Welders and Welding

In my time honoured way of learning to do stuff I'm approaching something
completely blind.

I have acquired yet another VW camper ('78 Danbury Bay) and - surprise,
surprise - it needs some welding.

I had prepared all the plates and chassis but the mate who was going to do
the welding is off to Croatia until January but has kindly left me his
welder to get on with it: "It's like a hot glue gun; don't break it".

All simple enough except I have no instructions. Plenty of scrap steel
though.

It's a good quality welder with a very large bottle of Argon mix gas.

What should I set it at to start practicing on the 2-3mm steel plate
offcuts and square section tube I have?

Three knobs - I assume feed speed, electricityish and something
staircasey:

http://www.sweller.dynalias.org/images/welder.jpg

Gas pressure?

Tips, tricks and traps?

I'm getting an automatic mask as I'll have enough to contend with.

 

If the repair work needed is extensive, then its going to be a nightmare for
a beginner. As to setting up machine, try and get an instruction sheet that
tells you what the controls do, and then practice as much as possible on
thin sheet steel, in downhand position, and when you can do that ok, more
practice positional and overhead.

k

 

Work isn't too bad - couple of plates and an outrigger - VWs are very
simple things.

I have to say, if I had an instruction sheet I wouldn't be asking...

 

I'm not a welder and the only welding I've done with mig has been
after someone else had set the machine up so anything I suggest about
your machine would be guesswork.

What I would suggest is that you get some scrap section in the same
condition as the bodywork on your VW and practise on that. Practising
on heavier gauge steel that isn't falling apart might be fun but it'll
do you no good when you have to get the job right. The other advise is
really obvious and that's to keep the feed rate and amps as low as
possible or you'll blow everything apart.

Have fun.

 

If your amps are too low, you will get no penetration, you will just
blob loose metal on the job. If your feed is too low, the wire will
melt back and jam, if too high it will put out too much wire which will
burn red hot and coil up.
Try to practice on heavier steel. Turn the MIG onto a mid range and get
someone to vary the speed so you see what too slow and too fast does,
you want a steady crackle and to move the gun slowly along the steel
keeping the puddle of molten metal moving along the job.
Remember, pausing gives more heat and blows through the metal (or
builds a pile if the metal is thick) and going quickly gives less heat
but too quick will not penetrate.
When you think you are ready, practice on a similar thickness metal,
before the real job. Another way, is if you can back the job with spare
metal to stop you blowing the job away.
I take it you are not in the NE?

 

Wire feed speed, yep. I'm wondering if the staircasey bit is the power
(would make sense) and the 'electri-ish' setting is actually an interval
switch, which would explain why it's set to '0' so you get a continuous
flow of current as long as you press the trigger.

It's a 210 amp machine which should penetrate well enough for 3-4mm steel
IIRC. I'd leave it on a middle setting (like '4' on the staircase) and
would try to stick two plates of the required thickness together. You tend
to start doing that by blowing holes into them

Dunno, I pretty much cranked it up most of the way. Depends a bit on the
conditions (you need a lot more gas if you're trying to weld outside as the
wind blows it away). Gas is fairly cheap compared to leaving the front axle
behind so I tended to err on the side of caution.

It's not that hard, even I managed to become pretty proficient with a MIG a
while back. The trick is to achieve proper penetration of the material - on
the 1mm steel I was shown to weld two strips of metal on top of each other
just using spot welds - if you tear the strips apart afterwards, the weld
shouldn't break but rip a hole out of one of the strips.

Once you get the wire speed right (so the wire neither hits the metal while
you're welding nor burns back into the gun) I found it easiest to 'push'
the pool of molten metal from right to left making a very small circular
motion with the nozzle/wire. Bit like drawing a succession of small circles
with a pen. If you're left-handed you obviously should reverse the
direction.

The correct sound when welding is a 'sizzle', usually described like frying
bacon. If you get a lot of spatter there's either not enough gas or some
contamination on/in the material. You really want to clean the material up
properly and not try to stick new metal to rust as the latter tends to
result in pretty crap welds.

Oh, and turn the gas off afterwards if you're done...

Smart move. And wear something (a) long sleeved and (b) made from 100%
cotton so the spatter burns right through instead of melting the fabric to
your skin. Long sleeved because it's a good way to achieve a proper sunburn
otherwise.

 

chippy says...

<Schoolboy mode>

Huhuh, he said "penetration"

</Sm>

 

From an amateur (but expert at pigeon-shit welding):

Preparation is imporant for MIG welding.

Make sure the metal to be welded is clean - MIG is not very tolerant
of rusty or dirty metal. It'll spit and stutter and spatter burning
shit everywhere.

More gas = better shielding but costs money. Once everything else is
set up you can always back it off a bit.

Be sure to cut rusty panels right back to good metal. Thin steel will
burn through and you'll end up trying to blob over holes you've burned
in the steel. And then you'll end up trying to blob ove the hole you
made trying to blob over...

Don't try to weld outdoors unless it's flat calm becuase the wind will
carry away the shielding gas. Symptoms of insufficient shield are
rough scaly welds with blowholes. The welding tends to spark and
spatter more, too.

If you weld underneath, wear head protection and even ear protection.
You wouldn't believe how much a piece of burning spatter hurts as it
sizzles through an eardrum. DAMHIKIJD, OK?

 

I have repaired lots of campers in the past, and most are very rusty and not
at all easy to repair properly!

The reason for suggesting you got hold of an instruction sheet for the
welder, was so that you could be certain of what the various controls
actually do, but if you dont want good advice I cant understand why you
bothered to ask.

k

 

Do some research. There's a considerable amount about on the web.

1/3 up from zero - 3 out of 10 if you like, on both current and feed
speed. Step by step, run by run, increase one then the other until
you can perform a nice clean, straight run that doesn't stand up like
an old sleeping policeman, but lays into the work like a modern speed
cushion road hump.

Then cut your first joints through to check for penetration. Once you
have it right you will get the feel and the sound (like frying bacon,
as Timo said) and then you'll be flying.

The top control is wire feed speed. The control below that is for
spot welding and should be left at zero. The 'staircase' is the
control that sets the welding current, in a series of coarse steps.
Fine current control is adjusted semi-automagically by the wire feed
speed control, increasing current as feed speed is increased.

Should be set by the regulator and won't need to be adjusted - the
turning off the gas wheel is separate.

Always wear full PE. Always.

Gauntlets are a given, as is the mask. Good quality overalls with
sleeves tucked into the gauntlets. Cotton Tshirt under the overalls.

Try to position yourself comfortably and rehearse your welding run
before flicking the switch.

Only ever attempt to weld clean, clean steel. Corrosion wil vapourise
and come back to haunt you as a fine, molten mist. Best way to clean
existing body metal is by use of an angle grinder. Shiny steel is a
must, as is a tight fit before welding - trying to bridge gaps will
cause an edge to melt.

Clamp everything up before welding it. The wire will push it about,
otherwise. Never rely on holding work, it gets very hot very fast.
Mole grips are very good for this sort of thing.

'Push' the weld pool in front of the torch, not trailing behind it.
Learn to love your weld pool and keep at least one eye on it at all
times. Make sure it is melting both sides of the joint evenly and you
aren't wandering off line.

Don't try to seam weld everything straight away. Tack it in first,
one dot every few inches; then you can go back and extend the tacks at
a higher current. Keep runs down to an inch or two, then move along
the joint a bit to let the first bit cool a little before going back
to it. For MOT, all joints must be seam welded now. Build up your
seams, but beware heat distortion.

Avoid any welding that is not downhand (you above the work, looking
and working vertically down onto it) to start with. Vertical and
overhead welding are separate skills and take some learning. When
going vertical, start from the bottom and work up. I usually build up
a little 'ledge' of molten metal and persuade it uphill.

For inverted or overhead welding, reduce the current by one step. Do
not lie directly beneath the line of welding - work from the side.

Try not to get in the way of the molten metal spraying about, and
check yourself frequently for burning bits.

Don't ever *ever* look down the torch and press the trigger - the wire
will zip out and pierce your eyeball.

Have a fire extinguisher /and/ a bucket of water (I have a trigger
spray filled with water too) to hand at all times.

Treat all metal welded as red hot until you are *sure* it isn't.

Arc sunburn is a bitch, especially to the retinas.

Practice makes perfect.

Remember to breathe.

Relaaax.

You may find it easier, once you have set the shade level (how dark
the screen gets), but I can't get on with mine except when welding
outdoors.

HTH.

 

He probably didn't want it from a **** like you.

 

I have forgotten more about welding than most here will ever
know...................Perhaps you would be good enough to tell him exactly
what the controls on the welder do?

k

 

I wonder if this **** can advise the OP on how to turn his VW camper upside
down, so he can do the welding work without having to weld overhead?

k

 

If you plunge a hot object briefly into cold water it will be cool enough
to hold but it won't stay cool for very long.

 

You've forgotten ?

 

No

 

A /lot/ of good advice, especially from TImo
covering many safety issues.

One thing not mentiond so far is the utility of long
clamps like these:-

Warning unsuitable for children - TOOL PR0N
http://buy1.snapon.com/catalog/item.asp?item_ID=51310&group_ID=13185


I have done a lot of gas welding on scrap heaps.
The issues will be different I am sure but the
thing that was most challanging was the way that the
metal often moved apart as it heated up and expanded.

There is much less heat used in MIG so maybe the
issue has gone away to some extent.

Remember that the holes that you drill for
the temporary self tappers/rivets to hold all the stuff in
place can be easily filled with weld

Sometimes you just NEED a fireman to keep an
eye on the inside when you are underneath.

I know it has been said already but don't even
start without a fire bucket and squirty bottle.
Your house insurance co. will thank you.

I think that you will be surprised how clean the
workpieces have to be. I suspect MIG will be quite like
brazing or soldering in that respect.

Worst /ever/ welding experience.
[Luckilly I have never set one on fire and
burned the street down]

Rusty Morris 1000 traveller.
For some reason car just did not like me, spitting and
popping red hot metal at me from pretty much wherever
the torch went. Never seen anything quite like it.
Eventually came to conclusion that car had probably
been plated with copper as a side effect of cuprinol
treatment, Anyone who has ever tried to weld steel
that has been brazed will know what I am talking
about.

 

Given that you've forgotten more about - pretty much anything under
the sun, if your posts are to be believed - than most here will ever
know, then you must be *fucking* forgetful.

 

Pip Luscher says...

I'd wager he never knew much in the first place, cos he knows **** all
now.

 

Heh, I mig welded the chassis of one of those, in my back garden, using the
drain manhole as a "pit", in the pouring rain, under a tarp.

Still have the scars up my arms to prove it.

Passed it's MOT 1st time afterwards, mind.

--
Dan L (Oldbloke)

My bike 1996 Kawasaki ZR1100 Zephyr
Space in shed where NSR125 used to be
Spare Bike 1990 Suzuki TS50X (Patio Ornament)
BOTAFOT #140 (KotL 2005/6), X-FOT#000, DIAABTCOD #26, BOMB#18 (slow), OMF#11