Thread: How many amps do I *really* need?

i would forget the mig go for a decent inverter stick welder you can weld all of your wants with a 160a machine
vertical up is the only way to performa structual weld thats a australian standard
vertical down is only recomended for very thin material eg 2mm down but i still go up

If you refer back to my first post I was talking about welding 2-3mm steel and didn't mention structural welding. There are many more kg's of weld put down vertical down than any other position. Any fabrication work including high pressure gas lines, all sheet work where possible and I have seen up to 50mm plate welded vertical down. The reason is when you have the amps and everything going for you you can put down about 3-5 times as much weld which has a much smoother finish which will be less likely to lead to fatigue cracking.

Now I am not talking about some important weld on some earthmoving equipment or the weld that holds some highrise up or a repair to something that wasn't built strong enough to begin with. I'm also not talking about trying to weld 4mm with only 165 amps.

Any one who welds especially with a mig who doesn't do some vertical down welding isn't getting the most out of their welder.

Originally Posted by aussiecolector

There are many more kg's of weld put down vertical down than any other position. Any fabrication work including high pressure gas lines, all sheet work where possible and I have seen up to 50mm plate welded vertical down.

So vertical down is preferred to flat welding? I dont think so.[/quote]

Originally Posted by aussiecolector

The reason is when you have the amps and everything going for you you can put down about 3-5 times as much weld

But no penetration

Originally Posted by aussiecolector

which has a much smoother finish which will be less likely to lead to fatigue cracking.

Right..

Originally Posted by aussiecolector

Now I am not talking about some important weld on some earthmoving equipment or the weld that holds some highrise up or a repair to something that wasn't built strong enough to begin with.

Obviously.

Originally Posted by aussiecolector

Any one who welds especially with a mig who doesn't do some vertical down welding isn't getting the most out of their welder.

Ill try it next time Im bored with welds that have penetration and hold the job together.

Not wishing to hijack this fine thread.

But.
Not once did the vert down weld rate any significant mention when I did Pressure Plate at the School of Mines in Ballarat many years ago.

It rated a mention, and it was the last resort weld to do if there is no other way to weld something.

This says it all really..

Originally Posted by aussiecolector

There are many more kg's of weld put down vertical down than any other position. Any fabrication work including high pressure gas lines, all sheet work where possible and I have seen up to 50mm plate welded vertical down.
Any one who welds especially with a mig who doesn't do some vertical down welding isn't getting the most out of their welder.

aussiecolector

I believe you are very,very wrong in much of what you have written. I cannot let it pass as I believe there is a potential safety issue here.
I don't think I missed the "its ok to do vertical down bits" when reading AS 2885 Pipelines Gas and Liquid Petroleum and the SAA 1697 Pipeline Code.

Perhaps your shops had a different WPS than the rest of us.

It is a Change in Essential Variables.Big NO NO without a re qualification of the procedure.

Some open root pass work certainly can be done vertical down.Fill and cover butt passes in pressure pipeline can not.The simple reason is the a vertical down pass (by virtue of the nature of molten metal to obey the laws of gravity) has to be achieved with a fairly quick technique. Downwards travel with a large fluid weld pool atypical of a fill or cover pass means the operator needs to go like the clappers- result-too fast for adequate penetration.

Amperage alone does not provide penetration.Travel speed and wire stick out has a bearing on it as well .
Seeing such procedures carried doesn't account for validity of the practice -it indicates that the shops involved in this practice were probably cowboy outfits. Such places are usually shortlived as their work will come back to them eventually and bite them on the bum.
Try a comparison etch test of vertical down coupons and vertical up coupons. There will be a discernible difference in penetration depths.I have performed many such tests as an Accredited Testing Officer AS testing for AS 1796 Welding Certificates in Queensland.

To make a general statement like you have is misleading at best. We have some dam fine people here who are amateur welders. There is potential here for those people to utilise this information in the wrong context and get into some real strife.

There are limited situations where vertical down is acceptable such as sheet metal where the very limited penetration can be used to advantage or certain root run passes in open root pipe and plate work were again a minimum level of penetration is required.

This a pretty good forum and I for one don't wish to see it dragged down with one of our members involved in liturgation because a weld failed and some one got hurt or even worse, killed.

By all means fellow forum members, do some research on this topic and just don't take my word for it.
regards
Grahame

Hi Rodger,
I sincerely apologize to you as I got distracted elsewhere and should have replied to you first as the originator of the thread.

Regarding your intended purchase of the Cigweld machine. We all start out with the best intentions (of what we want to achieve ),but somewhere along the line things have a way of changing. I would surmise as has been the case of nearly everyone I know that down the track a bit ,you will find find the machine is not big enough.


Its a heap of cash to drop on a machine so your first choice had better be a good one.

A point not mentioned was the spool size. The smaller spool makes for less weight and better portability,but when it comes to cost you are paying considerably more for your wire per kilo.

Many of us will want to experiment with the different metals available and eventually you may find that you want to weld aluminium. This little machine won't do it. Aluminium on these machines requires a small OD wire so it will burn efficiently with the smaller max amps available.In turn the smaller wire size lead to wire drive snarls.

Having said that, if your mind is made up, at least go an try you machine at the dealers as once you paid for it it is hard to return because you do not like it..Also check out what accessories come with it particularly the regulator. Some don't supply a reg as part of the start up kit -it is an extra.

In answer to this <So how much (linear travel) 4mm work would I likely be doing in, say, a one-hour period?> at 200mms / minute -your 20% duty factor maybe 10 meters if you're a robot and don't stop .For the rest of rest of us-maybe 6 or 7 meters per hour.

I hope this helps
Grahame

Any fabrication work including high pressure gas lines, all sheet work where possible and I have seen up to 50mm plate welded vertical down.

I worked on the SA-NSW border run of this countries biggest gas pipeline for 3mnths as a pipeline welder (Internal). That is another story, but the info that you posted, as quoted above is B.S.

I realise it has already been covered by others, but when I saw your post I felt I had to reply anyway.

Fossil.

Grahame and Brickie, thanks for your comments. When I get beaten over the head often enough, with a big enough stick, I eventually get the idea. So it seems that less than 200A is out. It was never carved in stone, just seemed particularly desirable. And I take your point about the low-amps/thin-wire/feed-snarls for Ali work. I knew about all three points, but hadn't made that connection. Thanks also for the linear-travel indication.

I looked at the Weldmaster that Brickie got, and the WIA, Liquid Arc, and Transmig, all in the 220 - 250A range. The Miller, Esab, Lincoln, etc are too rich altogether for me.

Hmmm... SIL has just been around here, so I discussed it further with him. He said 220A, and if I need to do anything bigger I can use his shop gear. I was a bit surprised when he steered me off the Liquid Arc range, although he also said their wire and rods are second-to-none. So right now I am looking at the Weldmaster Mig220 which, at $1595 incl GST, seems like the best bang for my buck.

Again, I would like to thank everyone for their input... but... I still haven't seen an explanation of why some people assert that they can do satisfactory (large-fillet?) work on thick material with smaller machines. Is it that it is, in fact, possible, but very slow, or ...???

I feel that there must be a story lurking in there somewhere. One thing's for sure, I have a lot of learning to do.

Regards,

Roger

Originally Posted by rlincolnh

So right now I am looking at the Weldmaster Mig220 which, at $1595 incl GST, seems like the best bang for my buck.

Dont forget that those machines come without the hand piece which is another $140 for a 3M binzel style.

Originally Posted by rlincolnh

Again, I would like to thank everyone for their input... but... I still haven't seen an explanation of why some people assert that they can do satisfactory (large-fillet?) work on thick material with smaller machines. Is it that it is, in fact, possible, but very slow, or ...???

I think the claim is either a beat up or they pre heat, if you have to pre heat you need a torch which is more expense.
Maybe its the manufacturers claims that are exaggerated?

You wont be disappointed with the Weldmaster I am more than happy with mine.
If you buy from the same mob I got mine from, again you will be very happy with the service, it took 3 days from ordering to get to my place in Melbourne and they are in Campbelltown NSW..

Yeah, discountwelding seem to have the best price. Thanks for pointing out the missing gun - I was blinded by the price, and the 40% @ 220A rating, which seems pretty good for a single-phase machine.

When I look at the gun page, it starts all over again - more styles than I could poke a stick at! I presume (??) that there is some degree of standardization of the connector so that several different types could be used an the one machine. So what does it come down to when selecting a gun?

Roger

Roger
There are few criteria for mig gun selection,

Brands-
Tweco, Bernard and Binzel were the big names now copied by all and sundry.The main difference being noticeable to me in the contact tip and nozzle shroud mountings. For instance I like a nozzle that can pull straight off for cleaning and a 1/4 turn cam lock fit contact tip. Others have screw in fittings.I can't remember who had what, other than the Bernard had the trigger on top which I hated.

Ergonomics
Some welders like the trigger on top,some on the bottom,some triggers have a latch to lock on for continuous welding.

Amperage
A 250 amp capacity is more than ample for your 200 amp machine

Attachment
Two types , that I am aware off
Euro connection - All in one ,quick connect and disconnect.
Standard spigot fittings,slow,fiddly and old came out when the arc was built.Gas ,wire feed and electricals are all 4 separate connections.

Length of cable
Some ,not all, are available with varied cable lengths to suit operator requirements.

This is off the top of my head ,if I remember more ,I will post, but you should be able to select something from that lot and asking the right questions to the vendor.

Cheers
Grahame

Hi everyone been lurking for a while and decided to post eventually.

"My requirements will be from thin (1/2/3 mm) fabrications (turned, milled parts onto bits of angle, etc) to frames of about 4mm WT square tube, with similar thickness brackets etc to be attached."

I do agree with all said re the size. (No to vertical up) You may well get by with 140-180 but it wont be long before you regret not getting 200+.
With Migs my preferences lie with Lincolns, SAF's and Arc Liquide's .
With guns I swapped all my welders over to Kempi's with the large ribbed liner as its all aluminium mig welding and with 1.0mm and 1.2mm wire its no problems with the 4.5m lead even with twists.

If you have no experience in welding and want to go down to 1.0mm wall , have you considered a Tig? especially if its all stainless or mild steel (AC tigs for ally is another story). Much better for thin wall and you have the option to Stick weld also. A 160 Essetti will just handle a 4.0mm rod in stick.
My preferences there are Essetti's for small and Lincoln's for bigger AC ones.
With little experience in Mig welding 1.0mm stuff will end in tears.


Edit: I just noticed I said :"(No to vertical up)" Sorry that was a mistake vert. down is the easiest way to have no penetration and inclusion etc.

Thanks Grahame, that gives me something to go on.

Riley, I take your point about no-experience/1mm-walls. I must say that 1mm is at the bottom of the list for most of the work that I envisage. I hope that by the time I get there, I will have a reasonable amount of experience with (mostly) 3mm. I have seen some beautiful smaller work done with tig, and I expect that I will give it a go at some stage. Ease of learning was one of the driving forces in my choice of mig as the first step into welding.

What was behind your comment <(AC tigs for ally is another story)>? Was it just with regard to the high cost of a good AC tig, or was there more to it?

Maybe a subject for a new thread, but just what is the great difficulty with tig work? On the face of it, it appears completely analogous to ordinary oxy-acetylene work, yet any mention of it brings an instant response along the lines of 'oh, yes, difficult though, yes, very hard...'.

Roger

Originally Posted by rlincolnh

Thanks Grahame, that gives me something to go on.

Riley, I take your point about no-experience/1mm-walls. I must say that 1mm is at the bottom of the list for most of the work that I envisage. I hope that by the time I get there, I will have a reasonable amount of experience with (mostly) 3mm. I have seen some beautiful smaller work done with tig, and I expect that I will give it a go at some stage. Ease of learning was one of the driving forces in my choice of mig as the first step into welding.

IMHO a Mig is not the most appropriate machine for 1 and 2 mm material.

Originally Posted by rlincolnh

What was behind your comment <(AC tigs for ally is another story)>? Was it just with regard to the high cost of a good AC tig, or was there more to it?

To have a AC tig you are either looking at a inverter .The pluses are size and 240v, minuses cost. Or a 3 phase if non inverter type .You will find you will tend to max out at 4-5mm wall on straight Argon 1/4" at a pinch with He/Ar mix with a 180amp Ac Tig on Aluminium.Over 200amps you are paying big money for a good one.

Originally Posted by rlincolnh

Maybe a subject for a new thread, but just what is the great difficulty with tig work? On the face of it, it appears completely analogous to ordinary oxy-acetylene work, yet any mention of it brings an instant response along the lines of 'oh, yes, difficult though, yes, very hard...'.

Roger

The jump from Oxy to tig is a small one .As with mig Tig is all practice. With beginners I do believe you have more awareness of penetration.