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Discussion Starter · #1 ·
I've only been doing this about a year, so others may be able to expand on what I write here. The basics of MiG welding can be learned literally in minutes, everything else is practice and refinement.

First topic is selecting your welding machine.

Voltage: First and most important is making sure you can plug it into your electrical outlets. Machines are available from 110-660 3 phase (more on 3 phase later).
The higher voltage it uses the heavier material you can weld, for things like exhaust/body work a 110 machine will be sufficient. For heavier material, (as much as 1/2 inch, depending on prep and final product) 220 will be sufficient. Unless your doing commercial/industrial work higher than 220 is not needed.

Note on 3 phase: Unbeknownst to many electricity can be/is sent through the wire to your house on three frequencies. (i forget the freqs at the moment, but it's not important) A three phase machine requires a special transformer and outlets (220 3 phase won't work off you drier plug). The main benefit to a three phase machine is that when introduced to the machine correctly it can help to turn electric motors. A 3 phase machine will be stronger and more efficient than a similar voltage machine, but it WILL use more electricity. You will also have to call an electrician to get 3 phase service installed.

Duty cycle: This is listed in percentages, most 110 units will have a 10% duty cycle, meaning you can hold the trigger down for ten minutes out of an hour. Heavier duty machine (higher voltage/3 phase) will have a longer duty cycle. For someone who won't be using it much and certainly isn't using it for making money 10-20% should be sufficient.

Wire: Next is should you use gas or flux core wire?
Flux-core wire is self defining, there is flux in the center of the wire which burns away when you weld, creating the shielding gas you need for welding. This is best used for machines that must be highly portable.
Standard MiG wire contains no flux, and you must use a compressed gas that released at the same time as the wire to create your shielding gas, I find this leads to better welds, personally.
Also a concern is what size wire to use, and this will depend on what thickness material you will be welding. The thicker the material you are welding the thicker wire you will need (I use .035-.045 for welding 5/8).
You can later change to a thicker or thinner wire but you will need a new set of drive wheel for your machine and a new welding tip.

What brand?
Miller is still the cadillac of welders, but I would recommend a Systematics welding machine (don't bother looking, they don't have a website). They have excellent service and low prices (you can sometimes get machines that were never picked up for a song). Not only that but they are Snap-On welders. Not equivalents, they ARE snap on welders. Literally the only difference is a sticker (and about half the cost). They are located in SE PA.

Section II: What kind of gas?

For welding steel a 98%/2% mix of Argon/CO2 is best (and mandatory for structural work). This will give you a better shield and more penetration.
Many shops (including mine) instead use a 75%-25% mix, since it's much cheaper and almost as good.

If you have purchased an Aluminum Spool gun for your welder (works great, but not as pretty as Tig) you will need straight Argon.

Note: DO NOT buy/lease a tank for your welding gas. It is not only not necessary but a pain.

Many welding gas suppliers won't fill tanks that you own/lease, either because you bought it from someone else, or because they want documentation that you own it.
You will also need to get it pressured checked every 1-10 years depending on the test that is done.
Renting is cheap and much easier. Plus when you need a new bottle they'll drop off a full one and pick up the old one.
Only buy one if you're gonna be doing very little welding. If you want to be sure the tank is still good check the stamped markings at the top of the bottle. Find the most recent marking (last two digits of the year checked). If it's more than ten years ago you _must_ get it pressure checked and certified. If not, a + will indicate that the test is good for five years from the date stamped, a Star will indicate ten years.

Section Three: Machine setup.

First is to connect everything (of course).

First you'll connect your gas bottle (if you have one). Secure your bottle BEFORE removing the protective cap.
*****A NOTE ON BOTTLE SAFETY*****
Welding gases are under VERY HIGH PRESSURE. If it falls over and you knock off the valve there is enough pressure to send it through a cinder block wall, more than enough to seriously injure or KILL you.

If you've gone with a small machine either use a swinging latch with a bolt or chain to secure it to the wall, or a table that has been attached to the floor.
If you're using a larger machine machine there will likely be a bottle holder on your machine, make sure to chain as tightly as you can.
Now is to tighten on your regulator to the bottle, and then the gas line to the regulator. You do not need a bottle wrench, a 12 inch adjustable wrench is just as good, if not better.

Next is your ground wire and your trigger (the Trigger is also called a Stinger).
Now, your machine will be marked positive and negative. Which goes where,? check your documentation. Some machines you plug them in backwards (ground into the positive). Some machines are marked properly (ground into the negative.) So you'll have to read.

Next is installing your welding wire. Be very careful when unwrapping your welding wire, if it starts to uncoil it will all uncoil and you'll be very unhappy.
First, unhook the end of your wire from the it'll be threaded through the side somewhere. Cut off the end so you have a nice clean straight end. I like to tape it down until you're ready for it.
Second, place your wire on the holder, you'll have to remove the clip first (the spool is usually held on by a C clip or something similar.
Now that your wire is secured take a look at your drive wheels. The upper drive wheel will move out of the way, most likely with a spring loaded knob. jut pull slightly and swing out of the way.
Third, Untape your wire wire and thread it through your drive wheels, there will be a short tube before you get to the drive wheels. once past the drive wheels you insert the wire into the end of the stinger line. at this point you can resecure the drive wheels.
Fourth, if your machine isn't already plugged in, plug it in now, turn your wire speed up and press the trigger until the wire comes out the end of the stinger.
 

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Discussion Starter · #2 ·
Section Four: Setting up your stinger

If it isn't already attach your welding tip. Then twist on the nozzle. In the end you're gonna want you tip to be about 1/4" from your material, but the you can adjust the nozzle to where you want it. the tip doesn't have to be flush with the nozzle, I like to have the tip slightly inside the nozzle.

Section Five: Am I ready to weld yet? No.

Setting Your gas pressure:
Now you need to set you're gas pressure. Turn on your bottle (one turn forward then one quarter turn back should be sufficient sufficient). Now to adjust your pressure, turn the knob on the regulator. You have the correct pressure when the regulator reads around fifty. To get the reading you can either press the trigger or the 'purge' button on your welder.

*****Welding Gases Safety Note*****
Welding Gas isn't exactly good for you, make sure you have good ventilation (not a fan, it will blow the gases away), or use a mask if you wish.

Setting your Voltage:
The correct voltage will depend upon the thickness of your material, I generally like to go with something that is as hot as possible without burning through the metal, so you'll need to do some testing, but 1/4" or thicker you can crank it pretty high. Some machines are labeled in steps (1,2,3,4) instead of voltage levels, the same method applies, though some may have a list stickered on it somewhere for recommended voltage levels.

Setting your Wire Speed.

If you have a machine that labeled in steps set your wire to the same step to start. If not, then set your wire so that the knob is turned about the same amount as your voltage knob. to start with.
Now that you've got something to to go on start a weld pool, either on your steel table or a piece of scrap material. Now you have to listen. If your speed is correct it will sound like sizzling bacon. If you get a snapping sound your speed is too high. If there's a hissing sound and/or you see bits of wire dropping into the weld pool the speed is too low. Adjust until you get the right sound.

Section Six: Prep.

How much prep you do will depend on your machine, material thickness, purpose (structural or not) and, anal retentiveness.
Step one: Grinding
Remove any paint or mill scale. You don't have to remove the paint,if you'd like simply get your wire hot, and press it into the paint, then move a little slower and use the weld pool to burn it off. Mill scale, also doesn't really need to be grinded off.
Step two: V-ing. If you deem it necessary use your grinder to put an angle on either side of two pieces of material to be joined to get better penetration.
Step three: Preheating. This can be used to give both better penetration and prevent warpage.

Section Seven: Welding (Finally)

First hold the stinger in your dominant hand so that you're comfortable, and if you can rest your other elbow on the table (or whatever) and hold the nozzle. It's important that you be comfortable for the best welds.
Now that you are ready and comfortable it's time to practice.

Just run a bead.

Looks horrible huh? Figured.

I can help. Make sure you move your stinger evenly. The best welds generally look like a stack of nickles that's laying over, though MiG welds will be much more uniform looking. and be pretty much smooth. The sides should not be curled over. Which means on either side side of your weld, if it lloks like there's a bit of crevice there your not getting much penetration, it should flow smoothly into your base metal. Practice running beads forward and backward and down and in corners.
When welding vertically you should never move the stinger upwards, you'll get big globs of weld and burn through, and it's just not good. If you move down it's pretty darn easy to get a good weld.

Tomorrow I will post different methods for running your beads, and an FAQ.
 

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Where i worked we had to do 13 foot beads in one bead whip welding with 1 inch thick steel lol (military equipment) Now thats something to practice!
 

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Nice!!! I think this will help out alot of people on the site!
 

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Discussion Starter · #6 ·
Another safety tip, wear all cotton clothing. Poly anything contains plastics and can melt to your skin when hit by the welding sparks (and it will get hit).

Also remember your safety glasses when grinding, I've gotten steel in my eye and it is not pleasant, nor is getting it removed.

Oh, and I actually was wearing the glasses at the time, so be careful either way.
 

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Discussion Starter · #7 ·
Different beads and general welding technique:

There are several different ways to actually run the bead, none times out of ten a simple straight run is just fine, but if it's not you can...

'C' bead

While moving forward move the weld pool back and forth over both pieces of material. Good for heavy materials.

'Back and forth' bead

Lay your bead and every few 1/8s of an inch bring the pool back over what you just welded. Useless in my book, it's just laying weld on weld, with little or no extra penetration, and it contaminates your bead.

'Forward/backward' bead

In this case you run the bead in the opposite direction you're going overall.
thus if you're welding the piece left to right, then you would run short (a few inches) beads right to left. This is excellent for preventing warpage in thinner materials.

More later tonight, possibly tomorrow.

Thanks for the compliments, I hope it helps some people do some DIY.
 

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Another tip is be carefull with the setting of the auto-darkening helmet/choice of lens for the non-auto darkening-flip down helmet.

I personally outline the lines of where I'm about to weld using chalk. Just simple white chalk. The stuff you can get pretty much anywhere, at any craft store or wherever else.
Keep the lens light enough so that you can still see the "lines" of where you are going, but dark enough so that when you weld: it doesn't illuminate much more then that. Obviously you dont want to see the whole workpiece from the brightness created by the arc.
When the lens setting is too bright, you can get too much light pass through. After a day of welding (or just a few hours if its REALLY bad) your eyes will develop blisters on the retina. I've had this happen a few times, not knowing the cause.
Basically when this does happen: it feels like you have some sand or "dirt" (etc) in the eye, and its very painful in general, leave alone to look into bright light.
It wont hit you until the evening, by then its too late, as it'll be painful in the evening and MUCH more painful the next day. You'll think you got something in your eye and will want to flush it out with water, but doing so wont do anything. Instead eye drops are the only band aid remedy. It will go away in a day or two after that. But consistant repetition will ruin your eyesight in time.
Instead the best re
 

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Discussion Starter · #9 ·
Yeah welder's flash does suck, when I got steel in my eye it felt the same way. Another thing that helps is if you hold the stinger the right way the arc will illuminate the pool and the area ahead of what you're welding, but you won't actually see the arc. I find this method helps me see too.

Small product endorsement, Home depot sells an auto darkening helmet for like 80 bucks, it doesn't have any settings or anything but it's a good helmet. It may seem a bit bright at first, but you'll get used to it pretty quick, and it's not bright enough to give you a flash. Plus no batteries.
 

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^ Interesting technique. LOL I was about to say I'll try that but i was just layed off on Friday so, thats that. :lol: When things pick up I will though. Thanks. :tup:
 

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Dave-

The "c" bead is what I use most. I'm used to welding thicker metals, so that works great. The other guy I work with does a "Z" bead, and it looks weird, but hell, it's strong!!!

and yes, Home depot auto-darkening helmets FTW!!!

Also Graham... I've tried the Chalk thing, and it does work yes, but not for me.. I pay to much attention to the lines, and next thing i know I have a weird bead going on... But, It does work!


*edit

I know we're talking abut mig welding... But, don't use Auto darkening helmets for Tig welding... Wow, my eyes hurt for days after that!! Learned my lesson the first time, never again!!
 

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^ The settings must be off. All the guys at work that do TIG all day use auto darkening, and never any problems.
 

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that may be it, but I still don't use em when doing Tig... But, I only do tig maybe 1-2 times a year.
 

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Discussion Starter · #14 ·
Was it too bright? Either the shade was too low (if you have variable settings) or maybe your helmet's reaction time is slow. My coworker has a $300 Speedglas helmet and he uses my home depot shield for the very rare TIG job.
 
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