Thread: Me and MIG

This thread is about me learning to MIG weld.

I’ve been welding for about 30 years now. All stick until about 3 years ago when I got myself an AC/DC TIG machine. I’ve never touched a MIG machine before. Literally.

Now… I love my TIG welder, but lately I’ve had heaps of projects with thin galvanised RHS and tube that is just a pain with TIG, no matter how well you try and clean the crap off. Stick welding is a great process and has been my long-term friend, but sometimes there’s a better solution: and I reckon MIG might be it.

I know someone’s gonna say it, so I’ll beat them to it… technically, I won’t actually be MIG welding that often (although I do intend to try some aluminium project later). I know I should be referring to it as GMAW or MAG or whatever, but then I’d sound like I knew what I was talking about, so I’m going keep calling it MIG.

Anyway, I’ll try and throw some photos in and some links to good stuff I find along the way. It’s be great if you guys can throw in advice, suggestions and comments as you see fit.

Thanks

- Mick

About a month ago a mate dropped off a 3/4 full G bottle of argoshield light. It's a long story, but basically I've got it till the end of June before rent's due. So plenty of time to practice with the good stuff. I figured this would be great to learn with, but might switch to self owned CO2 after I get the hang of MIG. I'm already renting one bottle for TIG argon, so not enthralled with the prospect of renting 2 bottles long-term.

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I ordered a brand new MIG machine on Tuesday night, and it arrived today about 36 hours later. Haven't really looked at anything yet. I'll pull it all out over the weekend and see what's what. The machine is from Tokentools (same as my TIG welder), it's called a Metalmaster 210S. This exact model isn't actually listed on their web site but it is basically the synergic version of the MIG 210D.

If you don't know what synergic means then don't feel bad. I had no idea. On a practical level I think it basically just means that the machine is pre-programmed with a heap of settings to get you up and running for all sorts of combinations of wire diameter, metal type, and whatever. You can tweak these settings or override them completely. I'm sort of counting on this synergic business getting me up to speed pretty quickly.

While driving around today I also grabbed 26m of 30mm SHS for a frame I've got to make up over the weekend and a 5Kg spool of wire (ER70S6). The 9mm wire was sold out, so I grabbed the 8mm. The price seemed alright at $25 from the toolspot. I also grabbed some MIG pliers.

You didn't mention the section thickness of the SHS, but either way, expect to have some fun with the metal glue gun

In most respects, after stick, it's easier than falling off a log, but on the other hand, it's sometimes surprisingly difficult to get as good a looking weld profile as you get with a good stick run.

The SHS for the frame is 2mm wall thickness. Manageable enough with stick, but a good candidate for my first MIG project. I'm really curious to try the mig. I'm pretty sure it's not going to be as easy as it looks.

Well nothing unexpected on unpacking. All well packed with foam and strapping and everything present and accounted for. I forgot to ask if an argon/CO2 regulator was included in the package (it’s not), so you have to order one as well if you need one.
Here’s a photo of the bits and pieces.

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The only thing in the photo that is additional to standard is the flex head for the TIG torch. I was pretty impressed with the MIG torch – solid, but light and had a good trigger guard. The side door on the welder was catching on a small piece of mis-aligned plastic. The Stanley knife took care of that. The cabling and size of connectors is beefier than my old welder (which is the around the same amperage).

The manual is pretty funny. One of the first headings is “prolegomenon”. It’s not the best manual I’ve ever seen, but then again you don’t really need it. I read the bit about setting up the wire feeder and left it at that.

Everything connected up quickly and I was ready to turn on in about 10 minutes. I fed the wire through no problems, then did a bit of fiddling with the tensioner to make sure it was on too tight. I then loosened wire roller loose while I purged the gas through the lines (i.e. press the trigger but don’t feed wire). Once that was done I reset the feeder tension and was right to go. First welds coming up.

The whole synergic thing certainly does get you to a starting point quicker. I just selected 0.8mm wire, set the mode to Steel, turned on post-flow and as far as I could tell I was ready to weld. So I did:

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These are my very first MIG welds ever. The top weld in the first photo (the one on the right in the 2nd photo) was #1. Both photos are of the same welds but from different angles. As you can see, I didn't bother cleaning the base metal - I was a little too eager.

Looking at the 2nd photo you will notice these welds are too high in profile. With the 4th weld from the right I tried a quicker travel speed and it was only the 5th from the right before I tried increasing the voltage/amps. Still a bit cold for my liking.

I grabbed a bit of gal SHS (50 x 2mm) and tried tacking it and welding a butt joint:
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This first one was a bit hot near the end and you can see a crack forming in the crater.

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I found tacking was hard to keep neat (compared to TIG). The weld was done pushing the torch (right to left) rather than pulling. I found the lack of visibility with pulling the torch a problem. As you can see, it's not the neatest, but I was happy with the penetration (just a bit of key holing). The big build up on the right hand side of the middle photo was a result of running up over a high tack, but generally the weld profile was reasonable, if not still a bit high.

I squeezed out a couple more beads before I had to go:

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My torch typically looked like this after a weld:

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It might sound stupid, but I actually wasn't sure how to initiate the arc. You'll see in the first photo of the last post that there is a little bit of welding wire sitting below the first weld. I was initially trying to scratch start an arc, but off course too much wire came out. Later on I was just snipping off the wire short and letting the wire feed make contact. Is this how you do it?

Also I was finding that the start of the welds were a bit cold/high profile. With stick welding I would normally arc up say 1cm into the weld then backstep before welding back over my arc strike - this would heat up the start of the weld nicely. With the MIG it seemed to deposit too much metal to allow that.

How much splatter on the torch nozzle is normal? In those welds I've shown so far, I probably cleaned it out 3 times (quick scrape and a tap). Is this just due to the ill prepared base metal or is it a symptom of some poor setting?

I was basically just adjusting voltage to make a hotter weld. I was going to reduce the wire feed rate, but thought that would result in the wire burning back into the tip - so didn't try it this time? What's the strategy for getting a hotter weld, lower bead profile?

So guys - what can you help me with?

- Mick

A good start Mick, at the end of the welds on your tube just stop traveling and hold the trigger for a sec before lifting away, will help to avoid the crater.

For tacking I rest the nozzle on the tube so that the wire looks like its gunna miss the tube and then squeeze trigger on roll torch sideways so the wire contacts on the radius of the tube if you follow what I mean.

And finally for the nozzle get yourself a tin of nozzle dip or even use, I think from memory some cooking oil spray to stop the spatter sticking.

thanks DJ's. Nozzle dip? never heard of it - just like anti-splatter spray? With tacking, I can't quite picture what you're describing with the aiming/rolling. I'm going to have to watch a few youtube videos - it's raining here, so not a bad day for it.

Here you go Mick, I'm outside leaning over the bonnet of the troopy having a cold one or two

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So I walked down to the shed and took a couple of pics for ya

Start position

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Finish position

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And my nozzle dip, must be near 15 yrs when I bought it, lasts a longtime.

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Gotcha! you deserve another coldie for that

Originally Posted by WelderMick

Gotcha! you deserve another coldie for that

No worries, photographic evidence of another one um maybe two more

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is it me, or are your photos getting blurrier?

OK, the kids all fell into some sort of chocolate induced stupor around lunchtime, so I got to sneak off to the shed to start putting together my first MIG project. It’s a frame about 2.1m high made out of 30 x 2mm gal SHS. This is exactly the sort of work I got the MIG for, so I was keen to see if it was much an improvement over how I’d normally weld it with stick.

Cutting up the stock was a breeze with my little bandsaw. I've found the little stand I made up for it a real treat for cutting up long stock (I had 8m lengths) - as I just support one end on the workbench, and roll the saw up to where I want it, chop off a length, then roll to the next spot and repeat. It's almost as easy as an infeed/outfeed table, but takes up next to no space. http://www.woodworkforums.com/f65/ne...-stand-136989/ has a pic of the stand.

Back to the MIG. I decided to trust the synergic settings, which seem like they are pretty much optimised for this size metal. I used the same settings for all welds: butt welds, fillets, overhead. I still haven’t had enough time to test out settings versus weld performance… that’ll have to wait until I have a bit more time to play.

First off - tacks.
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Here's a typical tack up. It certainly does the job, but not always as neat as I'd like and too much filler metal. I'd rather burn the tack in deep so that could weld over the top neatly. There's also the little dimple in the the the tacks which I guess are from cooling too quickly. I'd really like some more tips on settings and techniques for tacking if you have any

Below's a butt and fillet weld from today. I'm pretty happy withe the butt welds now, although if you look closely, the edges of the weld aren't washing in. These welds are on straight gal without any preparation - so maybe that's it, or maybe not? Any comments?

On the fillet weld, you can see on the right hand side, there's a high spot. This is partly due to the big tacks shown earlier, but also due to a cold start. I can't seem to get a good burn in at the start of the weld without depositing a lot of metal. This has probably been my main issue to date in getting a weld I'm happy with.

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This is what I like about the MIG - it's easy to zip up little gaps with a quick downhill weld. It's not perfect obviously, but far better than I'd hope for with stick:

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Instead of doing up the whole frame on the ground, I figured I have a go a few overhead fillets:

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Most of them were OK, but sometimes the wire was melting back towards the tip and the arc was stuttering. You can see the left side of the weld is a bit off because of this. Also plenty of sparks in the hair - didn't have a cap .

Here's the frame, more or less completed, just got to ring up some ancillary hooks, etc. It's to hang geofabric bags which will be filled with sediment as part of some dredge spoil dewatering trials. The frame is surprisingly strong (I can hang my 100kg off the centre), but I'll probably add a central set of legs.

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Originally Posted by WelderMick

It might sound stupid, but I actually wasn't sure how to initiate the arc. You'll see in the first photo of the last post that there is a little bit of welding wire sitting below the first weld. I was initially trying to scratch start an arc, but off course too much wire came out. Later on I was just snipping off the wire short and letting the wire feed make contact. Is this how you do it?

Originally Posted by WelderMick

On non critical work, (non code), which will be virtually all your work I should imagine, the best way is to not worry too much about snipping off the balled end of the wire and to set your power high enough to burn in at the beginning when you pull the trigger and then travel at a suitable speed to not blow through the rest of the weld. It takes practice. A good rule of thumb with Mig is to always run your power at the highest level that you can handle for the material and position that you are working in. At the end of a run, pause or backstep to fill the crater, then release the trigger. Don't pull away as doing this interferes with the gas coverage and can cause porosity - worse with argon based gasses in my experience.

Also I was finding that the start of the welds were a bit cold/high profile. With stick welding I would normally arc up say 1cm into the weld then backstep before welding back over my arc strike - this would heat up the start of the weld nicely. With the MIG it seemed to deposit too much metal to allow that.

See above reply. Grinding your tacks, particularly those in the middle of a weld, will also alleviate this problem, but is impractical and unnecessary with thin tube work.

How much splatter on the torch nozzle is normal? In those welds I've shown so far, I probably cleaned it out 3 times (quick scrape and a tap). Is this just due to the ill prepared base metal or is it a symptom of some poor setting?

The level of spatter is related to shielding gas choice, material contamination and coatings (galvanising or duragal) as well as tuning of the welding parameters. Argoshield supposedly produces less spatter, but what it does produce sticks far worse than if CO2 was used. I personally don't use tip dip as it can cause weld contamination, (not really a problem unless working to code), as well as interfering with subsequent paint application. I have used spray on cooking oil when welding galvanised for 10-12 hours a day and it really does work. The effectiveness of any anti spatter dip/spray is diminished dramatically by a grungy, scarred nozzle.

I was basically just adjusting voltage to make a hotter weld. I was going to reduce the wire feed rate, but thought that would result in the wire burning back into the tip - so didn't try it this time? What's the strategy for getting a hotter weld, lower bead profile?

Tread carefully here. The Mig process works within a defined set of parameters. What this means is that the relationship between wire feed and voltage must be maintained within set values or else undesired side effects occur. For example, too much wire/too little voltage can lead to a lack of penetration and edge wetting, (the proverbial slug sitting on top of the parent metal), excess spatter, stubbing (when the wire tries to push the gun away from the work, sort of like a pistol recoiling). Too much voltage/too little wire results in a hot arc with a hissing sound and large droplets of metal being transferred splat hiss splat hiss if you get my drift. There can be undercut, a lack of penetration and a weak weld prone to cracking. In extreme cases, the wire will burn back to the tip and weld itself there.
Migs are largely tuned by sound and the sound we are after is a crisp crackle, like bacon frying in a nice hot pan, if it sounds like a machine gun, crack crack crack, then that will probably be too much wire and if we get the hissing sound, that will be too much voltage. These sounds don't apply to pulse migs which can have a sound somewhat like a 2 stroke chainsaw.
Voltage spreads the weld deposit, while wire controls penetration. So the crux of the matter is that the parameters can be tweaked and adjusted, but only to a certain point without detrimentally affecting the finished weldment.
To achieve your lower profile, you would probably crank both your wire feed and voltage up and travel quicker - the wire should always be at the leading edge of the puddle.
One of the most common mistakes made with a mig is to try to run too large a bead in one pass as penetration suffers greatly. For a bit of fun/research why not weld a few pieces of say 10-12mm plate together in a "T" section using varying settings and then break them with a press or sledge hammer and inspect the penetration and appearance thus demonstrating the effect that various adjustments have on the completed weld. Only weld one side of the "T" or else you will never break them.
Arguably, one of the greatest skills involved in Mig welding is setting the machine up, they are far from the point and pull device that many portray them to be. This is why I generally recommend stick welders to the handyman welder as generally if a stick weld looks good, it is, but a mig can and will produce a butter smooth weld that looks like it grew there, but holds nothing due to incorrect setup and/or technique. Pretty sobering when you consider that weld may be holding the drawbar of a 3 tonne trailer at 100Kmh.

This should hopefully answer a few questions.