# spot welding



## SE18 (Jan 20, 2014)

Hi, I completed a spot welder having watched this guy do it

http://www.youtube.com/watch?v=vrlvqib94xQ


Here's a vid I took of mine this morning

http://www.youtube.com/watch?v=hQjes1NHkkA&feature=youtu.be

Here are 2 questions

1. So it worked pretty well the first couple times. Then, oxidation formed on the 4 ga copper that does the spot welding and it wouldn't weld until I cleaned the now-darkish copper. Is this normal?

my leads coming out the transformer are 2 gauge. I basically did it the same as the dude in the first video so I won't re-explain how it's done

2. Also, I believe this is the only form of welding where dark goggles are not needed? I wear safety glasses as precaution


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## rangerman (Jan 20, 2014)

> Then, oxidation formed on the 4 ga copper that does the spot welding and  it wouldn't weld until I cleaned the now-darkish copper. Is this  normal?



Yes, that is normal for the type of electrode you are using. You are just using basically a scrap metal not specially designed for what it is doing.

The ideal is to use electrodes that would not easily oxidize when subjected to high heat. That's what most high quality commercial electrodes for spot welding employ. 
I don't really know the exact formulation used by commercial suppliers but it must contain special alloying metals to increase high-temp strength and minimize oxidation during use while still maintaining good electrical conductivity.

Since you are not in a commercial production mode your best remedy for the type of electrode that you are using is to just clean the tip frequently or periodically replace it with a new one every time you encounter problems with it.


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## SE18 (Jan 20, 2014)

thanks, interesting! But not just the tip, the copper holder too (electrical) oxidizes. That's a lot harder to clean

one interesting observation is that the transformer coils I wound don't touch each other physically but electricity passes thru and pumps out high amps at the electrode. If you're crazy enough to touch the electrodes, you'll find them hot but you won't get a shock (ask me why I know?) and I found that to be mysterious


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## rangerman (Jan 20, 2014)

Yes, that's how transformers fundamentally work. They work by electromagnetic induction principles. 
No direct or physical current path between the primary and secondary coils.


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## John Hasler (Jan 20, 2014)

SE18 said:


> Hi, I completed a spot welder having watched this guy do it
> 
> http://www.youtube.com/watch?v=vrlvqib94xQ
> 
> ...



You'll get better results and longer electrode life if you increase the clamping pressure.  You'd like to get a gas-tight seal.  

You don't need dark goggles.

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SE18 said:


> thanks, interesting! But not just the tip, the copper holder too (electrical) oxidizes.



Then you don't have an adequate connection.  That needs to be a high area, high pressure, gas tight connection.  You need a BIG honkin compression connector.  The point of contact between the pieces of steel to be welded must be the highest resistance in the circuit for the thing to work right, and that is a small fraction of an ohm.


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## jpfabricator (Jan 20, 2014)

Try using mig welding tips for your electrodes.
They may be better suited for the job

Sent from my H866C using Tapatalk 2


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## SE18 (Jan 21, 2014)

thanks for the VERY useful tips. Just advise I was looking for You rock!

BTW, I'm thinking that by substituting carbon arc rods I can also turn the spot welder into a resistanc soldering station.


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## SE18 (Jan 23, 2014)

one more question, are spot welders used to repair broken bandsaw blades (ones that cleanly snapped)? Or is it best just to throw them out and get new ones


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## John Hasler (Jan 23, 2014)

SE18 said:


> one more question, are spot welders used to repair broken bandsaw blades (ones that cleanly snapped)? Or is it best just to throw them out and get new ones



Spot welding is used to make them.  Fancy bandsaws come with built-in spot welders.  It requires a butt weld, though.  You grind the ends square, force them together in a fixture, and run current through the joint.

You can also braze them with silver solder.  I've done so successfully.  In that case you grind the ends to make a lap joint.


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## SE18 (Jan 23, 2014)

thanks!


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## SE18 (Feb 11, 2014)

I added a handle and foot pedal to my spot welder and mistakenly put the photos in "spotwelding aluminum" post, which is close to this post.

I did, btw, add new lugs and tighten things up and the spot welding is going seamlessly now


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## Walltoddj (Feb 11, 2014)

John Hasler said:


> Spot welding is used to make them.  Fancy bandsaws come with built-in spot welders.  It requires a butt weld, though.  You grind the ends square, force them together in a fixture, and run current through the joint.
> 
> You can also braze them with silver solder.  I've done so successfully.  In that case you grind the ends to make a lap joint.



Yes they are welded but not spot welded there are no welding tips the blade is melted together to form a weld. You do the same with an arc welder with a timer. I'm sure if you could find a way to set it up you could use a spot welder.

Todd


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