Solder for flex shaft ?

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Chris Davis

Well-Known Member
Joined
Jun 27, 2013
Messages
329
I have a new flex shaft I am trying to solder. I always use ezflow silver solder. Nothing I have sticks to this thing. The flex shaft is black in color and when wire wheeled is silver looking.

Has anyone ran into this problem? Any ides would be greatly appreciated.

Thanks in advance

Chris
 
I use some fine grit sandpaper and rough up the area I want the solder applied. I believe I've used 350-500 grit with good results.
 
The flex shaft may have a lubricant on it. Clean it with Brake Clean first, use a good flux and then solder.
 
Chris, Soak the end of the cable in muriatic acid.. about 5min and your end will be ready to solder.

grim
 
The cable is new and have tried cleaning with brake clean and sanding before soldering. I will try the Muriatic acid. I am a welder by trade. Soldered many flex shafts, this one is just giving me trouble.

Thanks for the ideas

Chris
 
If you are talking about the loose end of the cable I would not solder it. I know this goes against every thing you have heard. But to solder that end will lock the conductors from moving. This will cause the shaft to break in time either at the stub or the motor. What happens is when you place the shaft into a shaft log tube with a little bend the conductors try to move but can not and will bend back and forth like a coat hanger and break. I soldered shaft 30 years ago and they all ways broke. Started making shafts at that time started to understand what was going on. I have shafts that are over 20 years old that I still run. The shafts that are in my twin have been in over 20 twins and I do not know there age.

I manufacture the SST shaft that you may have or have seen around. And I will replace any shaft that breaks in the stub weld so long as it has not been soldered on the other end.
 
Mark,

Have you ever had the strands come loose and peel back at the collet? Just wondering because that is why we have always soldered ours but what you said is very interesting.

Dave
 
What I have seen is some of the collets close up so bad the you can not get the shaft back in after you remove it. Then I see racers hammer them in and this is what pushes the outer strands back on the cable. Grab the end of the cable and twist it counter clockwise and pull at the same time and the outer strands will come back out to the length of the others in the cable. To fix the collet take the insert out and use a screwdriver to open up the collet. Then the cable will slide back in.
 
The shafts in my scale boats are soldered at the prop end and are free floating square at the engine while smaller boats use the round collet at the engine. If one breaks, it would have to be due to the prop fouling on something rather than due to flexing and bending
 
I use Sta brite i think may still be available on ebay... its the only silver ive had will flow and stick.. but as mike stated( acid) it comes with a bottle of acid to use for flux and it works... i presoak my cut end in acetone first for grease also.. the black crud in my experience comes from overheating when you solder and if it gets that far i junk it... because itll break in time right there... good luck...
 
After u clean the end warm the shaft on the end u are going to

Soldier then brush some flux on it then get it ready to apply

The soldier when it's the right temperature it will flow in to the

Cable like water then let it cool off get the end ready to go in the stud shaft put the 2 together then warm the 2 up together brush on

Flux when it is at the right temperature apply more soldier the 2 will bond instantly but I always used silver bearing soldier
 
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