Flex cable loose strand

[desmobob]

After four or five outings with my ProBoat Mystic 29, I have developed a loose strand (just 1/2" or so) at the motor end of my flex cable. I'm new to RC boating and I'm wondering if I'm over-tightening the collet....

Anyway, is the flex shaft toast (I already ordered a new one), or should I degrease it and silver solder the end? Is it even possible to get all the grease out so it can be re-soldered?

Thanks for any advice,
desmobob

[Steven Vaccaro]

You may be able to solder it.
Clean it with denatured alcohol and then sand and clean again.

[T.S.Davis]

This reminds me. I have never had any success getting solder to flow onto a flex shaft. Anybody know some tricks?

[Steven Vaccaro]

This reminds me. I have never had any success getting solder to flow onto a flex shaft. Anybody know some tricks?

If its black cable you will need a torch. If its gold cable you need a 40 watt iron for .098, .130 and .150, a 80 watt iron works better with .187.
I use the cheap weller irons. this one is great for thick wire and .187 cable http://www.all-spec.com/products/SPG80L.html

[detox]

Steve, Thanks for the tip.

[longballlumber]

Terry,

I use a HD Weller soldering GUN (not Iron). http://www.cooperhandtools.com/brands/CF_Files/model_detail.cfm?upc=037103475428

I also use the Stay Brite brand of solder. It comes with a acid type flux. It really helps to cut the grease and oil. Make sure you use a wet rage or some water to neutralize the acid when your done.

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXFS75&P=ML

Later,
Mike

[martin]

Soft solder for want of a better word is not the best way to stop flexes coming apart, Its better than nothing but the better way is silver solder ( brazing ) where you just literally spot the very tip of the flex so you dont put to much heat further down the flex. I done a Proboat one last week for a friend. You also dont get the difficulty getting it to take as you do on soft solder due to it not being ferfictly clean. Its very strong compared with soft solder. Martin.

[desmobob]

I have StayBrite silver solder and flux... that's what I'll try. One question I should have asked right off: since I have a new flex shaft on the way, is the existing one safe to run a time or two (one strand just standing out a bit loose at the collet end) or will I risk a total failure of the shaft and collateral damage?

Thanks again for all the help, gentlemen!

desmobob

[m4a1usr]

This reminds me. I have never had any success getting solder to flow onto a flex shaft. Anybody know some tricks?

I think all of us have their own "methods and materials" preferences. I like to use Eutectic solder, a combo of 96% tin and 4% silver. It melts at over 400 F and is pretty stiff stuff. But it does require a tipped torch to get enough heat onto the steel flex. I start by cleaning the end with carb cleaner (mostly acetone, Tolouene and or methyl ethyl keytone). Then use a decent flux. Solder just enough of the flex under the couplers gripping surface. Shouldnt extend beyond. Once its cooled put the stubb shaft in a drill and spin it. Using some 160 or 220 grit sand paper grip the soldered end and let it reduce the solder that may extend beyond the flex outer diameter. If you dont do this last step the coupler may not seat or grip well and if you use 60/40 solder the lead can act like a lubricant against the coupler grip.

I like to braze them too with silver solder but dont have that type of setup at home so I have to drag it to work. Lately I have been happy with eutectic solder. It has no lead and comes right off leaving the steel strands of the flex showing. You can wash the soldered end in soap and water and dry it off before relubing for use. Just my prefered method.

John

[Andris Golts]

The most effective method i have found for brazing flex shaft ends after de-greasing with acetone is heating the tip of the flex shaft with a plumbers propane torch then dipping the end of the heated flex shaft into ESAB Duzall soft brazing flux found at most welding supply stores with a 1oz of flux poured into a clean glass container once pulled out of flux wipe with clean rag and repeat this several times until end is cleaned then i dip in flux for the last time and a small dab off stay-brite 5% silver solder i only let the solder seep up the shaft about 3/8'' and re-grease soldered area as soon as the shaft cools as this flux is corrosive i have used this method for 12 years and never had a problem.Regards Andris Golts.