Welder Capacity at Lower End

[Oldneweng]

I am wondering whether is is worth buying a new welder, multi process or just Mig. My current welder is good at everything I have tried(Mig & Arc. Not used Tig yet) except it has a lower voltage limit for mig of 17.5v. This is too high for thinner metals.

I would like to find out just what is regarded as suitable values for various thin sheets. I want to weld down to 1.0mm steel. These specifications are often not mentioned in brochures web pages etc. I need to know what I am looking for before I start asking for information.

Dean

[Grahame Collins]

Hi Dean
How thin are the thinner metals you want to weld?

Traditional welding wisdom has it that the rule of thumb was a thousandth of an inch metal thickness per set amp.

I have seen mig used for vehicular sheet metal which I believe is .6m.
The single phase mig was running .6mm (.025" ) wire.

The weld turned out Ok but remember one could do this with say Co2 as some have chosen as their alternate Sheilding gas.

Another thing worth a mention is that the welds had a copper backing shield ( flattened copper pipe on a stick-Hi tech!) and the weld procedure was worked out to minimise heat input - welding in sequences.

More details will help.

Grahame

[KBs PensNmore]

As what Grahame said about the copper backing, an aluminium block works great also. Your welder, what brand and size is it? Have you tried your lowest settings and worked up? A photo would help of the control panel also please. I've 250 amp CIG mig that I use for welding bandsaw blades with out any problems, so I don't think it's the size of the welder.
Kryn

[Oldneweng]

Hi Dean
How thin are the thinner metals you want to weld?

I would like to find out just what is regarded as suitable values for various thin sheets. I want to weld down to 1.0mm steel.

At least.

At this stage I am only looking at welding steel.

Another thing worth a mention is that the welds had a copper backing shield ( flattened copper pipe on a stick-Hi tech!) and the weld procedure was worked out to minimise heat input - welding in sequences.

As what Grahame said about the copper backing, an aluminium block works great also.

I have done this with a ride-on mower blade that split from the bolt hole. I want to be able to weld without special treatments like this however.

Assume I am looking at buying a welder. For a decent range of metal thickness capabilities from 1mm up to 10mm, what range of specifications should I look for to ensure this capability.

I am not asking for troubleshooting on my existing welder.

I've 250 amp CIG mig that I use for welding bandsaw blades with out any problems, so I don't think it's the size of the welder.

No, it is the bottom range the welder is capable of.

Cheers

Dean

[Grahame Collins]

I am wondering whether is is worth buying a new welder, multi process or just Mig. My current welder is good at everything I have tried(Mig & Arc. Not used Tig yet) except it has a lower voltage limit for mig of 17.5v. This is too high for thinner metals.


Dean

Hi Dean
Sorry I missed the size to weld down to in your initial post.These days I have increase the page size to read posts.

Bear in mind that the machine supply current that suits MIG does not necessarily apply to TIG as far as the power supply goes and as its a multi process unit - by definition is an an inverter, so in that way sort of limits my knowledge a bit. I left the TAFE system before Inverters became mainstream and did not have up to date info on inverters in those days. Pre inverter I could tell you about welder power supplies it in boring detail.

I suspect the CC - Constant Current still applies for MMAW and TIG while CV - Constant is the applicable current source for MIG. The amperage has more to do with
this than the Voltage. Where did this 17.5V spec come from?

Not having used the Tig you can't say if it will work or not as the arc voltage is affected by arc length. I assume also you realise that the shielding gas will be pure argon not an argon /oxygen, Co2 mix. The mix shielding gas is too hot for tig welding on steel.

I would certainly trial it first even if you have to borrow a cylinder of argon before lashing out on a new machine.

What make and model is the machine? Is it a Cigweld 175i. What ever it is some more info on the make and model will really help to pin this down.

Grahame

[Oldneweng]

Where did this 17.5V spec come from?

Inverter Migs are adjusted using voltage. My welder (BOC Smootharc 175) adjusts from 17.5v to 25.5v. I saw one of those on EBay tonight and looked at the listing to see the specs. It is meant to go down to 16.5v, but this still equates to a range of 50 - 175A. Apparently mine does not even go that low.

Not having used the Tig you can't say if it will work or not as the arc voltage is affected by arc length. I assume also you realise that the shielding gas will be pure argon not an argon /oxygen, Co2 mix. The mix shielding gas is too hot for tig welding on steel.

I would certainly trial it first even if you have to borrow a cylinder of argon before lashing out on a new machine.

I would like to try the Tig but I don't know anybody that owns one that I could borrow a cylinder from. I have been wondering about buying cylinders.

I have been doing some reading and have seen the suggestion that for 0.8 - 1.2mm steel 40A is ok, but a bit less is even better.

Dean

[Grahame Collins]

I think you are right.

50 amps for a 1mm butt sounds too much. What I forgot as well,was that inverters typically run a lower than the old tranny machines.
So for a 1mm butt I would estimate an amperage in the region of 30 to 35 amps which you won't get if your BOC bottoms out at 50 amps.

It may be worth looking at one of the lunch box sized welders. Get em to plug one in ,at the store and see how far the amps can be wound down.

Grahame

[Michael G]

I would like to try the Tig but I don't know anybody that owns one that I could borrow a cylinder from. I have been wondering about buying cylinders.

TIG could well solve your problem. I use stick for the thick stuff and TIG for thin, and weld 1mm steel quite easily (I won't say well, but that's my skill level rather than the process as my co-workers are gleefully point out)

I've been thinking for some time about buying a cylinder too as currently I rent. Because I do rent I'm not keen on lending the cylinder (and I do use it every few weeks as well) but we do have Power 10 outlets around. PM me for further discussions but I guess that we could probably come to an arrangement where either you bought an E size, tried it and if you did not like it I'd buy it from you (does the agreement allow for transfer of cylinder ownership? - it should but...). The other option would be that I buy the cylinder and while I still have the rental you could borrow the bought one. Any of those options sound as if they might work for you?

Michael

[Michael G]

So for a 1mm butt I would estimate an amperage in the region of 30 to 35 amps which you won't get if your BOC bottoms out at 50 amps.

It may be worth looking at one of the lunch box sized welders. Get em to plug one in ,at the store and see how far the amps can be wound down.

Would Dean be running out of electrode range then though? I weld stick on DC but notice that my universally used 2.5 rod (WIA 12P) is reluctant to start and run below say 50A.
I did buy some 2mm and 1.6mm electrodes once to try and get lower but found that they were too whippy for me to be able to keep pointed in exactly the place I wanted them. Still around I think if someone has steady enough hands to use those sizes...

Michael

[Harry72]

If you going to do 1mm and under a TIG is a good option, I've been running mine at 55~70 amps(depending on joint type) on 150mm galv C section(1mm thick)after removing the galv coating.
You dont really need to run a foot pedal on thin steel providing your machine can adjust up and down ramp, you just control the heat by arc length and travel speed and by how much filler rod you are adding, if its getting too hot just button off for a second or two

The trick with TIG on thin stuff is to run it fast and hot... its a bit counter intuitive but slower you go the bigger HAZ because your keeping the heat on longer!
When tacking I up the amps to 90 with no ramping... just hit the button and let it have it for a second... KA'POW

[Gavin Newman]

I did buy some 2mm and 1.6mm electrodes once to try and get lower but found that they were too whippy for me to be able to keep pointed in exactly the place I wanted them. Still around I think if someone has steady enough hands to use those sizes...

Michael

Where did you get the 1.6 rods from? In the workshop I use the TIG or MIG for thin stuff but at the track I'm limited to the stick welder and I'd like to try 1.6 now I have the Fronius.

[Grahame Collins]

Would Dean be running out of electrode range then though? I weld stick on DC but notice that my universally used 2.5 rod (WIA 12P) is reluctant to start and run below say 50A.
I did buy some 2mm and 1.6mm electrodes once to try and get lower but found that they were too whippy for me to be able to keep pointed in exactly the place I wanted them. Still around I think if someone has steady enough hands to use those sizes...

Michael

Deans post referred to TIG but the principal is the same in that in his machine can only go down to 50 amps, still way too high for 1mm sheet.


Your small diameter electrodes.Were they Gemini's ,as they come in those electrode diameters? I found I had better success in cutting the 1.6mm electrodes in half to prevent the wippiness described.I think it was RustyArc who suggested it.

The small diameter Geminis are prone to absorbing moisture by nature of their thin flux cover.They had to be warmed. A lot of the electrodes stored in the PVC tube had spalling and heavy rust on the electrode wire makes me question if the lid on the PVC storage tube was tight.

Moisture take up makes them a bit fierce to use, particularly on the initial strike. Moisture affected electrodes are bit hard on thinwall material, tending to blow holes on the initial arc strike.

After a warm up with the LPG torch they behave themselves.

[Michael G]

Where did you get the 1.6 rods from? In the workshop I use the TIG or MIG for thin stuff but at the track I'm limited to the stick welder and I'd like to try 1.6 now I have the Fronius.

They are 'Blue Demon' 6013 electrodes brought in from the US. I have a 1lb tube of 5/64" (2mm - unopened) and a 1lb tube of 1/16" (1.6mm - minus 1 or 2). Send me a PM if you want them and we can arrange transfer. Now that I have a TIG welder I'm unlikely to ever use them. (As Graham suggests, they may need drying but as they have been in plastic tubes ever since I've had them, I would not anticipate an issue)

Michael

[Oldneweng]

TIG could well solve your problem. I use stick for the thick stuff and TIG for thin, and weld 1mm steel quite easily (I won't say well, but that's my skill level rather than the process as my co-workers are gleefully point out)

I've been thinking for some time about buying a cylinder too as currently I rent. Because I do rent I'm not keen on lending the cylinder (and I do use it every few weeks as well) but we do have Power 10 outlets around. PM me for further discussions but I guess that we could probably come to an arrangement where either you bought an E size, tried it and if you did not like it I'd buy it from you (does the agreement allow for transfer of cylinder ownership? - it should but...). The other option would be that I buy the cylinder and while I still have the rental you could borrow the bought one. Any of those options sound as if they might work for you?

Michael

The agreement as I understand is the same as LPG cylinder exchange. You just swap it for a full cylinder and go, after paying for it of course.

I have not heard of Power 10. I just looked them up. My nearest store is Horsham which is 140km away. They will not exchange other suppliers cylinders. Then there is Speed Gas supplied by Gasweld in Mt Gambier, 90km away. I have a strong aversion to this Gasweld dealer, not store tho as they have screwed me in the past on a faulty Mig welder. I haven't bought anything from them since. Prior to that I bought nearly everything from them. I fixed the welder myself.

Thanks for the offers Michael. I will have to think about it. At the moment I am gathering information to help me with making a decision.

I think you are right.

50 amps for a 1mm butt sounds too much. What I forgot as well,was that inverters typically run a lower than the old tranny machines.
So for a 1mm butt I would estimate an amperage in the region of 30 to 35 amps which you won't get if your BOC bottoms out at 50 amps.

It may be worth looking at one of the lunch box sized welders. Get em to plug one in ,at the store and see how far the amps can be wound down.

Grahame

Would Dean be running out of electrode range then though? I weld stick on DC but notice that my universally used 2.5 rod (WIA 12P) is reluctant to start and run below say 50A.
I did buy some 2mm and 1.6mm electrodes once to try and get lower but found that they were too whippy for me to be able to keep pointed in exactly the place I wanted them. Still around I think if someone has steady enough hands to use those sizes...

Michael

My welder will go down to 20A stick welding (10A Tig). It is only the Mig that is a problem. I have looked at other BOC welders and they all seem to have this 50A lower limit for some reason. I guess crash repairers don't buy from BOC.

I have tried small rods before with some success but I am not sure whether my hands are steady enough anymore. I guess this is one thing I can at least try without spending too much.

One job I have to do is repairing an old rusty 8 x 5 trailer for a friend. I offered to repair it to usuable condition in exchange for a "Lowline Heifer". The top edges are rusted where the stock crate is sitting. The top edge is folded with an upsidedown Vee. The crate base is angle that rests on top of this Vee. I don't know how thick the metal is but I guess about 2mm. The chassis has some issues as well, but I don't see any problems with the welding here.

If you going to do 1mm and under a TIG is a good option, I've been running mine at 55~70 amps(depending on joint type) on 150mm galv C section(1mm thick)after removing the galv coating.
You dont really need to run a foot pedal on thin steel providing your machine can adjust up and down ramp, you just control the heat by arc length and travel speed and by how much filler rod you are adding, if its getting too hot just button off for a second or two

The trick with TIG on thin stuff is to run it fast and hot... its a bit counter intuitive but slower you go the bigger HAZ because your keeping the heat on longer!
When tacking I up the amps to 90 with no ramping... just hit the button and let it have it for a second... KA'POW

I have thought about Tig, but I have never used it so I don't know anything about it. Would you use Tig for seams on a trailer for example. Mostly the thin metal work will be shorter lengths, but I can picture some longer seam needs.

Maybe I could rent a smaller cylinder for a short period and concentrate on learning with it. This would apply to both Tig and Mig with gas as I have only tried my welder with gas for a couple of minutes without much success. I will have another go. This was only CO2 in a little disposable cylinder.

Dean

[Karl Robbers]

According to the Lincoln welding parameters app, assuming .9mm sheet and .9 solid wire with CO2 shielding gas, you would run 18v and 2.5m/min wire. Drop down to .8 wire and you need 18v and 3.2m/min. If mixed gas is your choice, then voltages drop down to 16v, so out of your range unfortunately.
The lower end of a welder's range is what separates the men from the boys as any machine can run a weld turned up, but finesse comes into play when welding foil thicknesses.
If you already have the gas and wire, give it a go and see what happens.
How much welding you do on 1mm thicknesses will determine the need to set up specifically for it, such as .6 wire or tig. Tigging 1mm, you will need a steady hand and good eyesight, migging it will still need decent eyesight, but steadiness of hand will be a little less demanding.