Field Winding Failure

[rcavictim]

When trying to solder aluminum to aluminum with common lead-tin solder, flux should not be used.  The rosin flux in the joints you soldered may cause loss of good metal to metal contact now and other troubles like corrosion in time.

[vdubnut62]

RCA, he was soldering stranded copper to aluminum, a job I don't envy!
Ron

[Wizard]

Another tip is get extremely fine sandpaper and high temp oil.  Oil coat wire and sandpaper, sand and don't clean off the oil on the aluminum.  Solder through the oil film.

Cheers, Wizard

[OilCan]

Another tip is get extremely fine sandpaper and high temp oil.  Oil coat wire and sandpaper, sand and don't clean off the oil on the aluminum.  Solder through the oil film.

Cheers, Wizard

Interesting, haven't heard about that one.  I ended up rosin-fluxing the pretinned copper stranded to each
aluminum lead with 60/40 and then sleeved it all with heat-shrink.  I sanded clean the aluminum wire before soldering.

Pulled reasonably hard on the joints but they seemed to hold.  Each pole measures 7.4 ohms at the new leads.

Will also be adding a 5A slow-blo in the field circuit.

[mike90045]

Wasn't easy soldering the tinned stranded copper wire extensions to the aluminum pole wires.
Sanded the ends and rosin fluxed then covered the splice with heat shrink.

I'm not aware that any solder/flux will work with aluminum wire. I've seen some weld rods pitched at home shows, that can braze aluminum, but not solder.

[mobile_bob]

Mike:

i too have never heard of soldering aluminum to copper, at least not using common 60/40 rosin core
although i am sure one might get a solder joint that "looks" good, it is hard for me to imagine that it
will actually be a good solder joint over time.

however just because i have never seen it, or never heard of it being done, isn't reason to believe it is impossible
i guess.

i would just have to see it to believe it myself 

if i had to bet my lunch money, i would bet on the side of the joint failing much sooner than later.

i would be more apt to secure and seal a good mechanical connection with jb weld and cover with shrink tube
than trying for a solder joint using rosin core solder.

anybody got a link that illustrates soldering copper to aluminum wire?

bob g

[rcavictim]

I got a personal tour by the president himself of a prominent US electronic capacitor manufacturer's plant in Chicago.  I learned that after the capacitor roll comes off the rolling machine with one aluminum plate protruding from one end and the other plate protruding from the other the tinned copper flat connector strip was soldered to each end of the capacitor roll by using non flux lead tin wire solder like a plumber uses.  The soldering iron was a big industrial American Beauty with an aluminum tip installed.

[OilCan]

I am almost tempted to redo these connections by getting #18 aluminum wire
and connecting the pole pieces with compression rings at the joints.  The solder
alloys and dielectric corrosion potential between those metals doesn't give me
much confidence either.

But then I'm still left with the problem the slip-ring connections are copper...geez.
Best I can hope to do is make a mechanical joint there as well.

My last option would be to take all four pole pieces in to the motor shop and have
them wound with copper.  So far I've put back in $180 in this head by getting stator
dipped and baked, new bearings and metal fan.

Leave it to the Lamers at Tawasi  to assemble their heads with mixed metals.
Again if anyone ever ships you that brand of gen head send it back!

Thanks for your comments.

[mike90045]

KESTER:

"" Alloys with melting points above 1000°F are also used to join metals and are sometimes referred to as solders, or hard solders. Actually that process is brazing, not soldering, and this entry is not about such materials.

Copper, tin, gold, silver, platinum and palladium are easily soldered, nickel and brass a bit less so.  Cadmium, lead and bronze are still harder.  Finally, zinc, steel, and stainless steel are very difficult to solder.  Aluminum cannot be soldered with tin-lead alloys, but can be with a barium-aluminum alloy at around 750°F, while continuously scrubbing the surfaces with a stainless steel brush to remove oxide.  Only certain aluminum alloys can be "soldered." ""

METALWORKING FORUM:
http://newsgroups.derkeiler.com/Archive/Rec/rec.crafts.metalworking/2005-09/msg00977.html
  excerpt 
Harris Staybrite is 96% tin, 4% silver. They say it'll stick to
aluminum with a special flux, but my welding store doesn't carry the
flux so I can't vouch for that. It will also stick to brass,
copper, steel and stainless.

Allstate "Strongset 509", a zinc- cadmium alloy, will join aluminum to
aluminum, also to copper, brass, steel and stainless steel. It's
quite strong at 29,000 PSI. It's pricey. The flux is organic and
burns easily. This stuff works very nicely if one can avoid burning
the flux. If the flux burns, it's a mess: clean up, start over.

--

IN MY EXPERIENCE, trying to solder with electronic solder tin/lead/rosin you can eventually get something that looks like a solder joint, but internally, it's just flux gluing the wires together.
Mike