Completely forget about running 1.0mm wire on your mig, as you will  

• stretch your mig to the max trying to melt it, 
• struggle to maintain a weld on thin sheet without ‘burn through’,
• become frustrated at not being able to use 1.0mm & give up altogether!

Trev,

Sir, I didn’t realise you hadn’t previously used your MIG welding machine to produce satisfactory welds.

I am a skilled welder & have got some bad habits, such as ‘making do’ with the wire size that I have in my wire feed unit at any particular time, rather than change to ‘the perfect set up’ for every single job or bodywork situation.

I personally prefer to use 0.6 dia solid wire on car bodywork for the following reasons:

Rust & paint is always cleaned off the surface first, without ‘thinning’ the steel, (I don’t use grinding discs!) but it does not always leave perfect pit free steel, & the ‘weld energy’ using 0.6mm wire suits my weld quality requirements perfectly as regards penetration & weld bead profile.

Especially suitable on thin 0.8mm thick panels!

When I come across a very thin part of a panel, or panel edge, & accidentally cause a ‘burn through’, I am able to very quickly use ‘back step’ or ‘stitch up’ techniques & procedures to immediately repair the damage or hole, & continue welding without having to stop or have another ‘repair procedure’ put into action in order to complete the weld.

This is not always easy while using 0.8mm wire, as obviously you are welding at slightly higher amperages & the very edge of a hole may not be quite so tolerant to 50amps as it is to 40amps.
 
There is nothing worse than blowing a hole near a panel edge or ‘thin bit’ & then having to mess about stitching it back together to fill the hole, & ending up with an unsightly lump of weld metal to ‘dress back’ to ‘acceptable appearance’, as I have professional standards that I do not deviate from!
'Chasing’ a hole for an inch or so, is just not on.

However, for the purpose of your sanity & patience, & mine, & considering your capabilities, I think you may be better learning MIG welding by starting on heavier 0.8mm solid mig wire & then move down to 0.6mm when you feel more confident.

All the car bodywork that I encounter is usually attached to an ‘older’ vehicle that needs major panel work replacement & repair, but this doesn’t mean that 0.8mm wire can’t be used.

We are talking about what’s known as ‘short circuit weld transfer’ here, primarily because as the solid MIG wire hits the weld pool, it ‘short circuits’ the electric welding circuit that you are

creating between your welding power source (open circuit until the MIG torch trigger is pressed) & the weld pool on the job you are welding.

As the short circuit occurs, the wire melts back to create an open circuit, & a droplet of molten wire is propelled into the weld pool via the ‘weld plasma’, (across the arc) but considering that the wire is continuously fed, this is obviously a ‘forced situation’ & the process is repeated many times per second (up to 60 in this example).

So in reality, when you press the torch trigger & start to weld, you are depositing a fast ‘stream’ of weld droplets & the ‘crackle’ that you are hearing is the electric arc transition from open circuit to short circuit.

Right Trevor lets get started on the settings….

On new or old 0.8mm thick regular panels, select about 55amps to start with, this is far too high for a ‘but weld’, but fine for a close fitting ‘spot weld’ or ‘tight plug weld & even a vertical down ‘close fit lap weld’.

You have to start somewhere with amp settings, so I always go too high, try a run & I nearly always have to trim down the amps to suit the wire feed speed.

I normally select the wire feed speed at various ‘known settings’ on my different MIG welding machines, but this is actually around 95 inches per minute (ipm).

(But more usually I will set the wire feed speed at 80ipm & work from there, adjusting the amps up or down to suit the wire, as I know my machine parameters pretty well)

I can hear you saying that your MIG welding machine has no readable settings outputs, just dials & switches!

Don’t worry Trev, my machines don’t have digital panel meters either, as I will not pay for fancy ‘bells & whistles’ unless vital for a specific application!

So, to recap on the ‘start-up’ settings for 0.8mm wire, set your machine to supply 55amps of welding power. (suitable for thin 0.8 panels)

Turn your wire feed speed control so that you will get far too much wire delivered when you press the trigger!

Ensure that your ‘argon mix’ shielding gas has purged through your machine & MIG torch & that the delivery pressure is set to at least 10ltmin, & that you have no draughts at your ‘practice joint’.

If your Argon gauge is not selectable for delivery pressure, you only need to know that gas is actually coming out of the welding torch bezel sufficiently to exclude atmosphere from the weld area (specifically the ‘weld pool’), you are not looking for masses of gas like an airline blowing up a tyre!

Find some scrap steel that is at least 3mm thick, that’s right 3mm thick. (call it your practice plate)

Grind  a clean line down the 3mm practice plate/angle iron/whatever, & do a quick short weld run in the flat position.

• Did the wire just fly out of the MIG torch & glow red instead of melting?
• Good, now just reduce the wire feed speed by a TINY amount & do another test weld.
• Same result again?
• Good, reduce the wire feed speed again.

Do another test weld & analyse the result.

Reduce the wire feed speed again by a TINY amount.

Do another test weld on your practice plate & analyse the result.

You are always looking to produce a satisfactory weld at a set amperage to suit a given wire diameter & steel thickness.

What you are doing here is starting at a known (previously defined & proven) good amperage for 0.8mm wire & 0.8 thick steel sheet (55amps), & now you are doing test welds to ascertain if the wire feed speed is too fast, or too slow. (always start too high & trim down).

So, keep trimming the wire feed speed down until you can produce a good clean weld with out the weld bead being too pronounced (overly heavy weld metal deposition).

It is without doubt that you will find the point where you have the perfect wire feed speed at this amperage, & because you are using a 3mm thick ‘practice plate’ you will not have a line of ‘burn holes’ to look at, as you would ‘practicing’ on 0.8mm thin sheet!

You will also now recognise the sound of the sharp, crisp, weld crackle noise, as this is a good indicator that you have arrived at the optimum short circuit setting at your selected amps.

You are now ready to transfer your ‘practice plate’ settings to the same material as the job that you want to weld up.

But, patience must persevere, so it is still practice time for the moment!

Now do the exact same procedure on thinner sheet steel.

Don’t change the amps yet!

• Try a quick ‘flat position weld run’ on a bit of new panel work (or scrap/offcut sheet) that has another bit of sheet lying flat on top of it so that you are producing a ‘lap weld’.

(Your ‘panel practice joint’ should be clean of rust, paint etc & they must be a close fit with no big gaps between them).

• Does your test weld go reasonable without burn holes?
• Are you aiming the weld pool at the joint correctly? Don’t aim it directly on the base panel, as you will burn holes, same goes for the top plate.
• Instead, allow the ‘weld energy’ to use the thickest, heaviest or largest part of the joint as a ‘heat sink’ to absorb the arc heat & dissipate it without overheating any one part of the joint.

• Therefore, you should, in this instance, be aiming the arc at the centre of the joint to start with.

Practice on heavier material first if you have too, but you must grasp the fundamental elements of starting from known amperage values, setting wire feed speed too high, then trimming down the wire feed speed until you find the optimum weld parameters.

It is then much easier to use & apply the weld settings to any thickness of material, as you literally have a working example in front of you, & it really is straightforward to make MINOR

adjustments to the wire feed speed first, to ascertain suitability as regards penetration or deposition etc, BEFORE you start adjusting the amperage up or down & then restarting the systematic wire feed speed adjustment.   

Incidentally, Trevor, if you do have a voltmeter on your MIG welder front panel, & I have just explained all this for nothing, please set it to provide 15.5 welding volts, give or take ½ a volt, as the welding volts are essentially controlled by the wire feed adjustment (just to confuse you further!) & are directly relevant to the amperage you have selected (55) in order for you to get the optimum weld setting parameters every time!

& while we are on the subject of confusion, when you go to your welding products supplier to purchase 0.8mm solid mig wire, specify a ER70S-6 grade wire, as the deoxidisers & silicon are beneficial for old car bodywork & it gives a nice ‘fluid’ weld puddle, with great weld bead appearance.

The more regular ER70S-3 grade is a tiny bit cheaper, & is also suitable for all positions, but I personally find that the weld puddle is a bit on the ‘stiff’ side for body work.

Your Argoshield Light (BOC gas trade name) shielding gas is fine for these wires.

& just to make your MIG welding life a bit easier with car body work intricacies, nooks, crannies, & internal corners; try this:

• Cut the end of your MIG welding torch bezel down so that your copper contact tip is sticking out past the bezel by about 8mm.
• Your solid MIG welding wire should have a ‘stick out’ length of approximately 6mm at the settings you arrived at using all of the above set up procedures for 55amps.

This is sometimes hard to maintain if your machine has ‘burn back control’ which I don’t think it has, but these manual values are a good guide to use.

• Sometimes a beginner will be better with 8-10mm ‘stick out’ & will rapidly learn to control the optimum parameters that allow fast & continuous welding without any stoppages, such as ‘birds nesting’ of the wire feed rollers, which can be caused by various poor settings.

If you have correctly set your weld parameters but are having continuous ‘burn backs’ which cause your mig wire to become melted onto your copper contact tip, check these next things first before condemning the settings that you can now expertly & quickly arrive at:

• It is vital that you can test & eliminate causes of problems systematically & immediately without specialist electrical test gear or otherwise!
• Before you even start to swear at your MIG welder, double check that you didn’t just accidentally bump the wire feed control! (I am guilty of this!)
• You can do a quick test weld after each step in order to isolate any potential problem, but complete all steps to rapidly identify any weakness, especially in the welding circuit, but not inside your MIG welding machine mains voltage control panels or transformer housing!   

These things may look obvious at first glance, but this ‘markthewelder mig checklist’ solves 99% of welding problems, after first arriving at correct weld parameters.

• Immediately after burn back occurs, touch the end of the contact tip lightly with your angle grinder (if the MIG wire has bonded to the end of the tip),in order to reveal fresh wire & give the torch a quick rotational twist to see if the wire will release from the tip.
• You can do this hundreds of times if required, before the contact tip becomes unusable, my welder trainees are testimony to this!
• If no voluntary wire release, slacken off wire feed roller tension to allow free movement of mig wire (& leave it slack for the moment).
• If no voluntary release, remove tip & replace with a fresh one, as you will not have burn backs in the future!

(Some welders use 0.8 tips for 0.6 wire & 1.0 tips for 0.8 wire & 1.2 tips for 1.0 wire) (just a tip!)

• If MIG wire has ‘fused back’ inside tip & is not visible, do above.
• When cutting MIG wire, use good side cutters that don’t flatten or splay the end of the wire, as you want the wire to maintain a round shape so that it feeds back through the torch liner at the torch neck, & cleanly through the contact tip without fouling.
• Ensure tip is gently tightened with pliers or spanner; as just ‘finger tight’ can cause high electrical resistance.
• Slacken torch mount at machine front panel or remote wire feed unit (do this for euro torches especially)
• While this is slackened, pull torch connector slightly away from machine & check tightness of gland nut that secures the torch liner inside the torch flexible cable.
• Re-attach & tighten torch body.

Moving to the MIG wire feed rollers,

• first check that the central wire spool carrier has just enough pre-set tension to stop the spool from ‘freewheeling’ & allowing the wire to unroll or become displaced.
• Double check that the drive wheel (or wheels if you have a four roller unit) is the correct way around to suit the wire, as the wire diameter rating is etched onto the opposite side of the roller to the corresponding correct groove. This is so that the installed drive wheel drives the wire via the inboard most groove, but the diameter rating is visible from the outside of the machine! (strange but true!)
• Then check that the idler wheel (the plain one with no groove) is free to turn on its bearing or spindle & has no foreign matter stuck to its working surface (this is often missed).

If your MIG wire leads from the spool & through a nylon ‘leader tube’ via a plastic leader sleeve,

• check that the wire has not worn through the leader sleeve to the extent that the sleeve has gone thin at the tube end.

This can allow the sleeve to move too far inside the leader tube & foul the MIG wire or cause the wire to misalign onto the drive roller when drawn from the spool.

• If it is grooved at the tube leader end, cut it back to full thickness or just reverse it on the wire & re-insert into the leader tube.

If you temporarily re-tension the wire feed rollers, you should be able to see that the wire is perfectly aligned centrally at the lead in tube (from the spool) & at the torch leader (normally brass tube or similar).

If you suspect side friction on the wire, or any other misalignment problem, rectify it now.

(Check of course, that the rollers are correctly assembled & the wire is in the correct groove properly).

Ok? Now that you have eliminated problems at the machine end,

• manually feed the MIG wire from the spool, through the feed rollers & up through the torch liner & through the contact tip.
• If it went no problem, great.
• If the wire would not pass from the torch liner into the contact tip, ascertain that you have cut a ‘reasonable’ end on the mig wire by pulling the wire back out of the torch using the spool & trying a new tip over the end of the wire.
• If the tip fails to fit, fix the problem now.

If the wire fits through the tip, but fails to pass from the torch liner into the contact tip,

• remove the liner from the torch & examine the cut end of the liner (all good torches are user serviceable).

The torch liner is made from plastic coated coiled spring steel, much the same as an old type ‘net curtain’ wire.

The ends are difficult to cut perfectly square, & this is what normally causes the wire to misalign at the contact tip, or be cut so that the wire struggles to pass through centrally. & yes they leave the factory like this!

• Use your angle grinder with a ‘flap disc’ to gently polish the liner end barb back to a flat profile, hence allowing the liner to fit perfectly in the brass torch socket at the neck
• & do the same at the liner access gland nut if required.

Now that your MIG wire has an optimum feed path,

• manually feed it through again, this time it will pass through the contact tip perfectly,
• if it doesn’t, look again at your wire cutters before starting to swear at your MIG welding machine.

This ‘liner adjustment’ also applies to Teflon coated liners, & is especially beneficial to users of aluminium MIG wire, as the tiniest bit of ‘wayward end barb’ on the liner can ‘scratch into’ the aluminium wire & cause endless ‘birds nests’.

An easy way to check for a suspect cause of the liner end problem, without dismantling, is to disconnect the ground clamp welding circuit cable, press the torch trigger & bend the torch backwards, sideways etc as the wire is feeding through. If a foul up occurs all by its self, you have just found yet another cause of wire feeding problem.

A visual way is to remove the contact tip, feed the wire through & look for evidence of scratching on the wire, this does not apply to mild steel solid wires, but flux cored MIG wire driven by really sharp grooved drive rolls suffers from easy foul ups, as the small nicks from the ‘wheel footprint’ on this tubular wire are just asking to be snagged! (Especially if the drive rolls are not set spot on)

Now that the MIG wire feeds through everything feely, it is time to restrict it by tensioning the feed rollers correctly.

I have read about, seen, tried & tested lots of variations with all kinds of MIG welding wires, & here’s what works with solid wire:

• Assemble feed rolls & back off tension,
• feed enough wire through the contact tip so that you are able to grip the wire with pliers or similar.
• Increase tension on the drive rolls until you are not able to easily pull the wire through the torch.

It is as simple as that, in my opinion.

You are aiming to have the wire tensioned between the rollers enough so that it cannot slip if it meets slight resistance, & you will soon realise the complexities of that statement should you be unfortunate enough to have burn backs, birds nests or other wire feed calamities that I will endeavour to help you avoid in the first place!

This gets a bit more complex when using tubular flux cored wires running through four wheel drive serrated drive wheel systems, but in the main I never have high tension applied, as crushed wire is a definite situation to avoid at all costs.

& if you apply the same principles to aluminium MIG welding wire, you will not have any wire feeder problems.

I should have mentioned this earlier,... but while messing about with spools of MIG wire, you will find that a small pair of Vise Grips (the kind made in the USA) are absolutely essential to prevent your MIG wire from defiantly escaping from the reel, due to the effects of the way it is coiled onto the spool.

Always clamp the grips onto a loose wire end to save a major disaster.

You will only accidentally create a mig wire 'birds nest' once, & you will remember the Vise Grips forever!

Cutting back the wire that you have damaged with the grips is not half as bad as rewinding or untangling a big wire spool!

& while on the subject of dodgy MIG wire, avoid ‘cheapest brands’ that have no manufacturer’s production labels!

Yes, I have tried them out of curiosity, No, I will never use them again! Period.

Further to MIG wire quality, it is actually made to very stringent standards.

Apart from the complex chemical compositions, that I will mention later, the wire auto unwinds due to the ‘cast’ properties, which is the diameter of the wire after cutting a length of 3 metres  & placing it on a flat surface, then measuring the diameter of it as it rests freely on the floor.

Try this yourself, & you will also see that a part of the coil will be raised off the floor by approximately 24mm at the highest point, & this is called the ‘helix’ properties of MIG welding wire.

For example; 1.0mm wire should have a minimum ‘cast’ diameter of about 370mm.

While these references may seem non relevant to a MIG welder, I have seen cheap MIG wire cause all sorts of welding problems, as the wire exits the contact tip but does not feed perfectly straight into the weld pool.

Again, strange but true,  & covered in depth by AWS standards.
 

Purely for your benefit, this is mostly noticeable when using oversize contact tips & training MIG welders to produce heavy spray transfer welds on precision butts etc, but you wouldn’t be using oversize tips in the first place, would you?

OK  Trev....

just check that the MIG wire drive feed rolls are tensioned spot on, & you should be in business with pretty much all bases covered.
 

There are lots of other technicalities that are very worthy of mention for your continued MIG welding success, but I will wait until you get going before preaching any more topics!

Should you have any further questions, please just ask.

PS any feedback or comments is always welcome, negative positive or otherwise.