Diode upgrade in welder

michael8

Joined Jan 11, 2015
243
I heard that you could get a much better sizzle and control of heat especially when welding with thin gauge sheet metal. For instance I notice the much higher end machines like Millers seem to have a better crisp sizzle,

see: https://www.jasic.co.uk/post/what-is-inductance-in-mig-mag-welding

You'd need an inductor which could carry the full welding current without saturating. This could
be outside the welder so not as much of a space problem.
 

shortbus

Joined Sep 30, 2009
9,066
You'd need an inductor which could carry the full welding current without saturating. This could
be outside the welder so not as much of a space problem.
You hit the reason the more expensive Migs are better. Bigger or even just the fact there is a choke/inductor in the circuit.
 

sparky 1

Joined Nov 3, 2018
652
The balance between wire speed and voltage is tuned to where the operator prefers.
On sheet metal a transformer's weld time which is related to temperature is better than
heavy metal. The stud diodes are actually rectifier diodes that cause unidirectional flow when the arc is established
the molten metal particles deposit uniformly, when the welder is adjusted it is said to sizzle.
In electronics when something sizzles we were only smoke testing.
The surface must be clean from scale and rust. To improve the performance the duty cycle is the first concideration.
https://www.weldclass.com.au/blog/43-welding-machines-what-is-duty-cycle-how-is-it-calculated-

Hotrod sheet metal welder not as pretty as tig, mig on sheetmetal is for just get er done and smooth it off.
 
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MisterBill2

Joined Jan 23, 2018
10,582
OK, from the easily read circuit drawing it shows that the welder already has an output choke. If there is room for a larger output choke inside the case, then you may be able to change to one with more inductance without altering the portability of your welder, except for making it heavier.
The inductance of that output choke depends on both the number of turns and on the amount of iron in the core. The other important thing is the conductor resistance, determined mostly by the wire diameter. It might even be possible to add more turns to the present choke, but if that would help is unknown, it might not be enough improvement to be worth the effort.
It might possibly be a benefit to replace the present rectifiers with some rated for both more current capacity and a lower voltage drop, but there again the amount of benefit is unknown. Measuring the full-load voltage drop of your present diodes will tell you if they are all functioning as intended and how much you might gain.
also, checking the connections of that capacitor, "C1" to make sure they are solid will be useful. I am thinking that capacitor is fairly important to the best operation. IF it is supposed to resonate with the output choke, it might be very important.
 

shortbus

Joined Sep 30, 2009
9,066
As someone who actually went took a short course on Mig welding, to become a better welder, this talk or "sizzle" is funny to me. I thought the same thing before being schooled. Every one that's self taught on Mig is under the same idea, point the gun and pull the trigger and if you don't get a good weld it's the machines fault.
That can be the problem but I learned that most times the sizzle your talking about has more to due with distance from the weld gun to the work than anything else. The biggest problem that most people have is keeping too much distance from the gun electrode, the little copper looking tube the wire comes out of, and the work. To much distance causes the wire to melt outside of the weld bead and causes more spatter and less of the Sizzle. Also too much gas pressure or flow is bad to the weld health.
 

Papabravo

Joined Feb 24, 2006
17,616
What numerous "modders" seem to forget is the law of unintended consequences. When you have little to no idea why you are doing something, the results can be a great del less than you expect, with little to no possibility of reversing the results. Getting to the root cause of a problem is often the most effective strategy.
 

MisterBill2

Joined Jan 23, 2018
10,582
After realizing the capacitance of the C1 capacitor, my advice about checking the integrity of the connections still holds. It is there to assure a rather solid DC power for a smooth weld.
 
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