Understanding Multi Pass Weld Settings!

[Nick DV]

28V, 12.0m/min would be a good starting point

Thanks Brad, I'll give that a try

 

[Munkul]

Oxford say that max volts is 32V.

If it's 32v under full load I'd be very surprised... I bet it's closer to 28v at 240 amps. But i could be wrong. Some machines drop voltage more under load than others.

Like brad says, 28v and 12m/min wirespeed is a good starting point. If you can push that hard. On my old machine, 12m/min would give around 260 amps. I'd try it with your machine and see what it does. It won't have a hard limit of 240 amps anyway so it may well do it, if the voltage doesn't drop too far. Keep a fairly close contact tip to work distance (CTTWD)

I've got some measurements written down from my old Miller which had volts, wirespeed and average welding amps readouts. 10 m/min = 230 amps, give or take (depending on CTTWD)

 

[Nick DV]

If it's 32v under full load I'd be very surprised... I bet it's closer to 28v at 240 amps. But i could be wrong. Some machines drop voltage more under load than others.

I wanted to find out what the voltage range was for my machine as the handbook is pretty useless, so I asked @Tom Orrow L to find out from the lads that make the mig and they said the range was 16V - 32V. I didn't opt for the volt/amps read out on my machine so I can't really check.

What do you recommend as the CTTWD in this instance?

 

[Munkul]

What do you recommend as the CTTWD in this instance?

Close I can't really say tbh, I know what "feels" and looks right with an MB36 or bigger torch, but I'd say I'd struggle to gauge it properly with a smaller torch.

 

[Nick DV]

Close I can't really say tbh, I know what "feels" and looks right with an MB36 or bigger torch, but I'd say I'd struggle to gauge it properly with a smaller torch.

Fair enough, I guess I'll have a play and find out

 

[Robert Mullins]

... Which is incorrect. Its the extra wirespeed that gives you the penetration. The extra volts just wastes heat in arc length.
Sorry Robert, I know it works for you, but it's simply incorrect advice. It always has been, and always will be.

If you had read my original reply properly, you would have noted that I advised " as much wire as possible" this wire pushes the arc deeper into the weld pool: spray transfer occurs when the voltage is raised above 27v, the advice is not simply erroneous

 

[daleyd]

Its very simple Nick, assuming you are double beveling your stinger bead is the most important and needs to be sufficient to correctly fuse both pieces of metal together on one side then turn it over and weld into your bevel with enough power (turn it up if necessary) to weld and fuse both bevels on the opposite side and into the stinger bead on the other side, from there torch angle becomes more critical as you need to fuse the stinger beads into the sides of the bevel to make your multiple passes.

Do you mean “stringer”?

 

[Jack Ryan]

Do you mean “stringer”?

I find that terminology, particularly unofficial terminology, varies from place to place.

I believe . was referring to the root bead initially and then stringer beads for subsequent passes - assuming that subsequent passes were laid without weaving.

There was probably an unhelpful auto-correction.

Jack

 

[daleyd]

I find that terminology, particularly unofficial terminology, varies from place to place.

I believe . was referring to the root bead initially and then stringer beads for subsequent passes - assuming that subsequent passes were laid without weaving.

There was probably an unhelpful auto-correction.

Jack

That’s what a stringer is, but I’ve never heard it referred to as a “stinger” before. I had assumed that’s what he meant but wasn’t sure on the terminology.

 

[8ob]

Easiest way to do it is to make sure you're in spray transfer, you'll (generally) get plenty penetration that way I

Thats about it, I am not sure why folk get so hung up on "settings". Should be obvious through the lens whether you are getting penetration and what needs an immediate tweek on the settings.

Bob

 

[Jack Ryan]

That’s what a stringer is, but I’ve never heard it referred to as a “stinger” before. I had assumed that’s what he meant but wasn’t sure on the terminology.

I guess it was an unintended auto-correct. A Stinger (originally a product name) is slang for an electrode holder. Very common in some places.

Jack

 

[daleyd]

I guess it was an unintended auto-correct. A Stinger (originally a product name) is slang for an electrode holder. Very common in some places.

Jack

Yes I know what stinger refers to as well, though it’s probably not as commonly used over here. Maybe it was autocorrect, I have my own suspicions as to the cause but there you go, let’s not detract from the thread any longer .

 

[Nick DV]

If you had read my original reply properly, you would have noted that I advised " as much wire as possible" this wire pushes the arc deeper into the weld pool: spray transfer occurs when the voltage is raised above 27v, the advice is not simply erroneous

Thanks for your input Robert. It's interesting to see/hear how different welders weld, but nonetheless, it's all good for stimulating the little grey cells

Its very simple Nick, assuming you are double beveling your stinger bead is the most important and needs to be sufficient to correctly fuse both pieces of metal together on one side then turn it over and weld into your bevel with enough power (turn it up if necessary) to weld and fuse both bevels on the opposite side and into the stinger bead on the other side, from there torch angle becomes more critical as you need to fuse the stinger beads into the sides of the bevel to make your multiple passes.

Thanks MM, I understand. I was originally thinking of a single 'V' bevel. I'll have to have a go with a double - once I grab some more thick steel.

Thats about it, I am not sure why folk get so hung up on "settings". Should be obvious through the lens whether you are getting penetration and what needs an immediate tweek on the settings.

Bob

Thanks Bob. I take your point but I'm a pretty inexperienced welder and when I'm learning new stuff, I like to understand what's going on and why, as opposed to just ploughing on blindly and hoping things work out. If I know why/how something works, then I can eliminate most problems before they occur. I also appreciate everyone taking time to answer my silly questions

 

[Nick DV]

You're welcome Nick, a single bevel creates heat distortion and a double bevel equalises this by pulling in the opposite direction and your work remains flat, think of it as a halfway house to sequence welding, but simpler and done at home.

Thanks mate, and 'simpler' is always good

 

[Ed.]

One thing that wasn't mentioned is that on a 250A machine, to be mindful of the duty cycle, weld for too long at max amps and your unit may just cut out if it has a temp control switch, if it doesn't, it may reduce the output of the current mid weld and in the worse case you may end up needing a new circuit board. A lot of 250A 240V welders are overrated regarding their output and/or have poor duty cycles at max amps.

 

[prepman]

Thanks for the response. I will get hold of some thick plate as you suggest and have a go.

My mig is 240 amp, so if I take your second welder spec "10mm plate to plate fillet - 1 run at 258-289 amps spray arc flat", this is not going to be possible as it's above the mig's capability. Therefore, would my machine be capable of a multi pass run to produce a strong weld, and if so would the root pass be made with the mig at full whack?

Of course I may be barking up the wrong tree, and it's as simple as if the mig can't weld a certain thickness in a single pass, then it won't be able to do so using multiple passes?

Perhaps I need to stop watching 'experts' on Youtube!

I've managed some really thick stuff maxed out at 200 amps, with multiple passes, but it was for my personal use and not structural (before someone leaps in). The whole piece was glowing red hot (which might not be tolerated) and fusion was good. As someone quite rightly stated the root has got to be good and successive passes are just a repeat of the same. I am NOT a professional welder, but have been mig/tig'ing 30yrs

 

[Nick DV]

One thing that wasn't mentioned is that on a 250A machine, to be mindful of the duty cycle, weld for too long at max amps and your unit may just cut out if it has a temp control switch, if it doesn't, it may reduce the output of the current mid weld and in the worse case you may end up needing a new circuit board. A lot of 250A 240V welders are overrated regarding their output and/or have poor duty cycles at max amps.

Thanks Ed, I fully appreciate what you are saying

I've managed some really thick stuff maxed out at 200 amps, with multiple passes, but it was for my personal use and not structural (before someone leaps in). The whole piece was glowing red hot (which might not be tolerated) and fusion was good. As someone quite rightly stated the root has got to be good and successive passes are just a repeat of the same. I am NOT a professional welder, but have been mig/tig'ing 30yrs

Thanks Prep, it’s time I gave it a go as it’s the only way I’ll find out, but getting hold of thick pieces of scrap to practice on isn’t easy

 

[prepman]

Thanks Ed, I fully appreciate what you are saying

Thanks Prep, it’s time I gave it a go as it’s the only way I’ll find out, but getting hold of thick pieces of scrap to practice on isn’t easy

By thick stuff I mean..... This is 3 pieces. No it hasn't been dye-penned, but has been tested in anger many times. They are ALL root welds built up with multi-passes. Ground up to finish off. I use pub gas CO² always have and being a cheapskate always will.

 

[prepman]

I guess it was an unintended auto-correct. A Stinger (originally a product name) is slang for an electrode holder. Very common in some places.

Jack

Maybe confused with 'Singer' who made sewing machines?

 

[Nick DV]

By thick stuff I mean.....View attachment 331386This is 3 pieces. No it hasn't been dye-penned, but has been tested in anger many times. They are ALL root welds built up with multi-passes. Ground up to finish off. I use pub gas CO² always have and being a cheapskate always will.

Are you saying this was with a 200amp welder?