Thread: I have my MIG all setup, may just need a few pointers...

I don't run a MIG myself but the U groove roller is for Al, the V roller is for steel. Chances are if it was fitted with a U groove roller it has been running Al. If so you should probably change the liner in case there is Al pick up inside which is affecting your feed.

Michael

A grooved roller is used for gas less wire and the V is for steel wire running a shielding gas.

Have you checked the tip? Is it matched to the wire size? And to check wire feed tension, if the wire stalls whilst gripping between finger tips under a medium grip, it needs tightening or a new tip or liner is required.

Originally Posted by mugget

Hi folks,

Well I finally got around to unboxing my MIG and getting it all setup. Started to try and suss things out this arvo.

The machine is a Euromig 140amp I picked up from Greys Online a couple of years ago. I am going to be making up some lightweight frames for a workbench & cupboards, using 30x30x1.6mm SHS and some 3mm flat bar for brackets as required. Using 0.9mm wire and BOC Argoshield Light gas.
Keep your gas flow a little above minimum, should be about 15 litres per minute, anything more is wasted.

I had to battle some wire feed issues at the start, it seemed like the liner would pinch the wire whenever I had the torch at workbench level and then angled it downwards toward the work piece. I raised the machine off the ground so it was closer to the bench level, less of an extreme curve to the line. That seems to have done the trick for now. But I also wonder if I should check the liner or just replace it with a steel liner (being a cheapie I'd guess it has a plastic liner?)
That is the biggest problem with a MIG to keep the line from kinking, I run a 4 metre hand piece, my welder is about .6 metre from the bench, so I know what you're talking about, I set the remote wire feeder just above vise height so that it rests on the bench and does a loop around me. Unfortunately I don't have any room available to move it else where. Blow the liner out with compressed air, when you re assemble it, get a bit of felt to use as a wiper, clamped with a clothes peg, proper parts can be purchased at welding supply shops, this stops dust and other crap getting into the liner. If you're not going to use the welder for a while, put the roll of wire into a plastic bag with the moisture bag that came with it or a 1/4 cup of rice to keep it from rusting. As Michael stated a plastic liner is normally used for aluminium.

I did also tighten the roller tensioner down a bit more, not too much though. I'm trying to run it with the least amount of tension possible to get the job done. Last thing I want is to bust up the tensioner. Maybe I just wasn't using enough tension before?
If the tension is too tight and the wire burns back melting onto the tip, you face the possibility of wire tangling between the roller and the feeder tube, which should be kept about a mm away from the roller.

Next question - it came with the grooved roller installed, and a plain straight V roller spare. Not sure which one is better to use with steel wire? I'm pretty sure that the V roller should be used for steel, the other roller should be used for aluminium. Been a while since I had to change one.

They're the main things I'm wondering about right now, everything else is going fine!
Make sure you use a spray or nozzle dip in the nozzle, to keep spatter at bay in the nozzle.

Cheers for any info!

Kryn

Thanks a bunch for your comments!

There wasn't much info for this welder in the manual/A4 page that came with it, so I was looking up some info online and found that it has 5 power settings, and 10 wire speed settings. I thought it worked the other way around, so things should go even better today! Haha

I will go and pick up some anti-splatter now.

Next question is - how the heck do I change this roller?



The little plastic knob turns to the left, but that just moves a plastic cover over the roller. I think other machines use a spring mechanism? But I can't push or pull this knob - wondering if I need to start unscrewing things? Just thought I'd check if there's a standard way these things usually work, before I get too far into pulling it apart.

The machine is new, so it shouldn't have had any other wire run through it before. Not sure why they shipped it with the U roller installed? I thought it was always a fairly miserable experience trying to run aluminium wire without a spool gun?

Also I think the wire feed tension was a bit low, because I did the grip test & it started slipping. I'll readjust that once I have the V roller installed.

I was going to play with gas flow and ask about that later as well - but I'll set it back to 15 LPM and go from there.

If I recall the one I had, turn to the left the pull the knob out. You can then reverse the wheel or change it.

Cheers DocBug, that is spot on! All sorted now.

Redid the "grip test" on the wire, no problems with wire feed anymore.

Still getting some practice under my belt... but I wonder if I should get a better ground clamp? The one that came with the machine looks pretty cheap, just plated steel and it doesn't have a very strong spring either. Or maybe I'll just try this trick first, get my hands on some copper wire and clamp it between the work piece for better contact?
http://www.weldingtipsandtricks.com/...ng-ground.html

Just wondering about the ground clamp because I'm not really getting that constant "sizzle" type sound, it's more of a random sound. And I've cleaned the steel with a flap disc as well. Anyway I will keep going and see what I can do, will report back later!

Originally Posted by mugget

Just wondering about the ground clamp because I'm not really getting that constant "sizzle" type sound, it's more of a random sound. And I've cleaned the steel with a flap disc as well. Anyway I will keep going and see what I can do, will report back later!

Sounds like you've either got the voltage too high or not enough wire speed

If you're ever worried about the liner, you can pull it out, soak it in kero/thinner, blow it out and put it back in. But when using mild steel wire, you don't really need to worry, can go years in a filthy environment without too much issue. Squirt some graphite powder in there if you want.


Going by the colour of the wire, I'm guessing you're running flux cored aka gasless wire? I don't have much experience with it on bigger machines, I just found the sound was a lot harsher. As long as it's laying a good bead.
If you are running MIG wire, then aside from settings, maybe checking that your gas flow is alright.

Thanks Acco and LordBug. It's all going much better now, had a mate stop by yesterday arvo and give me some pointers. I think the inconsistent sound was a combination of everything - power, wire speed and user input.

Making lots of nice sizzling bacon in the garage now.


Now back to welding tips - when you're joining two pieces to make a 90º angle, should you be able to see some weld penetration on the backside of the steel? For example on the inside of the SHS tube? Or does that mean it's too much, very close to blowing holes? Just asking because I saw one website where weld bead had been deposited onto a sheet of steel, about 5 or 6 rows with increasing power each time. The one in the middle labelled "good" had a definite convex shape on the backside (less that the weld deposit on the front though).

And what is the rule of thumb for the width of the weld you're putting down? Just wide enough so it lets you have a flat or slightly convex fillet?

Originally Posted by mugget

Thanks Acco and LordBug. It's all going much better now, had a mate stop by yesterday arvo and give me some pointers. I think the inconsistent sound was a combination of everything - power, wire speed and user input.

Making lots of nice sizzling bacon in the garage now.


Now back to welding tips - when you're joining two pieces to make a 90º angle, should you be able to see some weld penetration on the backside of the steel?
I doubt that I'd see penetration on 10mm plate . Depending on the material thickness, when you say 2 pieces, is that as in a "T" or a "V"? If a V, welded inside or outside, up to about 3 mm thick, there should be a small bead visible. If a "T" I doubt that it would be visible, but you should see a heated line or bubble looking penetration.
For example on the inside of the SHS tube? Or does that mean it's too much, very close to blowing holes?
Yes, you would be close to blowing through, to get around that problem, move the hand piece a bit faster.
Just asking because I saw one website where weld bead had been deposited onto a sheet of steel, about 5 or 6 rows with increasing power each time. The one in the middle labelled "good" had a definite convex shape on the backside (less that the weld deposit on the front though).
The weld fillet itself, should have a slight convex appearance.
And what is the rule of thumb for the width of the weld you're putting down? Just wide enough so it lets you have a flat or slightly convex fillet?

It would all depend on the size of the parent metal, a 6 mm fillet on 1.6 sheet is an overkill, but you wouldn't put a 3 mm fillet on 15 mm plate. If working to drawings the weld size would be specified, but for yourself, it is hard to describe as I work from experience. Probably for a start I would go about material thickness plus 20%, example 3mm a 4 mm fillet, 5 mm thick a 6mm fillet. Before you start making something, I'd weld a few sample pieces from flat bar and break them apart to judge for yourself the penetration you are getting. Weld them in a position that you will be using, Butt, V, T, etc. one side only. They only need to be about 50 mm long, put one side in a vise and bend them till they break. The thicker the material, the more preparation required, 10 mm plate butt welded, will need Veeing, 45 degrees, on both sides with a 2mm flat in the centre and a gap of approx 2mm, welding each side alternately, to prevent distortion.

Hope this helps.
Kryn

Originally Posted by mugget

And what is the rule of thumb for the width of the weld you're putting down? Just wide enough so it lets you have a flat or slightly convex fillet?

We once had a TA in our workshop welding up some simple frames and he was putting on far too much weld. As one of the welders said to me when I asked how much he should be putting on, he explained (and it's obvious when you think about it) that weld any thicker than the base material is a waste (which you need to try and minimise) as the increased thickness of the weld material won't make the part any stronger (usually it's the parent material next to the weld that is the weakest part).

The proper fillet shape is described in various codes but from memory, it can be flat or slightly convex/ concave. It is more important for the weld to join onto the parent material without undercutting or not fusing with the parent metal. Too convex and I would suspect that the weld has not fused properly with the material underneath and will give you reduced joint strength.

Michael

Thanks Kryn, yes that definitely helped.

And that makes sense Michael. So, you've got to get the weld right the first time around instead of just trying to go back over it and add more metal.

I have started the "break tests" on the scrap 1.6mm RHS I've been practicing on. I think I need to use a higher power setting or use tighter loops to reduce the travel speed?



For this one I turned the power up to 5 (6 is maximum) but it's still not fusing right into the corner. But it is fusing well on the other surfaces, I just can't seem to get the wire right into the corner.

(Still working on an even fillet width the whole length of the weld, I tend to start off thin - but I'm getting there.)

I don't know if it's worth fussing over it for this job (lightweight workbench & cabinets, cupboards etc.), whether it's better to just call it strong enough if it's welded on all sides and move on? Not sure if changing to 0.8mm wire will make much difference (currently using 0.9mm)?

Or if running more wire stick out would help get into the corner? I'm currently aiming to keep it around 6-10mm from the tip (the tip is recessed maybe a couple of millimetres into the nozzle as well), and it does get a bit tricky trying to have a clear view of everything. I know that more stick out would mean a colder weld, so would need higher power setting to compensate.

Practice (experimentation?) will resume tomorrow!

Originally Posted by mugget

So, you've got to get the weld right the first time around instead of just trying to go back over it and add more metal.

That's the basic idea - and it's worth remembering that with some things (welding 1.6mm tube for example) that you will be putting more metal on than strictly necessary just because it's easier that way. A major concern with welding is leaving things in the weld that will cause cracking later on (whether that is slag or weld defects like porosity or poor fusion), so all welding over the top will do is hide them. As a result the weld can still crack - better to do it right the first time. I regarded it as a major milestone when learning to weld not to have to grind out welds and start again. I still do grind, but it's more likely that I'm grinding off a weld because I put something in the wrong place...

A good weld is surprisingly strong, so you may find that welding on say 2 sides is enough for a workbench. The bead on your sample weld there looks a little large but has fused well as you have said. Getting full penetration usually means that you have to have a small gap between the two things being welded - again for a bench, not really necessary.

Michael

Okay, I have welded up just about everything on the frame. Maybe I should have only put weld on two sides of the legs? Or not done each side in a single pass? (They are only 30mm sides though.) Also I had more gap on the top of some legs, which could cause it to bend more? Anyway, those are all things I can think about next time. Now I have a little curvature to overcome:



That's a piece of ally angle resting on top for reference. It's out by 9mm on the left and 7mm on the right.

Just wondering how I should approach this? I know that the metal will contract on the weld side, so should I just weld above or slightly outside the two middle legs on the top to bring it back into square? Or should I try heating the top edge with a torch, then hosing some water on? (I had hoped to keep it dry so I don't have to get it all mucky with lanolin spray etc., but you gotta do what you gotta do.)

I know that backbeading (is that a real term?) will require a lot of grinding, but I may just give that a shot first up.