Control Horn and welding wire: pay attention

[Massimo Rimoldi]

Goodmorning everyone,
I apologize for my bad English but I hope you understand the same.

I am planning the construction of my next model.
For the realization of the Flap Horn I thought to adopt the Igor system and use the copper-coated 1/8 "welding wire.
The idea attracted me a lot but before realizing a definitive Horn, I thought to do a test, using a piece of wire, a simple iron plate and as a flux the rosin I made a sample to do some destructive tests .
At this point I blocked the plate in the grip and I tried to bend the stem ...
Surprise, almost immediately the soldering gave way but on closer examination I realized that the copper deposited on the welded rod portion had been delaminated and the rod was now free to rotate .
I then did a second test (with the same result) and the photos show the situation before and after.
Since I have no news that this has happened to others it is possible to think that the wire in my possession are faulty, but in any case the copper is not there to be used as an interface for a welding.
Later I made a test by removing the copper from the welding area with abrasive paper and I welded using an acidic flux.
In this case the joint has resisted all possible tortures.

Regards, Massimo

[FLOYD CARTER]

So called "piano wire" steel wire from hobby sources seems to work the best.  Welding is not advised, due to annealing of the wire.  Brazing is very strong, at a lower temperature.

[Dave Hull]

Great info. Thanks!

[Tim Wescott]

I had that happen once or twice, a long time ago when my dad owned a body & fender shop and liked to use copper-coated welding rod.  That's about the time I actually started spending money (oh, the horror!) on music wire from the hobby shop.

I tried a quick web search on the bond strength between copper plate and steel -- I suspect it varies a lot depending on the process used and the care taken.  Since the copper plating on welding rod is there for corrosion resistance before welding, and maybe to add some copper to the weld during, the actual strength of the bond isn't going to be important, so it wouldn't surprise me if it varies all over the map.

[Mike Haverly]

OK, I use 7018 welding rod all the time, no issues.  I sand the copper coating off and braze Safety-Silv 45.  I've tried to break the joint and the wire itself fails first.  1/8 on the flaps and 1/16 on the elev.  Use your choice, this works fine.

[Dan McEntee]

OK, I use 7018 welding rod all the time, no issues.  I sand the copper coating off and braze Safety-Silv 45.  I've tried to break the joint and the wire itself fails first.  1/8 on the flaps and 1/16 on the elev.  Use your choice, this works fine.

  1/16" horns on an elevator???

   The only reason, as far as I know, that welding wire is coated with copper is to help prevent rusting before use.

   Type at you later,
    Dan McEntee

[Mike Haverly]

OOOPS!  Yeah, 3/32 on the elevator.  ASFAIK copper is to resist rusting. 

[Istvan Travnik]

My humble opinion is to forget forever soldering/welding of  junctions being under torsion load.
Why to play poker with God / Fortune?
I solve this junction for 37 years like this:
https://plus.google.com/photos/117790355930193335731/album/5715088163776972593/5731000107701851922
to:
https://plus.google.com/photos/117790355930193335731/album/5715088163776972593/5731000495013276018

Remark: forget the expocrank on these photos, only the horn + lever junction is relevant now.
Istvan

[Igor Burger]

Goodmorning everyone,
I apologize for my bad English but I hope you understand the same.

I am planning the construction of my next model.
For the realization of the Flap Horn I thought to adopt the Igor system and use the copper-coated 1/8 "welding wire.
The idea attracted me a lot but before realizing a definitive Horn, I thought to do a test, using a piece of wire, a simple iron plate and as a flux the rosin I made a sample to do some destructive tests .
At this point I blocked the plate in the grip and I tried to bend the stem ...
Surprise, almost immediately the soldering gave way but on closer examination I realized that the copper deposited on the welded rod portion had been delaminated and the rod was now free to rotate .
I then did a second test (with the same result) and the photos show the situation before and after.
Since I have no news that this has happened to others it is possible to think that the wire in my possession are faulty, but in any case the copper is not there to be used as an interface for a welding.
Later I made a test by removing the copper from the welding area with abrasive paper and I welded using an acidic flux.
In this case the joint has resisted all possible tortures.

Regards, Massimo

  never happened to me and I always test them before use, I did not know welding rod can have such fault, good adwice. I see it needs attention.

When I did destruction tests, I was able to turn horn 360 degrees before it failed. Turning is visible on twisted material on place of failure.

I would say, use rods from another maker. Test and when you see it is OK, use. And do not forget to test it before use, you must be able to bend in angle, you will need it at trimming.

[Massimo Rimoldi]

  never happened to me and I always test them before use, I did not know welding rod can have such fault, good adwice. I see it needs attention.

When I did destruction tests, I was able to turn horn 360 degrees before it failed. Turning is visible on twisted material on place of failure.

I would say, use rods from another maker. Test and when you see it is OK, use. And do not forget to test it before use, you must be able to bend in angle, you will need it at trimming.

Hi Igor,
established that there is the possibility of a failure, and not being able to subject all the horns to destructive tests, I will opt for the removal of the copper and the use of an acidic flux.
If, after welding, a thorough rinsing with water and sodium bicarbonate (or ammonia) is performed, the chances of the joint having corrosion problems are really remote.
In any case, the presence of copper that does not completely cover the iron surfaces (the horn are not plated) is a sure source of corrosion.

Massimo

[Brett Buck]

A2 Air-Hardening Drill Rod:

https://www.mcmaster.com/#drill-rods/=1dbb9rv

   Brett

[Gordan Delaney]

I`ve been using welding rod for 40 years.

Gordy

[Mike Haverly]

Igor's picture resembles my results.  Plenty strong, just has to be sanitary when making the joint. 

[Massimo Rimoldi]

A2 Air-Hardening Drill Rod:

https://www.mcmaster.com/#drill-rods/=1dbb9rv

   Brett

Hi Brett,
thanks for the imput.
I know "A2 Air-Hardening Drill", unfortunately I have never found (in Italy) a source for small quantities.
About three years ago I placed an order from McMaster, but the order was canceled and at my request for information they replied that they were not interested in new international customers.
My purpose is to find an alternative to the use of the piano wire because of the unknowns posed by the need to harden the wire after brazing.

Massimo

[Lauri Malila]

Massimo,

Is this drill rod same as what we call silver steel? It’s easy to bend in soft state, and it’s also easy to anneal after brazing to eliminate brittleness. L

[Brent Williams]

You might inquire with Grainger.  They do ship and/or partner internationally. 

https://www.grainger.com/content/worldwidepage

.125"   https://www.grainger.com/product/GRAINGER-APPROVED-Air-Hard-Drill-Rod-33J238

.093"   https://www.grainger.com/product/GRAINGER-APPROVED-Air-Hard-Drill-Rod-33J240

(Thankfully, I was able to just drive over to the local Grainger branch and pick up my order.)

[frank williams]

You metallurgists have to help me here.  What is air-hardened drill rod and how does it compare to K&S music wire?   The term "drill-rod" makes me think that it is very hard and brittle.  However "air-hardened" implies that it might be annealed somewhat by air cooling.

[Massimo Rimoldi]

hello Lauri,
A2 Steel and Silver Steel have a similar Carbon content but A2 has higher percentages of Chromium and Manganese.
the great appeal of A2 is that simple air cooling makes it a satisfactory condition.
Silver Steel could perhaps adapt to the purpose.

For Frank,
thanks for the information, really appreciated.

Massimo

Typed later:
I apologize to Brent, I wanted to thank him

[Brett Buck]

You metallurgists have to help me here.  What is air-hardened drill rod and how does it compare to K&S music wire?   The term "drill-rod" makes me think that it is very hard and brittle.  However "air-hardened" implies that it might be annealed somewhat by air cooling.

  It is not brittle at all, unless you intentionally make it that way. Not as stiff or springy as music wire but much, much tougher and doesn't have any problem with hard spots when you braze it. Much better and safer than music wire.

       Brett

[Phil Krankowski]

A2 is an air quench alloy that includes chromium and has about 1% carbon.  It is shipped annealed typically.   Heating above 1450F (cherry red) followed by an air blast quench will harden it, after which it must be tempered.

With a low temperature brazing process that does not reach 1450F the metallurgy does not change.  The steel remains "annealed" without hard spots or brittleness. 

There are lookups for European equivalent alloys.

http://www.steelnumber.com/en/equivalent_steel_iron_eu.php?zname_id=636

Phil