat source isn't big enough. And if the joint pops, crackles and sizzles, it's too big. Heat source needs to be sized for the job along with the filler material.
    And bronze isn't a filler material, brass is. Bronze is an alloy of copper and zinc (I'm pretty sure) and brass is an alloy of copper and tin. That is what gives it the ability to to flow and bond itself to the parent materials at the proper temperatures.  Again I don't have a book in front of me to double check but I believe I'm close.
     Sometimes looking for a cheap alternative on a critical part can cost more than you think.
    Type at you later,
      Dan McEntee

[Brett Buck]

If anyone insists on using soft solder like Sta-Brite or 60/40, at least do as Bob Reeves shows in this thread:

http://stunthanger.com/smf/open-forum/weldingsoldering/msg236566/#msg236566

   This is "key" method I learned from Keith Trostle. This reduces the loads on the solder joint. The key needs to fit tightly, almost to the point you have to drive it in. Then solder the upright and key to the cross-bar, clean it perfectly and remove any excess solder, then close-wrap with moderately heavy uncoated copper wire, then solder on that and allow it to flow under the wire and fill the space completely. If you leave any gaps, it is very likely to trap some flux and will eventually corrode the wire or the upright.

    As Jim notes, technique is critical and the solder has to flow perfectly and make perfect fillets everywhere. Then clean it with water, then backing soda and water, then polish everything with a small wire brush. Inspect, if you see any black spots or gaps, try again. You probably have to use a propane torch unless you have a big old industrial soldering iron like an American Beauty, but you don't need or want to get anything red hot, just hot enough to flow out the solder like water. A little too hot, and the steel will oxidize and it will all ball up.

     I have never seen a failure of this when properly fitted up even using pretty weak solder like Sta-Brite. It's a bit heavier and more prone to failures of technique, but it's good enough. You don't want to count on soft solder to hold a simple upright on the wire, it will not stand up to the pounding taken on a competition stunt plane. It's just like RC clevises, no matter how tough it seems, it will fail.

   Finally, this is the correct way to construct a control horn:

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

     Derek uses 45% silver solder which flows out easily. I use 56% but the results appear the same. It's nearly magical the way it forms perfect fillets when done this way, and that it easily flows through to the other side and makes a nice fillet there, too. You can use the "key" method, too, but it's not necessary.

    Brett

[frank mccune]

     Hi All:

     From what the little I think about soldering, brazing and welding I think that brass is an alloy of copper and zinc and bronze is an alloy of copper and tin.  I may have this backwards so take it with a grain of salt.  Old Age is great! Lol

     Soldering takes place at less than 800 degrees F and brazing talks place at temperatures in excess of 800 degrees F.  Joints must be:

Tight

Clean

Heated to the PROPER temperature

If one of these requirements are not provided, failure is eminent!

     Remington Arms used silver brazing on some of their firearms.  The locking lugs were silver brazed onto the bolt in their bolt action rifles for many years and it work well!  An additional piece was machined with integral  locking lugs and it was this piece that was silver brazed onto the bolt body.  A great way to make a bolt circa 1950 to present. I think they used Shelby seamless tubing.  This was much less costly than forging and machining a bolt!

     The bolt handles were also silver brazed to the bolt.  I broke a bolt handle off a  Remington 722 when I dropped the bolt onto a concrete floor.  I reattached the handle with a bit of silver braze and all has been well.  Why it broke? Perhaps it was just a perfect storm for failure.

     Dan has written a great post regarding silver brazing!

                                                                                                                        All of the best for 16,

                                                                                                                        Frank McCune

[John Leidle]

   Thanks to all you responded here I do mine somewhat as Bob Reeves posted but his look superior. I am in the process of making mine & will consider his method.
                     John

[Lyle Spiegel]

I'm a metallurgist and welding/ brazing engineer, spent my entire career in high tech aerospace, and would like to add my 2 cents to the discussion about silver soldering. Some of you may already know about the info I'm posting.
To clear up any mis understanding re:difference between soldering and brazing.  They are very similar joining techniques, both involve the melting of a filler metal to join two or more components without melting the base material.  Brazing is process which uses a filler metal which has a melting above 842°F.  Soldering uses filler metals which melt below 842F.
Silver-based alloys (those with silver as the primary element) all melt well above 842F and are therefore clearly brazing filler metals. Common silver based brazing alloys can have silver in range of 38% to 45% silver and melt above 1100F. Would not suggest such alloys for use on music wire since the higher temp required can induce brittleness unless heating can be controlled to avoid overheating music wire.
  The  term  “silver solder”  confuses people and this is a misnomer, because the main alloy element is Tin, not Silver. Staybrite you order from hobby shop is 96% Tin, 4% Silver, and has melting point of 430F. Another version of Staybrite has 6% silver, and the melting point is increased to 535F. Can't get to these temps using soldering iron intended for lower melting lead / tin solders so need to heat with a flame .
Melting of  typical 40%lead- 60% tin  solder occurs between 361F- 374F.
Fluxes for soldering are specific to the type of solder being used. Don't use flux intended for lead- tin for staybrite.
Don't use silver brazing flux with stay brite.
Flux residue for silver solders typically can be acidic, thus need to neutralize with caustic (baking soda) compound.

[frank mccune]

      Hi Lyle:

     Great post!  Good to get in formation from a person who knows his field.

     I was taught this information when JFK was president! However, due to the ravishes of time, I could not recall all of the information. Lol

                                                                                                           Have a great 16,

                                                                                                           Frank McCune

[Andrew Tinsley]

Hello Lyle,
Spot on summary. I have used silver solder for 50 years. I used to bind any joints with iron wire, but that isn't applicable here. Using the correct flux and heat source (I use oxy-acetylene) and good technique, I have never had a failure . I have broken joints in a pro test rig and you can see the flow of the silver bearing alloy. NEVER a dry joint. I silver solder model steam locomotive boilers, hence I have a good supply of expensive silver solders! On very rare occasions I have used ordinary brazing rod and the correct flux. This too gives rock solid brazes, although it doesn't flow quite as well as the silver alloys. Stay-brite type solders are not good enough for the job in most cases. It has far less strength than silver solder or braze and I have seen loco boilers develop bad leaks around the fire box foundation rings due to its use, by shall, we say, less than well informed people. A metallurgist friend of mine looked at these failed seams and declared they were stress cracks throughout the soldering medium. If it isn't good enough for boilers pressed to 120 pounds per square inch, then it isn't good enough for us!
A couple of silver soldering rods doesn't cost the earth and you do not use much per joint, bronze rod is even cheaper so it really isn't expensive to use to use. A Map cylinder will last forever in this application. Why on earth risk a valuable plane that you have spent a whole lot of time building, for a few dollars "saved"?
I get plenty of practice at silver soldering and you need to do a few practice joints before doing the real thing, as long as the solder flows well, you know you have got it right. Too much is made of the acid flux residues, you have to clean the flux off, because it makes the joint unsightly. I then dip the joint in a commercial degreasing solution (cleans engines too!). If it is a boiler, then I "pickle" it in an acid solution (usually dilute sulphuric acid). not worth bothering about for non copper items.

Andrew.

[bob whitney]

  My 2 cents  i use stay brite for most of my important joints and haven't had a failure that i can blame on the solder .But i have trouble getting the heat where i want it  with Map and propane bottles .u use OXY/ACETYLENE  with a 0 or 1 tip to put the heat where i want it

[Brett Buck]

Silver-based alloys (those with silver as the primary element) all melt well above 842F and are therefore clearly brazing filler metals. Common silver based brazing alloys can have silver in range of 38% to 45% silver and melt above 1100F. Would not suggest such alloys for use on music wire since the higher temp required can induce brittleness unless heating can be controlled to avoid overheating music wire.

   That is a big issue and caused me some concern. At the suggestion of Derek Moran and Ron Burn, I no longer use music wire. I use air-hardening drill rod as per the post I linked to above. It's much softer than music wire and can tweak easily (intentionally or not) but it is much, much tougher. I did a comparison of the two materials and while it took far more effort to deflect the music wire, it failed at a hard spot after relatively few cycles. My arm got tired bending the drill rod back and forth (far into the plastic range) before the wire broke. I think the trade-off between stiffness, and the difficulty of re-tempering the music wire with home methods due to lack of process control, falls clearly to the drill rod.

    Brett

[Lyle Spiegel]

Brett, where do you get the drill rod? Is it available from Master Carr or similar?  Do you  buy a specific "grade" of the air hardening tool steel? Thx

[Brett Buck]

Brett, where do you get the drill rod? Is it available from Master Carr or similar?  Do you  buy a specific "grade" of the air hardening tool steel? Thx

  Yes, I got it from McMaster. A2 Air-hardening drill rod, as suggested by Ron Burn in an SSW post.

    Brett

[Tim Wescott]

  Yes, I got it from McMaster. A2 Air-hardening drill rod, as suggested by Ron Burn in an SSW post.

I'm just tossing this out:

If I'm correctly reading your posts here, and correctly recalling previous posts by you on this subject, you don't want the stuff to harden.

In this case, air-hardening rod may not be what you want -- you'd be a lot less likely to inadvertently harden water-hardening rod, and if you could get it, you'd be even less likely to have problems with something like 4130 steel (but I don't think you can get 4130 in 3/32 and 1/8" diameters, and I'm too lazy to look right now).  Folks use 4130 for things like race-car chassis specifically because it does not harden around a welded joint, so you aren't faced with brittle spots around welds, nor are you faced with having to heat-treat an entire chassis.

[Brett Buck]

I'm just tossing this out:

If I'm correctly reading your posts here, and correctly recalling previous posts by you on this subject, you don't want the stuff to harden.

In this case, air-hardening rod may not be what you want -- you'd be a lot less likely to inadvertently harden water-hardening rod, and if you could get it, you'd be even less likely to have problems with something like 4130 steel (but I don't think you can get 4130 in 3/32 and 1/8" diameters, and I'm too lazy to look right now).  Folks use 4130 for things like race-car chassis specifically because it does not harden around a welded joint, so you aren't faced with brittle spots around welds, nor are you faced with having to heat-treat an entire chassis.

     I don't care if it hardens as long as it doesn't have localized hard spots that cause breakage from fatigue. That's why you have to concern yourself with tempering music wire after brazing. You can't leave it soft because it's like coat hanger wire, so you have to try to harden it, then re-temper it to remove the brittleness. I have managed it OK so far, apparently, but it a very poorly controlled process that never made me comfortable.

    Brett

[Motorman]

Typical A2 steel drill rod has to be heated to 1725-1775 deg F and held there about 30 seconds while wrapped in foil to get hard. If the silver braze melts around 1400 and you back the heat off right away you won't harden anything. If you're worried about it, you can heat it up until it turns brown at about 500 deg F to draw any temper.


MM

[Mark Scarborough]

once again, I learn to keep my fingers quiet before jumping on a thread,, sigh,, well at least now I know

[NED-088]

.....And bronze isn't a filler material, brass is. Bronze is an alloy of copper and zinc (I'm pretty sure) and brass is an alloy of copper and tin

Close... :

Bronze

Brass

[Fred Underwood]

Is copper clad welding rod reasonable for control horn wire vs the air hardening rod?  It is soft steel, and seems similar to what I saw on Igor's site though he didn't mention the specific product.

Something like this, ER70S-2.

I have been using it, and after reading this thread, wonder if I need to keep my fingers crossed.  I have "generic" ER70S-2 from a local welding supply, but supposedly similar to this

https://www.fastenal.com/products/details/0864317

[Mike Haverly]

I've been using it for at least 12 years without a problem.  I use 7018 welding rod available at McClendon hardware here locally.  The bad news is that it is soft and bends easily.  The good news is that it is soft and bends easily, like to adjust flaps.

[Brett Buck]

I've been using it for at least 12 years without a problem.  I use 7018 welding rod available at McClendon hardware here locally.  The bad news is that it is soft and bends easily.  The good news is that it is soft and bends easily, like to adjust flaps.

  I wouldn't be too worried about it breaking, but accidentally tweaking itself might be an issue. That was a problem I had with the CSC horns that were very soft.

   Brett

[Mike Haverly]

Yes Brett, that is the caveat.  Good news bad news.  I've been using Radnor Safety-Silv 45 for the brazing.  The OP was about an inexpensive (I read cheap) product.  This is not that!  It works well though and I'll stick with it.  I thought about A2 but never did follow up on it.

[Andrew Saunders]

Call Tom Morris. I'm pretty sure he would explain to you how to do it. I have three planes with his control horns and they work great. Many flights on each plane and no issues.

[M Spencer]

These Horns have about THREE times ( at least ) the torsional resistance of the flash ones shown next .

The HOW To SOLDER lecture desapaired in the ethers  so if you DONT know what solderis , look it up .

Theyre salvaged from the Spitfires the tart trashed . Plumbers Solder comes in 50/50 & 60/40 ( hard ) BARS .

[M Spencer]

This is the current set up , in he Mewgull . Disconcerted about the horn flex. Will add the cut off arms at the root to minimise the bar length .
Elevators still marginal . all are 3 / 32 .

[M Spencer]

Viewed Under. The pushrods JOINED at the binding. Had to dither and so on to get the freedom of action ( realign the flap rods )
as was holding pushrod on leadout ( binding ) which didnt promise imunity from TROUBLE . All Free & clear now. Bit of a tight fit
with the diheadral as the bellcranks in the top of the wing .

[John Leidle]

  There is a lot of information here for me to digest.  My biggest question here is what torch or gas to use? I'm interested in the idea that Frank Williams posted but I have no idea what kind of gas or torch to use, I don't want to invest in a Ox-acetylene outfit mainly I'll not use it much & I don't have room to keep it.
    Any info is welcome,  john