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Which spot welder control board to use?
#11
Quote:I still need a few bits:
-secondary winding wire, which will be recycled
- flexible leads - not sure where these will come from


You can make these from the existing secondary.

First, you have to unwind your secondary. This'll take a long time, since it's 2000 turns. Wrap cardboard around the leg of a chair, and then spear the leg of the chair through the secondary so that it uses the leg like an axle.

You can clamp a steel bar into a power drill, use an end-stop (so you're not holding it with your muscles) and run the drill so that it yanks the secondary wire and slowly re-spools it onto the steel bar. It'll be tough at first until it breaks through the outer layer of enamel. It'll break a bunch of times, that's okay.

Once you have a spool, you can re-spool it the right length. Place two pieces of wood the distance apart that you want the length of your secondary to be (~1 foot per turn, howevermany turns, plus two feet for leads). Then just wrap it around and around those two wooden pegs until you've used up all the wire.

Then twist the cable you just made so it doesn't unwind, ziptie it at the ends, and then cut, flux, and solder them.

Now you've got a flexible copper cable you can use as wire for your new secondary.

Spot welders are the hardest to do this with, since you won't have much extra wire to work with (you took material that was tightly wrapped around the core, and stretched it out an extra 2 feet, probably cutting the cross section to 1/2 or 1/3). But it works.
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#12
Thanks for the suggestion Matt, however I cut the secondary wire, then hammered the remains out, so there is no way that wire is being reused...
I will be giving that copper to my electrician friend to take to the recycler.
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#13
(12-07-2019, 11:18 AM)Oz18650 Wrote: Thanks for the suggestion Matt, however I cut the secondary wire, then hammered the remains out, so there is no way that wire is being reused...
I will be giving that copper to my electrician friend to take to the recycler.

I personally prefer to work with a DC based welder for safety reasons.
I don't trust the AC method and a cheap non-Certified Chinese board with my life or that of my cat Angel

So I am looking at the DC route.  This board --> https://www.aliexpress.com/item/40004248...f00bc64e8a

comes with everything you need and has an adjustable power level (so it says).
The FETS on the board are 300A capable each.  Although there are more of them on other boards like what was said.... the others don't appear to have weld power control.  Just automated pulse timing. 

I have contacted a seller and am waiting for a response.   The one seller said they have a version with programmable pulse width along with auto pulse.  They were checking on if it was available to me still.
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#14
(12-07-2019, 03:23 PM)Bubba Wrote:
(12-07-2019, 11:18 AM)Oz18650 Wrote: Thanks for the suggestion Matt, however I cut the secondary wire, then hammered the remains out, so there is no way that wire is being reused...
I will be giving that copper to my electrician friend to take to the recycler.

I personally prefer to work with a DC based welder for safety reasons.
I don't trust the AC method and a cheap non-Certified Chinese board with my life or that of my cat Angel

So I am looking at the DC route.  This board --> https://www.aliexpress.com/item/40004248...f00bc64e8a

comes with everything you need and has an adjustable power level (so it says).
The FETS on the board are 300A capable each.  Although there are more of them on other boards like what was said.... the others don't appear to have weld power control.  Just automated pulse timing. 

I have contacted a seller and am waiting for a response.   The one seller said they have a version with programmable pulse width along with auto pulse.  They were checking on if it was available to me still.
Cool.
That could be another good option for people to use.
Please let us know how your spot welder turns out.
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#15
Oz Wrote:however I cut the secondary wire, then hammered the remains out, so there is no way that wire is being reused...

Ahh, this is the one bit of advice of mine that many people didn't take, so just about all the tutorials out there say to just cut it off :p. A shame. When I first made my tutorials, I said to remove the secondary intact, but didn't say why. It was supposed to be revealed in later project-specific videos that I only ever half-filmed and never finished.

Bubbs Wrote:I don't trust the AC method and a cheap non-Certified Chinese board with my life or that of my cat

It's all done on the primary side. The worst thing that can happen is that the spot welder locks on. The output of a transformer based spot welder is still lower voltage than an AAA battery.

Meanwhile, I presume you trust your toaster with your life? Because that's made in China for as cheap as possible, and it's 120vac unshielded right next to where you stick your hand. So is a space heater. And a blow drier. And a light switch for that matter.

...

That said, for $42 including the Lipo that powers it... that ain't a bad deal. You're not going to be welding sheet metal with it, but for 18650s, you should be set.
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