Unable to solder motor cable


I have a damaged motor wire from my 65161 that needs to be extended
I bought some cables but I am unable to tin the motor wire (no problem with the AWG 8 silicone cable I got)

so far I tried:
-scraping with utility knive
-gas torch

but the wires won’t accept the solder.

what should I do?

Did you use flux? Usually scraping or sandpaper followed by acetone and a good amount of flux. I have better result with a 80W solder

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thank you, I will try with flux. usally I don’t need it but probably these wires are to oxidized

Yes mate I don’t think I could have done it without flux

In the worst case you can dip wires in a molten NaOH salt bath and get rid of both oxidation and whatever type of insulation but it’s a last resort, fumes are highly toxic and the NaOH will dissolve anything it gets on - including your flesh. Wear protection, do it outside etc.

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Nothing doing, neither with flux nor NaOH, nor both

I’ve had to do it on class H dual layer polyesterimide enamel wires that was impossible to clean otherwise. As said, it’s a last resort, i don’t think the common motor wires need it.

didn’t work. dont understand it.

maybe I should try with phosphoric acid as there is rust (even if I don"t know where that should come from).

ordered a new motor, maybe If I find the time I’ll open the old one and try to replace the cables

But did you melt it? Gas burner, a bunch of NaOH granulate, heat in a disposable tin can and add a teaspoon of table salt, heat ’til salt melts. Dip wires until clean.

no, i just made a strong solution of caustic soda. seems I got you wrong, took molten for dissolved.

on the weekend maybe I find time ( and place ) to try it safely

Ok, take care. That mix is truly dangerous, use full clothing, gloves, glasses/goggles, any fumes inhaled will damage your lungs seriously.

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Could you document your journey ?

Today I tried the molten NaOH.
heated it up in a Tunacan on a camping stove

stirred with a wooden chopstick and dipped the cable forbsone time, then rinsed it with water: looked good

Much better than before, but still some spots that didn’t get tinned. in the picture on top a new cable for comparison

it is working, but probably needs thorough preparation I hadn’t time for today

And do it outside, the fumes are nasty

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Wear swimming goggles and a good vapour mask.

Yeah, it’s hard to separate the wires so that the salt can reach each properly with some circulation. Still beats trying to scrape 500 thin wires😀

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