AC Vs. DC Spot Welding Wire Gauge

[rg12]

I noticed that the kWeld which is very powerful (can do 0.2mm thick pure nickel) works with 30cm long 8AWG wires.
My AC spot welder has 30cm long 1AWG that are even shorter than that and I can't even do 0.2mm nickel.
If I connect 8AWG to my AC transformer I probably wouldn't be able to weld 0.1mm plated nickel.
What am I missing?

 

[spinningmagnets]

How many amps does your AC welder put out? and also, what voltage?

Is your AC welder a Sunkko? Which model?

 

[rg12]

How many amps does your AC welder put out? and also, what voltage?

Is your AC welder a Sunkko? Which model?

It's a chinese pneumatic, pretty basic that I modified to work on a table and have a long depth.
Originally it had 1AWG coming from the transformer to the probes but I extended it by about 20cm and it weakened the welds to useless so I now use 3/0AWG and it works great.

 

[thepronghorn]

The welding power is the current that you are able to put into the weld (assuming the weld time is the same).

From ohm's law, current = voltage / resistance. You are saying that with similar wire gauge (aka similar resistance), your DC kWeld is putting out more power than your AC spot welder. This is probably because the kWeld voltage is higher. What voltage battery do you have hooked up to your kWeld? Can you measure the voltage output of your AC spot welder without any load? That might give you some clues.

More turns around the transformer for the wire connected to the probes will give you more voltage which might give you more current even if you have to use smaller wire with higher resistance.

The other option might be that the transformer in the AC spot welder is saturating which is limiting power. Google "transformer saturation" for more info on this, but basically there is a limit to how much magnetic field the iron in the transformer can carry.

 

[rg12]

The welding power is the current that you are able to put into the weld (assuming the weld time is the same).

From ohm's law, current = voltage / resistance. You are saying that with similar wire gauge (aka similar resistance), your DC kWeld is putting out more power than your AC spot welder. This is probably because the kWeld voltage is higher. What voltage battery do you have hooked up to your kWeld? Can you measure the voltage output of your AC spot welder without any load? That might give you some clues.

More turns around the transformer for the wire connected to the probes will give you more voltage which might give you more current even if you have to use smaller wire with higher resistance.

The other option might be that the transformer in the AC spot welder is saturating which is limiting power. Google "transformer saturation" for more info on this, but basically there is a limit to how much magnetic field the iron in the transformer can carry.

I have the kWeld on the way, I just see on youtube people welding 0.2mm nickel with 8awg 30cm (pretty long) wires.
My AC welder has two turns, I was told it's about 2V

 

[fechter]

I have the kWeld on the way, I just see on youtube people welding 0.2mm nickel with 8awg 30cm (pretty long) wires.
My AC welder has two turns, I was told it's about 2V

The kWeld or similar is using about 12v for the source vs. 2v on your AC welder. This gives the kWeld a lot more head room for resistance losses in the cables. If you can rewind the AC welder with more turns it will help.

 

[rg12]

I have the kWeld on the way, I just see on youtube people welding 0.2mm nickel with 8awg 30cm (pretty long) wires.
My AC welder has two turns, I was told it's about 2V

The kWeld or similar is using about 12v for the source vs. 2v on your AC welder. This gives the kWeld a lot more head room for resistance losses in the cables. If you can rewind the AC welder with more turns it will help.

Oh wow, that means I can use a 6th of the thickness I'm using now which is exactly 8AWG nice

 

[fechter]

If you use too many turns you will start blowing things on the primary side as the power will be increasing. I can't say what optimum will be so you may need to do some tests before you make the final configuration.