I agree it’s dangerous …but a momentary switch can resolve the issue of the contacts welding accidentally to the piece you are welding
The arduino spot welder has a foot switch. I am pretty confident that stops one of the electrodes welding unless you push the switch.
you would have to use a relay, but yea that would increase the safety factor by a lot.
Oh and running a long line away from the battery lol like outside lol
I’m ordering all the parts needed for an arduino spot welder. Once I’m done, I can post a mouser order list and update once I build it. Going to be welding a 10S4P battery for my new board. I ordered the PCB’s through Bay Area Circuits.
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Hi,
I have 8 packs of:
- PCB
- Foot switch
- Arduino to build this: http://www.instructables.com/id/DIY-Arduino-Battery-Spot-Welder/?ALLSTEPS
PCB printed by PCBWay, latest design (13Jun2016), single piece to be cut. Foot switch from kEK, 10 x 6 x 3.5 cm. Arduino Nano v3 (ATMEGA328P-AU, CH340) in antistatic bag.
13 EUR + shipping from .HU
Let me know if you are interested!
R, J.
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Hi @Tarzan,
I checked but:
- cable and battery terminal set are heavy, more than 2x heavier than the 3 components. In local stores they are cheaper plus you have to select the terminal based on the car battery you use.
- electronic components can be easily ordered in 1 pack with 1 click from .DE - and the price is almost the best: https://secure.reichelt.de/index.html?&ACTION=20&AWKID=1203408&PROVID=2084
R, J.
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there is a reichelt shopping card link - just order it yourself and you are good. https://secure.reichelt.de/index.html?&ACTION=20&AWKID=1203408&PROVID=2084 (Ok you need to also buy cables and a car battery)
Edit: @kovjanos was 10 microseconds faster 
Your three parts + link from reichelt + (additionally) car battery = complete spotwelder? The terminal must match the battery. Which/What terminal? Does i am missing something?
you also need cables and electrodes. with the terminal I think he means something like this: https://www.hornbach.de/shop/Presskabelschuh-16-x-10-5/4046168/artikel.html which is for the connection to the battery
Hi @DeathCookies,
You will also need:
- some cables - thin for powering the board and connecting the foot switch and thick for welding.
- something to mount the thick cable to the battery, e.g. terminal set
E.g. 1m of 1G10 cable plus a pair of small terminal set that fits on my battery.
R, J.
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What did you use for electrodes?
I think they usually just use a piece of 10mm² solid copper wire and remove the insulation.
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Similar size but solid copper wire.
Just find a friendly guy in the shop and agree to pay extra 20cm of the welding wire but have the 20cm from the solid wire. This is good if minimal length to buy would be 1m… If you are lucky you will get it for free 
R, J.
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Awesome guys!
I ordered the parts from reichelt.de now I need your three parts.
Shipping to Germany is okay I hope
PM me your Paypal and you have a customer.
Lets buy together to save some shipping costs? i believe you live in hagen? I am from muenster so we could arrange something?
If we save some € of course!
Unfortunately I have ordered the parts from Reichelt 4 min ago. 5,50 € Shipping 
Can’t you cancel the order? Shouldn’t be a problem so close to the time of order.
@DeathCookies and @Tarzan: should I pack 2 sets of the 3 components into one box? That would really save some EUR for you if you chose DPD or GLS but as a standard post parcel it would save only ~2EUR (~8 instead of 2x ~5) as one pack is ~160g and the limit is 250g but the two packs would fit only into the 500g limit…
R, J.