a couple of questions

[scarecrow]

i think this is my first tread in the mig section
I was doing a bit of practice today on some 2.5mm box with 1mm wire I can get it to weld okay but is always sounded a little poppy if you know what I mean so I thought maybe the wire was a bit heavy for the lower setting so i was just wondering is there a minimum current for a wire size
it sounded much better when you turned the welder up on heavier steel

when it was welding okay i changed the shroud back two the original one that came with the welder which is a good bit shorter than the new one because i cut off the burnt end and now is level with the tip
when I used this shroud is blew through and under cut on the same setting
so I'm wondering why the shroud makes such a difference to the power of a welder

 

[shenion]

If the shroud is shorter, then you were probably holding the torch tip closer to the work. The shorter the wire extends from the tip, the higher the current.

 

[scarecrow]

thanks shenion and that makes sense
could be a handy trick for anybody wait a small mig and needing to want something a little too heavy

 

[Sparkey]

You should be careful with that tho....it's best to have the tip a bit smaller then the shroud scarecrow!
I once managed to weld the whole lot together...tip, shroud...bungle...even the swan neck!
Bzzzzzt...splut....then nothing!
Made my way into the maintenance office...unseen....than pay a lot of coffee to a maintenance lad to sort your little problem out!!

 

[BillJ]

1mm wire sounds pretty large for welding 2.5mm thickness. As you say, perhaps it can't weld smoothly at the power setting you were using and there must certainly be a lower power limit for a given thickness of wire. I'd expect it needs a fair amount of power to melt 1mm wire and that you were into a mode of slow, repeated short-arcing.

What machine were you using?

 

[scarecrow]

You should be careful with that tho....it's best to have the tip a bit smaller then the shroud scarecrow!
I once managed to weld the whole lot together...tip, shroud...bungle...even the swan neck!
Bzzzzzt...splut....then nothing!
Made my way into the maintenance office...unseen....than pay a lot of coffee to a maintenance lad to sort your little problem out!!

female welders

1mm wire sounds pretty large for welding 2.5mm thickness. As you say, perhaps it can't weld smoothly at the power setting you were using and there must certainly be a lower power limit for a given thickness of wire. I'd expect it needs a fair amount of power to melt 1mm wire and that you were into a mode of slow, repeated short-arcing.

What machine were you using?

its a murex 251 tradesmig it welds lovely when you turn up the machine especially if you have it on the higher ocv setting. ill pick up a roll of .8mm this week and let you know how I get on

 

[Sparkey]

female welders

 

[Robotstar5]

than pay a lot of coffee to a maintenance lad to sort your little problem out!!

Maintenance saves the day again!

 

[Sparkey]

Maintenance saves the day again!

Is it a bird? nooo! Is it a plane? nooo! It's Super Maintenance Guy!!!!!!!

 

[scarecrow]

Is it a bird? nooo! Is it a plane? nooo! It's Super Maintenance Guy!!!!!!!

i wish I had a maintenance and guy or even better a gal probably won't be long til i need need one

just checking to see if I have this right my mig is 250 amp which has a minimum of 40 amp I think the power selector is marked 1 to 6 so it goes up in roughly 40 amps per number
the voltage selector has to setting which I presume are are low and high
the low is for short-circuit transfer and the high is for spray ark transfer

so I presume the amps are the same for both as the miller calculator uses amps and inches per minute for the wire feed which is easy enough to figure out

 

[shenion]

Power selector and voltage selector would be the same. Sounds more like a coarse and fine voltage setting.

 

[scarecrow]

Power selector and voltage selector would be the same. Sounds more like a coarse and fine voltage setting.

I know that the main power selector turns up the voltage but it must also turned up the amps looking at the Miller calculator it gives the power rating in amps so if i divide 250 by 6 (the amount of power settings) I get an increase of about 41 amps per setting
I'm not sure what course and fine voltage means i presume it's just more or less voltage at the different settings

here is a pick of the front of the machine

 

[shenion]

The two dials on the bottom are the voltage.

As seen by the icons underneath with the "stairs". The left is large steps, the right is small steps. So, you have 12 settings, left-1 and right 1-6 then left-2 and right 1-6.

They are not current but voltage. On any given setting the current is determined by the wire size and speed. If you use 0.6mm wire or 1.6mm wire, the current would be drastically different on a given setting.

 

[scarecrow]

is there any way to know the amps on different settings

 

[shenion]

is there any way to know the amps on different settings

You would rather know the voltage at each setting.

Using the miller calculator will show the voltage needed for a given weld size and wire size.

A rough estimate would be the weld settings calulator on the site.

Or you could guess by using a rough calculation of 250A-40A=210A. With 12 steps, that is 17.5A per setting. So coarse=1 and fine=1 is 40A, each step on fine adds 17.5A.

Again, on a given setting, switching from 0.6 or 0.8mm wire will double the current for the same setting.

The only accurate way would be to measure the RMS DC voltage an each setting under a load and correlate it to settings from something like the miller calculator.

My MIG has infinite settings. I just make a note what setting on 0.8mm wire works well on 3mm steel.

If you have a manual for the machine, it may specify the voltage range.

 

[scarecrow]

if I knew the voltage or the amps it would be great
the voltage range I think it is 19 to 37 thats the ocv on the manual
so I have 12 power settings one to six on the main power switch when the one on the left is on 1 and six to twelve when its on 2
so that would roughly mean that each setting increases the voltage by 1.5 v

only looking for rough setting so that ill have an idea where to start when welding heavier steel

 

[shenion]

You can use the 1.5V per setting. The OCV is close on bigger machines than low end ones (low-end machines have larger voltage drop when welding.)

Use the Miller Calculator to get a guess but it has limitations on it only gives a few wire sizes.

For example: 1/8 steel shows 18-19V on 0.9 and 1.1mm wire. Would probably be 21V on 0.8mm wire.

Mine has a volt meter but you need to look at it while welding, it is way higher with no load (OCV.)

Really, best is to just try it on a few thicknesses. On my Clarke I had a hand-written table of settings. Like power 2, 0.030 wire, wire speed 4 for 1/16" steel; power 4, 0.035 wire, wire speed 5 on 1/8" steel. Then I could guess easily the ones in between.

Try the weld setting calculator Malcom did (I linked to in last post.) Shoud give you a starting point.

 

[scarecrow]

i will probably use Malcolm's more than the Miller one as i can print it off and overtime I can right in a sort of coed of what settings and wire speed for different materials
i allways thought it was a bit funny having a volt meter on the machine when it didn't tell you anything until you started welding now if your had an LCD in your helmet it would make more sense

thanks shenion