Butters amt 241 value

[Pyrotechnic]

Hi all probably wrong section but I recently got a second hand esab c251 dirt cheap and was hoping to keep my butters amt 241 as well but after trying to re arrange the garage it's starting to get me down as to where to put them both.although I'm really not fond of the idea of selling the butters because it's a monster I might end up not having a choice :-(
So the question is if I do sell what's it worth in real time?
Comes with brand new 15kg esab wire and either a parker duragrip or parweld torch.
Now it's not actually for sale yet but it might be so need to know value.
It's got one hell of a duty cycle esp for single phase see photo.

 

[Jim Davey]

£300-400 I'd say. That's not actually a massive duty cycle (100A @ 100%) but on that kind of machine it's ample.

 

[Pyrotechnic]

I agree on the duty cycle but on the upper duty scale 200amps at 35% is better than my esab which suprised me

 

[windingroads]

Duty cycle alone does not tell the whole story, because it is based on amps produced,
and amps need to be compared to the voltage at which they are stated.
For example, 100 Amps at 10 Volts equates to 1Kw, (1000 Watts )
while ==== 100 Amps at 15 Volts equates to 1.5 Kw, which is half as much again,
So while both welder could read 100 Amps @ 100%, they are no where near the same
power output.
Oddly enough some manufacturers do not publish the volts their
welders produce, so as to hide their true output.

 

[windingroads]

While the electrical theory there is pretty sound, it doesn't apply directly with a mig.

The current in a mig is a product of the voltage and the resistance (wire diameter, arc length and feed speed).

This means that comparing '100A' between two machines is actually pretty accurate.

It applies to everything electrical, current produced is current produced, the wire is only the medium
that carries the current and has nothing to do with its creation, if it did there would be no way
to quantify the machines output without stating the wire used, its resistance etc, which is not the case.
If you change the voltage you change the amount of current required to melt the wire,
the wires resistance is over come by both these properties.

 

[windingroads]

You need all 3 to make a triangle, without vir you can't have piv.

Just because the wire melts you cannot disregard the resistance.

The simple fact is that - given the same wire, fed at the same speed with the tip at the same distance from the work - any two mig welding machines have to produce the same voltage to provide the necessary current.

It's electrically impossible for one mig to have 10V@100A and another to have 15V@100A without changing at least one of the parameters concerning resistance.

I agree on most of this, but we both know that changing the voltage will effect the amperage, look at a few different migs and one
will go up to say 29 volts at its peak of say 300 amps, then another will go to 32 volts at the same amps. The voltage comes from taps on the transformer.
It is these combinations of voltage and amps drawn that give each welder its basic characteristics, controlling the voltage and current is another factor which varies greatly between welders.

 

[windingroads]

I agree with this, but changing voltage does alter the amperage one draws to complete a task.
I agree too that there is or certainly should be parameters governing the testing
and rating of migs, and if the manufacturers do not adhere to these then we as
consumers do not really know what we are getting, thus I have always seen adequate
differences between two welders of the same amperages.
I will test some of this out if I get time, as I plan to hook up a Variable DC power supply to the
inductor of a mig, and do some testing to see how voltages alter amps drawn.
I can see no real problems with these tests, and if the welder performs as well as it
did from its own rectified DC, I will eliminate the control card and test the wlder once
again, note my findings, and try to design a circuit to over come the down falls
experienced.
Oddly enough i was thinking of posting about this subject just today, to see if anyone
had any experience of building their own mig welder.
The majority of the components should be cheap enough, but getting a control card
to manage it all will probably not be too easy, designing for a generic card would be a
nice feat, generic in that one card could control from 200 to 400 amp welders.

 

[windingroads]

I wonder too do they just measure the current drawn when welding at the transformer or inductor,
ie, the 30 volts or what ever it is. or do they measure the current going down the torch, one would think it
would be the current at the torch, I guess we are talking input versus output depending on what side of what
they measure.

 

[matt1978]

There are European norms relating to this issue and unfortunately machines at the lower end of the price scale don't tend to adhere to them.

The EU norm states how much voltage should be used against the amperage, the tests are usually done on a load bank in a climatic chamber so the wire diameter is not a issue as the machines are only "virtual" welding during the tests all measurements for Voltage and Current will be done at the load bank.

For example you see some machines marketed as a 250 amp machine, but the Transformer inside the machine isn't caperble of actually producing enough voltage to burn sufficient wire off to successfully weld at 250 amps.

Also all tests according to the EU norm should be done at a ambient temperature of 40 degrees, if it's not stated on the data plate then you can assume that it's more likely to be 25 degrees or even as low as 15 degrees in some cases. So unfortunately comparing numbers on a data plate from one make to another can be a bit of a minefield

 

[Jim Davey]

Tech Arc sell a universal MIG PCB that you could use in your project.

 

[windingroads]

Tech Arc sell a universal MIG PCB that you could use in your project.

That is indeed a prospect, but they may not sell it unless one supplies proof of purchase for a unit that accepts
the card, or a serial number. I looked up some time ago and found a card that costed half the price of a new welder.

Either way, could someone tell me what the card actually does, it seems to me that on the cheaper migs it does nothing
other than hold a pot for wire speed adjustment, spot and stitch is also a little easier with a pcb and a bit of code.
One can accomplish opening the gas selonoid with a relay, tirger on the torch brings in the main coil,
capacitors if installed don't need a control card either.

Just curious as to how it all comes together and what the main function of the control card is, I do realize in the more expensive
and functional welders the card does so much more, but for the standard cheap migs, what does the card actually do.

 

[Jim Davey]

That is indeed a prospect, but they may not sell it unless one supplies proof of purchase for a unit that accepts
the card, or a serial number. I looked up some time ago and found a card that costed half the price of a new welder.

Either way, could someone tell me what the card actually does, it seems to me that on the cheaper migs it does nothing
other than hold a pot for wire speed adjustment, spot and stitch is also a little easier with a pcb and a bit of code.
One can accomplish opening the gas selonoid with a relay, tirger on the torch brings in the main coil,
capacitors if installed don't need a control card either.

Just curious as to how it all comes together and what the main function of the control card is, I do realize in the more expensive
and functional welders the card does so much more, but for the standard cheap migs, what does the card actually do.

I'll happily sell you one, and I don't need to know a thing about what you want to do with it. It's a spare part after all, designed to be retro fitted to machines with obsolete boards.

Universal MIG PCB 23-55v input, wire speed control, burn-back timer, normal and latched trigger mode, wire inch function.

Has 2 relay controlled outputs for the switching contactor and a solenoid.

175mm x 100mmx 35mm

£71.50 + £6.50 P&P + VAT. As a guide, you may get it cheaper if they'll sell it to you direct, but gives you an idea. Not too bad at all really.

There is a cheaper version without the latch function and a narrower operating voltage range for £55.00 + VAT.

 

[windingroads]

There are European norms relating to this issue and unfortunately machines at the lower end of the price scale don't tend to adhere to them.

The EU norm states how much voltage should be used against the amperage, the tests are usually done on a load bank in a climatic chamber so the wire diameter is not a issue as the machines are only "virtual" welding during the tests all measurements for Voltage and Current will be done at the load bank.

For example you see some machines marketed as a 250 amp machine, but the Transformer inside the machine isn't caperble of actually producing enough voltage to burn sufficient wire off to successfully weld at 250 amps.

Also all tests according to the EU norm should be done at a ambient temperature of 40 degrees, if it's not stated on the data plate then you can assume that it's more likely to be 25 degrees or even as low as 15 degrees in some cases. So unfortunately comparing numbers on a data plate from one make to another can be a bit of a minefield

I could not agree more, let alone two similar specced machines from different manufacturers,
I have often found two supposedly identical specced machines from the same manufacturer to
be very dissimilar in their ability's, and yes, never again will I buy a mig that does not show
the welding voltages along with the amps.

Regards, john

 

[windingroads]

I'll happily sell you one, and I don't need to know a thing about what you want to do with it. It's a spare part after all, designed to be retro fitted to machines with obsolete boards.

Universal MIG PCB 23-55v input, wire speed control, burn-back timer, normal and latched trigger mode, wire inch function.

Has 2 relay controlled outputs for the switching contactor and a solenoid.

175mm x 100mmx 35mm

£71.50 + £6.50 P&P + VAT. As a guide, you may get it cheaper if they'll sell it to you direct, but gives you an idea. Not too bad at all really.

There is a cheaper version without the latch function and a narrower operating voltage range for £55.00 + VAT.

Thanks for taking time to explain this, the first board you mention starts off at 23 volt and goes up to 55,
so lets say for example I isolate the wire feed, add a transformer to supply the board with the highest voltage the
wire feeder expects to get, will this board then turn up and down this supplied voltage and feed it to the wire feed motor.
I ask as I have a welder, that actually seems to change speed, I can both hear the motor slowing and the welder changing
from spray to dip when the welding surface changes ever so slightly, it is as if the more amps drawn by the welding torch
the more the motor slows down, I can even hear the fans do the same, what this tells me is all these functions are drawing
their feed from the one transformer, this is nothing short of primitive and very dysfunctional.

 

[Jim Davey]

Yes, if you have a 42 volt motor I'd supply the board with 42 volts. You may need an auxiliary transformer with multiple tappings, as contactors, gas valves, motors and fans often run on different voltages. As for your fluctuating output, it sounds more like your supply cable/wiring isn't up to the task of supplying the machine what it needs.

 

[windingroads]

Yes, if you have a 42 volt motor I'd supply the board with 42 volts. You may need anauxiliary transformer with multiple tappings, as contactors, gas valves, motors and fans often run on different voltages. As for your fluctuating output, it sounds more like your supply cable/wiring isn't up to the task of supplying the machine what it needs.

Thanks for explaining, I really hope to get the time to look into this as I would love to put together my own welder, am on the lookout for one that has some faults so that I can just replace the problematic parts, test all as I go, if all is successful I will have at least more knowledge to move in the direction of building a mig from scratch.
Regarding the voltage, I can run any number of larger welders and they all function correctly, even two at the same time, and I use the same
outlet to ensure I have no such problem, I also meter the mains input so I can detect any such dips, and move over to generator power if need be.

Regards, john