Murex Tradesmig 251

[Welderpaul]

ey up.

What is the lowest amperage my Murex Tradesmig 251 will go down to? and what is the thinest section steel it will weld? Instruction manual long disapeared under inches of grime int workshop!
I seem to be blowing holes in 2.5mm wall box. Don't know how you boys get on welding thin stuff on cars! - I am afraid, tasked with fixing car panels, it would be an overlap joint and a nice line of pop rivets! But thats why i'm not allowed near cars!

 

[Drains]

What gauge wire?

 

[Welderpaul]

0.8mm in it at the moment

 

[weldequip]

40amps.
weldequip

 

[Welderpaul]

hmmm whats thinnest it will weld at 40A? (I am a mma man mesel - is it a straight comparison 40a mig = 40a mma?)

 

[weldequip]

You will struggle on anything below 1.5-2mm, although if you put it on 0.6mm wire (will probably need another feed roller) it will make a huge difference.
weldequip

 

[Drains]

Different OCV. Yer migs more likely to be between 20 and 30. MMA 50+, so different power.

What I don't understand, and somebody please explain - is, that Mig is a constant voltage thing, right? So settings are voltage settings, not amps (see Lorenzos posts - no mention of amps there) MMA is constant current. Set the machine to 100A, that's what your getting.
So my point is that although your 250A machine only goes down as low as 40A, surely that's a sort of theoretical thing, depending on the wire stickout length etc, as the only constant is the voltage......
Help me somebody.....

BTW, you should be able to weld 20g on that machine. I could. Then again, I'm a crap stick welder, so there you go.

Aargh. Weldequips about to call me a bullshitter!
Oh no, it's ok, he hasn't. Phew

 

[weldequip]

The thinnest rod available for an MMA (stick) set is 1.6mm, whereas the thinnest wire available for a MIG is 0.6mm. Now it don't take much science (& I don't know the exact science in it) but 0.6mm wire requires less current to melt it than 1.6mm does.
weldequip

 

[Welderpaul]

You will struggle on anything below 1.5-2mm, although if you put it on 0.6mm wire (will probably need another feed roller) it will make a huge difference.
weldequip

I need to give it a go, i've got to change a habit of a lifetime and go the mig way! Weldequip can you quote me happy for a few 0.6mm tips for a MB25 and if yer can, a feed roller (don't think the one thats in will do 0.6, and if you do it, a 15kg spool of 0.6 mild wire?
Cheers for the liners old bean!

 

[Drains]

The thinnest rod available for an MMA (stick) set is 1.6mm, whereas the thinnest wire available for a MIG is 0.6mm. Now it don't take much science (& I don't know the exact science in it) but 0.6mm wire requires less current to melt it than 1.6mm does.
weldequip

So doesn't that mean that if your machine only goes down to 40A, if you use a thicker wire, it'll take more amps to melt, so less likely to blow holes?

Hmm

 

[Welderpaul]

Different OCV. Yer migs more likely to be between 20 and 30. MMA 50+, so different power.

What I don't understand, and somebody please explain - is, that Mig is a constant voltage thing, right? So settings are voltage settings, not amps (see Lorenzos posts - no mention of amps there) MMA is constant current. Set the machine to 100A, that's what your getting.
So my point is that although your 250A machine only goes down as low as 40A, surely that's a sort of theoretical thing, depending on the wire stickout length etc, as the only constant is the voltage......
Help me somebody.....

BTW, you should be able to weld 20g on that machine. I could. Then again, I'm a crap stick welder, so there you go.

Aargh. Weldequips about to call me a bullshitter!
Oh no, it's ok, he hasn't. Phew

Hmmm I feel a weld-off coming on here Drainsy! If I couple enough leads together i should just about reach your neck of the woods with me electrode holder.

 

[Drains]

Lol. How thin can you go?

 

[Welderpaul]

1.5 mm on mma. owt else gets mechanically fixed!

 

[weldequip]

So doesn't that mean that if your machine only goes down to 40A, if you use a thicker wire, it'll take more amps to melt, so less likely to blow holes?

Hmm

Err... well yes, but if you don't have enough amps to fuse the two metals together correctly, you don't have a sound weld.
The Tradesmig 251 is a fabrication machine & not designed for thin sheet welding, period.
weldequip

 

[Weldingartisan]

Weldequip
I beg to differ. Whilst heavy duty mma machines become unstable at low current therefore difficult to use on thin material, the opposite happens on large mig machines which give a more stable voltage at low settings. Hence I can weld thinner material on my Eland 320 with 0.8 wire than I can with a Transmig 110 on 0.6 wire. W/A

 

[weldequip]

Transmig 110, that's pre-war!! Things have moved on a little. The Tradesmig 251 is designed for fabrication work & goes down to 40amps. The newly released Tradesmig 140 only has 5amps less minimum setting at 35amps BUT has a lower OCV so is able to weld thinner material.
weldequip

 

[Weldingartisan]

The age of the machine is not the point, voltage is regulated on mig machines and is far more stable on larger machines, where on a WPS is the current ever mentioned for the mig/mag process? OCV is important on mma machines as many electrodes have a minimum requirement, but the current is regulated for welding power. I also have a Kemppi 180 adaptive mig, which is modern technology but no better than the Eland (actually Murex power unit) at low voltage/wire speed.

 

[Drains]

The age of the machine is not the point, voltage is regulated on mig machines and is far more stable on larger machines, where on a WPS is the current ever mentioned for the mig/mag process? OCV is important on mma machines as many electrodes have a minimum requirement, but the current is regulated for welding power. I also have a Kemppi 180 adaptive mig, which is modern technology but no better than the Eland (actually Murex power unit) at low voltage/wire speed.

So, weldingartisan, can you or (anybody else) explain the relevance, if any, of minimum current output on a MIG set? As you say, a WPS has a voltage only and that as we know is because a MIG is a constant voltage machine. So presumably the current can be below spec (eg 40A on a 251 Tradesmig...)

I know I can weld 1mm sheet with a 300A Lincoln running 1mm wire... just. I mean, i'm pushing it, and thats a tight fitted joint, but it can be done. 16 settings though. How many does a 251 have?

 

[Welderpaul]

Murex Tradesmig 251 has 2 coarse settings and 6 fine. er...... 12 settings then!

 

[Welderpaul]

Just noticed today feed roller wrong fer the wire (0.8). Its a 0.6 and 0.8 roller. Put in the wrong way round. still worked tho!