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Replacing part of SK3 phase wires with silicone wire vs Extenders


#21

I’d go with 14 or 16awg as it’s smaller and will be easier to solder. Phase leads also don’t matter as much current wise as battery leads


#22

I found that unity uses 14AWG. So I guess I will get something around that. 1.5mm2 inner, 3mm outer is the closest I could find…


#23

Where are you buying from? Hobbyking has some good silicone wire in almost all sizes


#24

Good shop for Germany/EU, but for you Australian guys, dunno, guess hobbyking is your source.
https://www.ebay.de/str/modellbaucityeu


#25

Your thread is 3rd in search :slight_smile:


especially this post and this post


#26

Sadly those two posts don’t emphasize on soldering temperature and length of the cut…

So to continue my topic:

How do I prevent enamel melt from soldering if I want to do a “butt joint”?

Do I aim a blower fan at the wire?

I do have leaded solder both 70/30 and 66/34, but my sacrificial motor still gets molten enamel deeper down the wire.

Another option I am consider, offered by my colleague:

Solid copper crimp.

You take a copper tube for crimping, just the right size to perform a butt joint, smush the wires together inside of that and crimp the heck out of it, causing a pressure weld between the copper strands, but leaving me with some nasty copper cylinders…

I mean it’s kind of the same as a butt joint, but safer for the enamel…? Maybe not as a reliable?

Waiting for opinions/experience. :slight_smile:


#27

Typically you’d clamp on something to sink the heat if you don’t want it to travel past a certain point. Like this:

But the wires are so beefy and there’s so much heat. Maybe mini locking pliers? No idea if this would be effective at all.

And of course a hot iron with a huge tip, in and out quickly (do as I say not as I do lol).

This can be good but you have to get it perfect. With meaty thick wires and very tight access I don’t know how you’d get a proper gastight crimp.


#28

I figured to put some copper plates and a blower fan directed at the place I don’t want heat… but… these windings transfer heat in a flash, literally. Heatshrink that is there originally saves the heat in windings from cooling down so hard I can’t even… This explains why original connectors have at least 5cm of solid wire that is definitely melted together right after them from soldering…

For gastight crimping, I think I’d have the space necessary, but it would mean leaving more original wire in crimping tube length intervals, I mean it’s still better than the original non bendy cable…

Need people with experience asap. :smiley:


#29

I dont rly get what the problem is. Are you worried the cables start to rust if they loose the enamel?


#30

I am worried by the fact that the heat seeps into the motor and shorts the phases(by melting the enamel) before I can say “oops”.


#31

well the soldering itself just takes a couple of seconds, no worries there.


#32

What wattage is your iron?

Trust me, if it’s around 50 you’d have to TRY to melt the stuff further down the line.

Just give the shortened enamel wires an initial tinning, tin your silicone wires, and then solder them together. With the wire sinking heat from both ends you’re going to be fine.

Are you using 12 guage or 10 guage?


#33

My iron is 150W, sharp tip. Adjustable up to 460’C.

My wires are in fact 14AWG.

What temperature should I aim for?

Maybe I didn’t clean the enamel well enough or something on my sacrificial motor, as soldering took me at least 10 seconds while feeding inhumane amounts of solder into the joint. Pre tinning sounds like a good idea, but this kind of avoids the butt joint idea being flush.


#34

A soldered butt joint is not going to be mechanically sound.


#35

What do you mean by “not being mechanically sound”? Prone to breaking, corrosion or something else? I can’t catch the wordplay. :slight_smile:


#36

Prone to breaking.

I think the best option would be to evenly splay your stranded wire, around .75" of uninsulated, evenly ‘encase’ the solid core wire with it, then with a sturdy yet flexible enough piece of other wire, tightly wrap the joint and then solder, making sure the entire assembly properly wets.


#37

But that’s the “butt joint” I was talking about all this time. :slight_smile:

I think I will attempt airtight crimping, somebody has to try it, for science!

Will grab some 1.5sq.mm/2.5sq.mm heat insulating(glue) tinned copper crimp tubes and get to work with crimping pliers. Best case scenario - it works and I didn’t have to heat anything up much. Worst case scenario - I can still solder to what’s left.


#38

Hmm. Either you’re not visualizing what I said correctly or one of us has a misunderstanding of what a butt joint is.

By soldered butt joint, I thought you mean placing two faced ends together, aka ‘butting them together’ . You would have a tinned end of your solid wire, a tinned end of your stranded wire, and melt those two ends into one, on the flat circular plane of each. Which would lead to having a flaccid weiner like something.

What I advised to do is a bit more mechanically secure. Technically you’re still something close to butting a part of it, but by no means would it be a flush cylindrical connection


#39

I think we’re talking about the same thing. I just call it a “butt joint”. A spliced, pushed through each other cable join that is wrapped around with a strand of copper wire and then flooded. :smiley:

Like in this video:

This causes my back to shiver though, because the enamel will NOT survive after I shorten the original winding cables and attempt to flood the new connection so well that it shines throughout.


#40

Okay, we’re at least on the same page of the quality/process of the joint. I actually think this video is where I learned how haha.

I think the confusion just lies in terminology.

When I think butt joint, like, you have a butt connector with an ID that goes over your wires of presumably a similar OD and then crimp it over. The process of the two ends touching together is the ‘butting’ aspect.

So when you talked about soldering it, I just thought you were going to strictly attach the ‘end to end’ almost as the 'side to side’s in this video would be.

But anyways - crimping might be a great idea if you can get a small piece of piping to go over them. I have the cheap yellow China 16 ton for $40 crimpers that flood Amazon for my 00 welding wire and it turns joints into solid fuckin copper

p.s. I’ve also been up for way too fuckin long maybe I’m dickin up