Small Welder for Joining Nichrome and Nickel Wires




Introduction: 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.

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Step 1: Parts List

Here are the parts I am using (with digikey part #'s), feel free to substitute your own equivalents:

Batter Holder:  BH-18650-W-ND
Project Box:  377-1165-ND
Momentary Switch:  507PB-ND
Resistor:  3.6W-10-ND
Fuse:  507-1032-ND
LM2577 Board:   Ebay
Diode:  1N914B-ND
Capacitor:  399-6556-ND
Smooth Jaw Alligator clips:  314-1018-ND


Battery: 3.7v or any 3.5v-40v power source can be used
Strain Reliefs
Super Glue and Hot Melt Glue
Shrink wrap or electrical tape
22 Gauge stranded wire, 18 Gauge stranded wire
Solder, flux and Soldering Iron
Two small wire nuts

Step 2: Wire LM2577 and Put in Place

The board has solder pads on the top, for all connections, bring the leads from the back of the board and solder to the pad.  Some boards have IN/OUT and +/- marked on the back of the board, some do not.  If yours does not then mark them with a sharpie.  This will help when you are making the final connections a little later.

Solder the resistor to the IN +
Solder a 6" wire to the IN -
Solder the diode (note polarity, black ring faces away from board) to the OUT +
Solder a 6" wire to the OUT -

Line up the LM2577 board to the box and locate where the potentiometer screw is going to be, mark and drill 3/16" hole.
Apply superglue to the 2 capacitor tops on the board and glue in place.

Step 3: Drill Box and Attach Components

Solder alligator clips to 18" wire leads and run the wires through the strain reliefs.
Drill box for strain reliefs and insert.
Drill a hole for the momentary switch and secure switch to box.
Use hot melt glue to attach battery holder to outside of box, drill 2 small holes so the wire can be routed to inside of the box.
Add a dab of hot melt glue on the inside of the box where the battery holder wires come through to hold them in place.
Put hot melt glue on capacitor and glue to box with leads facing up.

Step 4: Complete the Wiring

Take + wire from battery holder and connect to one lead of switch.
Wire the other lead from switch to fuse with a wire nut (this makes the fuse easily replaceable).
Connect other end of fuse to resistor with another wire nut.

Connect diode and one alligator clip wire lead to + of capacitor (the longer lead is the +)

Connect both - wires from LM2577 the - from the battery and the other alligator clip wire lead to the - of the capacitor (the - is the short lead marked with the black strip running down the cap).

Step 5: Testing and Finishing Up

With all the wiring complete you can now test and verify everything is working as it should and adjust the voltage of the board using the potentiometer.

Hook the alligator clips to your multimeter and push the momentary button, you should see the voltage go up a little and stay steady around 12-14v which is where the boards are set when you get them. 

Using a small screwdriver start turning the potentiometer while holding the switch down.  If the voltage is not going up, you are turning it the wrong way.  Keep holding the button and turning the screw until you get to 35v.

You should have about 0.6 joules of energy stored in the capacitor.  Touch the wire leads together and they will short, cause a spark (intended action) and the meter will now read 0v.  If everything checks out, then you can add heat shrink or tape to all the exposed connections and screw the box together.  If not, double check all your connections.

Step 6: Welding Tips

Make sure you have a good connection on the clamps, periodic sanding with 400 grit paper may be needed.
Be sure to keep the ends of the wire as close to the clips as possible.
If your wire has a coating on it, lightly sand the tips to be welded.
Rather than trying to push the ends of the wire together, try to overlap the ends by 1mm for a strong joint.

If you have question or need some help troubleshooting your welder, the best place to get answers is here:

Big thanks to everyone on that forum who helped contribute to this project!

1 Person Made This Project!


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14 Discussions


4 years ago

Hello my friend, thanks for share. Just a question, your project can join a litler piece of iron-niquel, like used to make a battery pack to 18650 for exemple? Thanks for your attetion.


5 years ago on Introduction

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.


Reply 5 years ago on Introduction

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


6 years ago on Introduction

Thanks, built mine up last night, works like a charm.


6 years ago

Can't wait to try this!


6 years ago on Introduction

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?


6 years ago on Introduction

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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6 years ago on Introduction

What size Strain Reliefs are you using? And is the 22g wire you used for the aligator clips separated speaker wire?


6 years ago on Introduction

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


6 years ago on Introduction

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.