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> Air-cooled torch MIG spray 8mmLL fillet recommend?
post May 20 2018, 03:12 AM
Joined: 14-Jan 07

Doing lots of 8mm (5/16th-inch) leg-length T-fillets in the PB/2F position, structural steels.

Firstly - what Amps for a natural 8mm fillet? Searching online suggests 300A. I suspect that's minimum / low-side? Reason I have to ask is; I've never had a torch which would take the Amps for a natural 8mm fillet run!!

No water-cooling facility, so...

What recommendation for an air-cooled torch which will do 8mm fillets spray-transfer all day every day?

I see Tweco do a monster torch - the "Spraymaster". Sounds promising! Is this it? The torch specifically for this task?
If so
- go for the 350 or the 450?
- who sells them? Got wary answers, as Tweco offer options and some suppliers don't seem to know how to ask for what will fit on a standard UK / European MIG machine.

What is the upper limit of a Binzel MB36 - in reality?!

Help me out here folks! I've suffered a lot of "rough" - now I want some "smooth" (as in "take the rough with the smooth")

Try Some

This post has been edited by try_some_welding: May 20 2018, 03:13 AM
post May 20 2018, 09:48 AM
Joined: 23-Aug 08

What size wire are you using and what type of wire, solid, metal, rutile or basic cored?

I presume we are talking MAG and not MIG?

300 amps for a 8mm leg length or a5mm fillet weld, seems to me to be a tad on the high side.
Somewhere around the 250 amps would be more realistic but then, that would depend on your wire size and type.
For optimal deposit speeds in the PB position a 1.2mm metal cored wire or a 1.0mm solid wire would be the wire of choice for a a5 mm fillet weld in the PB position, running at around 250 amps, 28volts top.

Hope this helps some,

This post has been edited by Boilerbuster: May 20 2018, 09:51 AM
post May 20 2018, 12:44 PM
Joined: 14-Jan 07


You are correct, correct and correct.

MAG (Ar-20%CO2-2%O2 - cann't change that)
solid wire
1.2mm dia wire

My impression Is that 240A gives 5.5mm to 6mm leg-length "natural" - perfect smooth mitre and clean with spray-cone landing at tip / "apex" of weld-pool?

I'm forced to a higher V than optimal and what you mention by the gas - but have to make do. It's less pretty but at least it's erring on the structurally sound side. Likely adds to the stress on the torch though.


post May 20 2018, 03:39 PM
Joined: 23-Aug 08

Sounds about right TSW, but your gas of choice or rather the one your stuck with tends to let things run a little too hot.

The 2% O2 is their to break the surface tension of the weld pool and give the weld a smoother finish with less spatter, which has some advantages when welding steels with a high alloy content like heat resistance steels.

The down side of it is that you don't really want O2 near your weld pool for obvious reasons. Just stick to a 2 component gas like 85/15 if you can for normal construction steels like S355 or less.

post May 20 2018, 07:04 PM
Joined: 14-Jan 07

Thanks for passing experienced eye over what I think I am doing.

So - on to the torch. All are undersized.

I was thinking of getting my own torch - either the Co. likes what I am doing and keeps me on in various
capacities or I get to be like a "journeyperson" who can move from one good job to another, bringing something special and the means to deliver it.

Largest real capability common torch I know of is the Binzel MB36.
What will that really do?
Can that do 8mm fillet single-run all day long?
If you helped it with a fine "spider-silk" jet of water onto the cooling fin(s) between each job, will that keep it in duty-cycle?

Then there is this "monster" Tweco I will get onto Esab UK about (Esab own Tweco) - is it right and where could I get one?

Experience please on air-cooled torches at 8mm fillet-size?!

post Jun 2 2018, 04:04 PM
Joined: 19-Oct 07

You should take a look at the Abi Mig Pro range of torches from Binzel.

They have a Abi Mig 355 which is a newer, better version of a MB 36. Takes a M8 Thread contact tip as standard, built in tip adaptor and gas diffuser and screw on shroud. They do a even bigger version called a 455, which is rated at 450 amps. I regularly use the 355 heavy duty version on advanced Pulse processes up to about 6mm thick.

The Gas mix and process will make a Difference to the performance of the torch, the higher the Argon content the greater the duty cycle of the torch will be reduced. Pulse and the increased deposition processes are even more demanding on the torch.

Pulse welding on Aluminium with 100% Argon is pretty much the worst combination as regards the torch because as well as the process and the gas you also have to factor in the reflective heat and UV off the shiney plate
post Jun 13 2018, 05:32 AM
Joined: 14-Jan 07

Thanks @matt1978
Voice of a lot of experience carries-across there.

Reporting back from my end - I was back on heavier sections, got my 5mins of sweet welding then into the endless struggle, body language must have said something when I went around the shop office - and lo-and-behold would you believe it I find myself with a Tweco #4 Classic which they had hidden in the woodwork.

It does the job.
I'm getting those 8mm fillets straight run, clean even despite 20%CO2, at about 290A and 13m/min WFS with this 1.2mm solid wire.
Getting wetted-in edges and a reasonable 45deg flattish profile.

I got a telling-off from the welding equipment people that this is nothing.
It's the place of pain so many of us endure in general steel fab. shops where we never meet anything but undersized equipment - the equivalent of turning up with a toffee-hammer to dig a railway tunnel through the Rockies.

More good news - my welds are completely clean on MT/magpart, not even a few spurious indications to discount - where that isn't entirely the case elsewhere...

Thanks matt and everyone.
Try Some
post Jun 28 2018, 10:40 PM
Joined: 15-Oct 09

I would go for a Bernard EZ Feed 300 or 400. Outlasts any other torches on Duty Cycle. I would run 1.2mm solid wire at 300A and 30V for an 8mm leg length fillet. Great contact tips, no thread, they are elliptical and 1/4 turn and they are released.
Note: make sure you get GENUINE Bernard torch and tips
Let me know how you get on.
post Aug 17 2018, 09:53 PM
Joined: 14-Jan 07

QUOTE (readywelderuk @ Jun 28 2018, 11:40 PM) *
I would go for a Bernard EZ Feed 300 or 400. Outlasts any other torches on Duty Cycle. I would run 1.2mm solid wire at 300A and 30V for an 8mm leg length fillet. Great contact tips, no thread, they are elliptical and 1/4 turn and they are released.
Note: make sure you get GENUINE Bernard torch and tips
Let me know how you get on.

I turned green and grew in height and width and nearly busted the frame around the factory manager's door.
Surprise upon surprise - a Tweco #4 "classic" appears.
Rated at 400A on the "reference case" 100%CO2, the 20% derated-for-argomix still leaves headroom for an 8mm leg-length single-run fillet.
The good conditions did prove to be around 300A. I never got to use my clamp-meter, as the difficulties of working meant you were never caught-up with the job.

The important point is that the approach I hoped would work did work.
I suspect that, on 20%CO2 argomix, the volts had to be so scorching hot to get a clean arc, and that gave monster penetration above and beyond what is needed.

I did get good welds which were unlike anything which anyone had see before.

I've moved on from that job now. All torches are water-cooled so small torches are fine.

Try Some
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