120v MIG 3/8" coupon test results

[Blade Breaker]

Jim, it would be normal that you would think that. But that would not be the case. To get to the bottom of the matter, you must read the fine print.
Hobart (and Miller and Lincoln etc.) small MIGs give their input rating at their rated output. The rated output is usually the number that looks the most "appealing" for marketing purposes. If you look carefully it states amps input at rated output. Rated output is 90 amps @ 20% duty cycle. Yet, the company states maximum output is at 140 amps. That's a far cry from 90 amps and requires a lot more amps input. The other factor is the relatively new way they state input ratings and that the old way is still allowed. The "preferred" way is to state the I1Max and the I1EFF currents. I am not an electrician and my understanding may not be perfect or accurate in all respects. However, I do try to stay on top of these things. Many welding companies are still using the older way which can muddy the picture somewhat. The I1Max method allows you to properly size breaker, and then the wiring separately. The I1max accounts for the maximum inrush experienced at start up. The I1EFF is the rated effective current draw. Here's a link discussing this for welders:Page 70-537

There are some units we offer and other companies such as Miller offer with inrush ratings of 40 amps or more on 120V for maximum output. They do a good job disguising this, however. They 120V input rating for a Dynasty 200DX is 31 amps (stick operation) @ 100% duty cycle. The machine is rated for up to 200 amps on 120V! Then there is a disclaimer that the units are limited by duty cycle due to input cord sizing. That gets confusing for sure.

To sum it up, no input/output ratings have little to do with what someone might have. The numbers are manipulated by mfgr's in such a way that it makes a person see and think that 140 amps are certainly capable...but then in the fine print show 90 amps output at 20 amps input...and even less on 15 amps input around 70 -75 amps. People think 140, but have no idea they are playing around usually about half that.

Excellent job of explaining this!

 

[Sodo]

I've been running my 120v MIGs on 20A outlets, never pop breakers, machine has never shut down. I have no experience to offer running on a 15A circuit. Lots of projects won't require max power though.

A useful 15A question might be: With the machine set properly to weld 1/8" material, does it work OK on a 15A circuit?

 

[Mark @ Everlast]

As far as output amps...The general rule for welding with some exceptions is 1 amp per every .001"...regardless of 120V/240V ratings.

 

[MinnesotaDaveChalmers]

Jim, it would be normal that you would think that. But that would not be the case. To get to the bottom of the matter, you must read the fine print.
Hobart (and Miller and Lincoln etc.) small MIGs give their input rating at their rated output. The rated output is usually the number that looks the most "appealing" for marketing purposes. If you look carefully it states amps input at rated output. Rated output is 90 amps @ 20% duty cycle. Yet, the company states maximum output is at 140 amps. That's a far cry from 90 amps and requires a lot more amps input. The other factor is the relatively new way they state input ratings and that the old way is still allowed. The "preferred" way is to state the I1Max and the I1EFF currents. I am not an electrician and my understanding may not be perfect or accurate in all respects. However, I do try to stay on top of these things. Many welding companies are still using the older way which can muddy the picture somewhat. The I1Max method allows you to properly size breaker, and then the wiring separately. The I1max accounts for the maximum inrush experienced at start up. The I1EFF is the rated effective current draw. Here's a link discussing this for welders:Page 70-537

There are some units we offer and other companies such as Miller offer with inrush ratings of 40 amps or more on 120V for maximum output. They do a good job disguising this, however. They 120V input rating for a Dynasty 200DX is 31 amps (stick operation) @ 60% duty cycle which is only 100 amps output. The machine is rated for up to 200 amps on 120V! Then there is a disclaimer that the units are limited by duty cycle due to input cord sizing. That gets confusing for sure.

To sum it up, no input/output ratings have little to do with what someone might have. The numbers are manipulated by mfgr's in such a way that it makes a person see and think that 140 amps are certainly capable...but then in the fine print show 90 amps output at 20 amps input...and even less on 15 amps input around 70 -75 amps. People think 140, but have no idea they are playing around usually about half that.

Yep - I never liked the funny numbers used. Hides the concepts in play unless a person knows a little about what to expect.

Here's a good example of the millermatic 140 mig (but pretty typical for many others).

90 amps at 20% duty cycle - using 20amps 120v plug.
140 amps at 10% duty cycle (or less) - but the current required is not listed (1 min is almost zero minutes when it comes to welding anyway IMHO).

 

[IslandTractor]

I'm still confused over the output of autosensing dual voltage machines when running on 120V. Presumably these machines have more guts than the typical 120V welder as they can also weld at 220 and are typically used at 220 for welding above 3/16ths steel. Shouldn't they be able to utilize even more than 20 amps/120 if available. Don't generators often/typically have 30amp 120 service? Wouldn't a dual voltage machine running on the 30amp 120 circuit of a welder put out significantly more welding power?

 

[MinnesotaDaveChalmers]

I'm still confused over the output of autosensing dual voltage machines when running on 120V. Presumably these machines have more guts than the typical 120V welder as they can also weld at 220 and are typically used at 220 for welding above 3/16ths steel. Shouldn't they be able to utilize even more than 20 amps/120 if available. Don't generators often/typically have 30amp 120 service? Wouldn't a dual voltage machine running on the 30amp 120 circuit of a welder put out significantly more welding power?

My gut reaction says yes, it would put out more power - I've seen really old machines that were rated for 40 amps 120v input.

I can't see how it wouldn't work considering it's capable of outputting more juice if it gets enough input.

Just a guess though - if I owned one I'd definitely ask the manufacturer about it.

But, remember that a generator is limited in how much inrush current surge it can provide.

 

[IslandTractor]

On a related technical issue, if you were trying to weld 3/8" steel with 120V, wouldn't you get better penetration (and avoid Mark's outcome) if you preheated the steel? Again, I know this may not be practical but I'm wondering if in a setting where propane or oxyacetylene and 120V were available but 220V was not, whether preheating would help with the penetration issue Mark demonstrated.

 

[Sodo]

F

Just a guess though - if I owned one I'd definitely ask the manufacturer about it.
But, remember that a generator is limited in how much inrush current surge it can provide.

Yes Dave that's worth a call to Miller. Seems like it could autosense voltage, but how can it measure service amps capacity? Doesn't seem possible.

Island, here's my in-use experience. My paired 120v generators has a "30A service". The set can put out 120v 33A for a few minutes (and 26A continuous). In use (at 1/4" preset) when you pull the trigger, the generators "bog" a little (as the generator floors the throttle). This is the opposite of what it needs, and of may exacerbate a MIG's 'cold start' problem. I don't know if the inverter generator has any reserve capacity in holding, (or maybe an inverter welder has some) but by the way the welder is behaving, I doubt it's enough. Good luck translating that to your situation. Sorry it's all I have.

At the 3/16" preset running the MultiMatic on the paired Hondas works fine.

Furthermore, I asked Miller about welding with MultiMatic at 240v and they said their recommendation is 7200W continuous. I said "is 7200w the minimum?" And he said "that's the number we have in our specs but we hear good results from our customers using generators with a continuous rating of 7,000w and more." Incidentally I asked how "clean" the output of the generator has to be and they said the Multimatic can handle pretty much anything a generator puts out. They were pretty proud of the MultiMatic, said it was designed to handle any generator output.

======================

Getting back to the topic of welding "too-thick" material with a 120v MIG.

A large propane roofing/weedburner torch can work for preheat too, and a nice one costs about $20 at Harbor Freight. I've seen this same torch elsewhere under various no-name brandnames for $40/$50. I suspect in many cases preheating is more practical than re-wiring for 240v (or giving up).

I preheated 1/4" workpieces once, it was doable, but a hassle. And dangerous when your old habits are to weld a little, flip it over, keep welding. The WHOLE workpiece is HOT. I flipped the workpiece and it touched the gun and melted the plastic trigger, so things are 'different'. In later years, realized preheating (that one project) wasn't necessary but good for a little added experience.

 

[Mark @ Everlast]

Many units put limits on units with dual voltage. The Miller 211 puts out the same specs as the 140 on 120V.

A word about preheat. It was over 100 degrees in my shop to begin with. The first pass would have heated the metal up plenty, and the next 6 passes would have been plenty hot. I've got the burn on my hand where I was using too thin of gloves to prove it.

Many generators that have a 30 amp rating are actually two 15 amp circuits...

 

[ericher69]

Many units put limits on units with dual voltage. The Miller 211 puts out the same specs as the 140 on 120V. A word about preheat. It was over 100 degrees in my shop to begin with. The first pass would have heated the metal up plenty, and the next 6 passes would have been plenty hot. I've got the burn on my hand where I was using too thin of gloves to prove it. Many generators that have a 30 amp rating are actually two 15 amp circuits...

7 passes to weld 3/8"???

Really?

Thanks for taking the time to do this test!

Sent from my iPhone 5s 64Gb using TractorByNet