I solder 10ga, I just use a different tip. Large flat one that holds more heat.
Personally I can’t (19V 80W laptop charger with thin tip iron delivered with the spot welder). I keep a basic non regulated 75W for this purpose.
Yeah the smaller tip can’t handle the heat dissipation with large ga wire
I solder often 8awg and did 6awg once
got the welding pen for sunkko 709a welder and rigged it to work with the boss welder.
i’m loving it so far, and tips are trivially easy to replace.
oh, the tips are spring loaded so you can apply nice, even pressure on the tips, yielding very nice results.
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Really nice ! Did you tweak the pen other than soldering a XT90 on its leads ?
that’s the only thing, replaced the bullets that it comes with xt90.
pen is a bit pricy though, about $50 shipped or so.
$50 seems expensive?
agreed. did it for science. and convenience.
Does the spring loaded system bring a real added value on the spot quality compared to the included pen of the boss welder ?
as of now, since it’s new, i’m finding it kind of cool to have. maybe the novelty may wear off after some time.
the real benefit is there is solid contact across the two probes even if you don’t apply even pressure. like a suspension, it levels itself. so the welds are coming out more consistent than solid probes.
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My wording was poop, I wasn’t trying to saying you overpaid. It was more like it’s a bummer they are $50. It looks like a sweet pen.
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No i didn’t
My pen is not the same model. Sunkko and 50$ too yet not the same. The screws broke on the first day. I put better ones and the threads broke too. The metal is like butter. Xtreme low quality. The tips come out all the time. They move left to right spoiling the welds… Worst investment ever. Any of my other pens are way cheaper and better. But i repeat. Not the same model. That pen of @thisguyhere could be perfectly fine.
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Heyyyy! I had one of those 2 years ago! 
(Dont miss it lol)
Definitely. The electrodes wear unevenly so having the spring helps you apply the same pressure without placing the pen at a weird angle. The even pressure always produces a better weld. It’s also useful for getting welds done in awkward spots at awkward angles.
@Erniechan and @rojitor I have the exact same pen as @thisguyhere and its quite good. The electrodes on it are kinda crappy so I used replace them immediately with electrodes from PowerStream (Also where I sourced nickel)
@rojitor, have you had any better luck with copper welding? have you tried tungsten electrodes? What is the max thickness you can do? I’m thinking of getting myself one of these now to do copper packs manually when my CNC machine is too busy or with really hard to handle packs
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Imma need a link on this.
/edit
got it.
https://www.sunkko.net/sunkko-70b-spot-welding-pen-for-battery-pack-709-series-appropriate.html
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Yes i have tested tungsten. It sucked. The Max i did is 0.2 but It is very dangerous for machine and user. I have stuck to 0.1 copper.
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