Picture of Small Welder for joining Nichrome and Nickel Wires
How to build a small arc welder for joining resistance and no resistance wires together.  28 gauge single strand through 34 gauge single strand wires are optimal for this design.  Designed to run off a single 3.7v battery.

There are a lot of possible variations on this, I chose to keep the battery outside the box so I could pop it in and out rather than use a separate on/off switch.  Another capacitor or a larger one can be substituted and voltage set lower to increase total joules potential but I have found 1000uf at 35v to be just right for welding silver, nickel, nichrome and kanthal 28-34g wires together.  Really any old power supply can be substituted for the battery as long as it is within limits of the input voltage for the LM2577 board, I just have 18650 lithium ion batteries always charged and on my nightstand so it is convenient for me to use this form factor.

The cost for the components is right around $25.  You can buy bulk wire for about $25 for 250 feet.  Commercially available resistance/no resistance wires are available for $1ea and measure 3" long.  So with the same $50 investment and a few hours of your time you can make 1000 wires for what it would cost you to buy the pre made ones.   Plus, by building your own, you have control over what wire gauge, what material, and what resistance the final wire will be.

This is not my original idea, nor is it the only way to make such a device.  This is simply a illustrated guide to build one the way I built mine.

fairmana1 year ago

As another person mentioned, I had a problem with the voltage dropping off after charging. I discovered that the diode that was included in the instructable failed soon after. I had bought 2 of them, but the replacement diode also failed after a short time. I don't think this diode is the best choice for this application (too high of a reverse voltage?). Anyway, I recommend replacing it with a 1N4001 diode instead. Works great now.

Sorry, meant to write 1N4004, not a 1N4001.

wshappley7496 made it!1 year ago

did something wrong seems to run backwards push button and jumps to 35 then slowly bleeds down? any help it works but have to be quick!

Lcstyle1 year ago
Thanks, built mine up last night, works like a charm.
myheaulon1 year ago
Can't wait to try this!
Atrophius1 year ago
I was curious if this could weld silver, copper or even stainless wire. I do metal crafts with wire anywhere from 18ga to 24ga wire and am looking for something to weld the wire. Do you think there is a way to scale this up a little for a thicker metal? or will just doing multiple welds work?
zpeedie1 year ago
Fantastic!  Worked like a charm!  I had a good portion of the misc supplies around the house, including a rubber grommet kit from Harbor Freight.  I've been able to successfully join a number of different types of wire, including non-resistance nickel and silver to 28-34 gague kanthal.  

I also mounted my battery holder inside the project box to make the device slightly more "portable".  I also chose not to drill a hole to provide access to the potentiometer since once you increase the voltage to 35V, you don't really have much need to access it again.  

I know some of the folks in the forum have been suggesting different components, but I built this exactly as it was originally presented.  I've done a couple of dozen joins, and haven't had a single hiccup.  

Oh, and you may want to be sure you have some small wire nuts on hand.  I managed to scrounge a few up in the garage, but I'm guessing most people won't have the right size.  

Thanks again for the great guide!!

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rnord1 year ago
What size Strain Reliefs are you using? And is the 22g wire you used for the aligator clips separated speaker wire?
this is just wot i needed for my 705 killer and my diver after building it though i found i needed more power to get a good weld but this is possable with a diffrent board thank you i have tryed to contact you gsa but im computer dumb cmac
lburch12 years ago
Have you tried welding regular wire to a LED lead? I need to find a faster way than soldering. I imagine you would need more joules because you don’t have the high resistance of the Nichrome wire.
idn.affan2 years ago
Now I get it ! Thanks for sharing and VAPE ON ! ! !
SpeakerBoy2 years ago
Now that's right handy! Thanks! And oh, Vape On, Brother!
Awesome. Thanks for the share.