How-To: Add Copper Braid to Springs

thx that’s damn good results. Are those results only expected when running higher currents say 3.5A and above? And what would you attribute the gain to? Copper being a better conductor? the flat braid being the best pathway, and also bypassing the spring which might behave like a coil? or combination of both?

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There are so many to choose from, do you have a link to that one?

I’d recommend 2.0mm wide.
https://www.fasttech.com/products/1004/10002730/1202500
From the pictures, it looks like it has no flux. I got mine with my hot air reflow station kit.

PyTech - thx that’s damn good results. Are those results only expected when running higher currents say 3.5A and above? And what would you attribute the gain to? Copper being a better conductor? the flat braid being the best pathway, and also bypassing the spring which might behave like a coil? or combination of both?

Well, this is all about the high Vf of an XM-L2 on copper, so, all resistances are bad with this setup, and yes, probably only a big issue like this at high amps. Springs are typically steel coated with something (hopefully), maybe silver. Steel is not an ideal conductor and depends on the quality of the spring, and in budget lights, you're not gonna find quality springs with a good amt of silver.

I was fiddling around with a light today. I didn't feel like doing much, so I figured I'd add some braid to the tailcap for something to do. When I took it apart, it wasn't much of a switch. A loose spring resting on an aluminum contact all held together by the brass cap torqued down with a nylon washer. Non of my extra switches would fit in the setup, although my McClicky was just a hair away from threading in perfectly.

Since it was apart, I added braid to the spring. I know relic didn't find those brass spring caps to cause any real impedance, but I thought, copper must be better than brass.

I drilled a hole through the brass cap and stuck a piece of 20AWG wire through the hole. Next I separated and splayed out the wire strands so they would mash up flat against the inside of the cap, added flux and heated up the cap. I let the solder bubble and pool evenly and then get sucked up the wire through the hole.

Looks good. Snipped off the excess, ground it flush with the dremel and used the buffing wheel with some knife stropping compound.

i know it really won't have any effect on this particular light, but I like the idea af having the battery contacting copper, which contacts with the braiding on the spring. I'll try this with my builds where I'm trying to tweak things max and mininamalize resistance. I guess you could also take off the brass cap and throw it away. Next time I'll try it with 14 or 16 AWG wire. It can't hurt, and gives me something to putter with.

That is a good idea! Thanks for sharing it!

Tom are you saying soak in acetone then alcohol to prep braid prior to soldering?

Yes, that's what I've been doing to remove any flux that may be in the braid. I'm still not happy with the braid I'm using though - don't feel confident it will hold up in the long term. For some tailcap springs that don't compress much, it's fine, but doing a Shocker battery carrier where compression is extreme with long protected batteries, it takes a beating... I've switched between KP 3400's and Pana PD's, and the difference is extreme with those springs - Pana PD's barely touching it seems like, KP's just about fully compressed.

You could try flexible silicone wire attached outside the spring. I found the spring compression very tight with protected Panasonic 3400 and Sanyo 2800 in the carrier of my EYE40. I found these protected Panasonics fit nicely.

Interesting, I should try those. But I'm trying to be universal - I don't own a Shocker, but mod'ed like 8 of them, so figuring the KP 3400's are worse case. Silicone wire on the outside might be better in a wrap-around setup, not straight up-down (too much flexing on the solder connections) -- maybe I should try that...

No to poor cold water on this thread but it is an old tecneque used on hot rod mags.

The thread isn’t about innovation, its a “how to” thread.

Would these silver plated copper springs be a good alternative to copper braiding?

I think they will be OK. Berillyum copper is considered toxic (dust and fumes, not solid metal), so the silver plating serves two purposes. I think I have some uncoated ones and I don’t bother with braid on those. If I can confirm they are b-copper, I’ll post a link.

THE-day, the ones you linked would need to be cut shorter, they would be unstable at that length. I would guess up to 1/2 inch or so would be OK, maybe just cut in half.

I did it on my KDC8 and my solarforceL2N tailspring thanks for posting thread on thisn I did with out any major calamities befalling me or poor light thanks again.

I like how you did this on the light i won in your give away, its one of the most powerfull single XM-L lights i have now. :slight_smile:

DenB, I received my replacement F13 that I bought a while back, after the giveaway. It was DOA… I took it all apart and put it back together. It is fine now. :~
Doesn’t matter much, since I’ll replace most of the guts with new guts.

They’re properly called “Flush Cutters”. These are made of plate steel, bent and sharpened in all the right places. At some point, at the moment you cut a wire, one of the jaws will fly off with a pop. It won’t hurt unless it hits you IN the eyeball, but it’s going to happen.

I use these at work to cut Cat5/Cat6 ethernet cable and occasionally other low-voltage copper cables. The plate-steel arms fail right at the edge of the hinge. Since it happens at the moment of greatest impact in a cut, the result is quite violent, for such a wee bit o’ metal. The flying jaw still has a sharp point and edge, but they don’t tend to fly too far so I doubt they’d stick into anything. They’re cheap enough, I don’t even bother with returning them “under warranty”, usually.

If you’ll invest in a bigger, tougher “semi-flush” cutter, it will handle all but the finest flush cuts, which will be done by this one, all of which will extend this one’s lifespan significantly.

If you take care of a good set of flush cutters, they can be a most awesome tool, regardless of the price… (try it — gently — next time you get a stuck splinter or metal shard…)

+1 on this suggestion!

Thanks relic38, after I posted I realized they weren’t the perfect size.
Well I was able to find some silver plated copper springs on an old CPF thread which are the right size.
I’m hoping there are still some left.

Btw, whats your opinion on stiff gold plated springs? Are they good enough to reduce resistance?

The stiff gold plated springs are usually steel-based. Very high resistance. The gold plating does help a, but mainly prevents rusting. After testing them, I end up putting braid on them.
Edit: I modified this statement slightly based on the test results below.