Welding is a method of joining two metals together by bringing them to their melting point and adding a filler metal. Melting together without a filler is called “fusing;” it has its place.

We have four methods of welding in our metal shop:

• • Stick (SMAW – Shielded Metal Arc Welding)
  • Gas (Oxy Acetylene Welding)
  • MIG (GMAW – Gas Metal Arc Welding, Metal Inert Gas, or Wire Feed Welding)
  • TIG (GTAW – Gas Tungsten Arc Welding, Tungsten Inert Gas Welding)

We also have Brazing, and Silicon-Bronze Welding, which uses a lower melting temperature filler metal (usually a Bronze alloy).

Each method of welding (or fusing, or brazing) has its place; there is not one type that will do everything.

FIRSTLY!  ARC WELDING SAFETY!!

STICK WELDING

WORKSHEET to go with POWERPOINT

Stick welding is also known as Arc Welding or SMAW (Shielded Metal Arc Welding).

Stick welding uses electricity to melt metals together. Extra metal is added from the consumable rod to the molten puddle to “build up” the weld (called the “weld bead”).

The extra metal added in stick welding come from “rods,” which have a coating around them. The coating helps control the electricity (the “Arc”), and also melts off, cleaning the metal, and shielding the molten puddle from absorbing oxygen out of the air (making the weld porous and weak), and also insulates the weld as it cools for an annealing effect (less brittle). This coating turns as hard and as brittle as glass, and must be chipped off (wear good eye protection).

The light (called “flash”) from Arc is very damaging – do not have any exposed skin: wear leather and a dark tinted welding mask. DO NOT look at the arc without a welding mask!!!

Stick welding continues to be the most popular in heavy industry and way out in the toolies off the back of a truck.

Want to make huge money? Some stick welding can be done under water!

TIPS & TECHNIQUES

Generally you will chose your current based on the thickness of the rod. A 1/8″ rod will like to work around 75 to125 amps. You want enough current to create a good puddle. Too little will just make the rod stick. Remember CLAMS:

• • CURRENT – choose the right current for the rod
  • LENGTH OF ARC – keep the arc length the same as the rod thickness
  • ANGLE OF TRAVEL – Hold the rod about 5 to 15° off of vertical. You should DRAG the rod in the direction you want to go for most welding positions. PUSH the rod when welding vertically.
  • MANIPULATION – Weaving the rod back and forth creates a wider weld bead, and helps attach other pieces depending on what you are welding. Every welder has their own “style” – try things, observe others, and see what works for you
  • SPEED OF TRAVEL – Try to move at about the same rate the rod is being consumed

Remember – if your weld looks like poo, it won’t hold – grind it out and do it again. This is a skill, and developing skill takes practice.

Stay off the metal about the thickness of the rod

Angle rod about 15° off vertical, pointing in the direction you came from

No “Heat Affected Zone” (HAZ), chunky and gross = Too cold, erratic height and travel = turn up the current and be smoother!

Huge HAZ = turn the heat down

Rod sticking = either too close, or not enough current

Lots of snot balls, huge HAZ, wide bead = Arc length too big = move closer

Wide ripples, low HAZ = moving too fast

High HAZ, tight ripples, wide bead = moving too slow

Low HAZ, small bead = too cold, turn up the current!

Watch the first 3 minutes of Stick Welding Tips from Bubba

GAS WELDING

WORKSHEET to go with VIDEO

Oxy Acetylene (Gas) Welding uses a highly unstable fuel (Acetylene) and pure Oxygen to create a flame that is hot enough to melt the base material together (about 5800°F). A filler material is usually added to the molten puddle to “build up” the weld.

A properly setup torch, can weld pretty much all metals (steel, aluminum, stainless…), as well as heat things up for bending or shaping, and with a cutting torch head, cut metal too!

Fitment is important with this type of welding, since it is very difficult to weld air (good fitment ensures a good weld).

The #1 rookie mistake is not getting a good puddle started – you want a good hot puddle to add filler rod to, NOT “snot ball” drip molten rod onto the cold steel. If your weld bead looks like you blew your nose on it, dude – ewww.

EQUIPMENT

You will need an Oxy-Acetylene welding set, a pair of proper gas-welding tinted goggles and some leather gloves (these tinted goggles are NOT suitable for electric arc welding).

The torch set consists of a handle and tip, regulators, a tank of Oxygen and a tank of Acetylene.

The Oxygen tank is extremely high pressure, and to prevent leaks the tank valve will be either fully open or fully closed. If the valve is not fully open in use, high pressure oxygen will leak past the internal seals into the atmosphere. Pure Oxygen is expensive – so let’s keep the valve in the bottle!

The Acetylene tank is highly unstable. It must be kept upright, and the tank valve is only cracked 1/4 turn (“A twist-o’-the-wrist”) so that you can shut it off in a hurry, instead of going “oh crap, oh crap, oh crap, oh crap…” frantically trying to close a wide open tank valve. The Acetylene is not as high a tank pressure as the oxygen.

Just like your barbeque tank is “fixed” to your barbeque, Oxy-Acetylene tanks must be secured to their stand or to the wall with chain so they cannot fall over.

The high tank pressure is regulated down to a useable pressure – 5psi for most of the welding we do here.

STARTING THE TORCH

• • Let’s assume the tank and torch valves are closed and the lines are empty
  • Slowly turn the Oxygen regulator valve clockwise until the gauge reads about 5psi
  • Slowly turn the Acetylene regulator valve clockwise until the gauge reads about 5psi (NEVER exceed 15psi – it’s unstable)
  • Crack open the Acetylene valve on the torch handle counter-clockwise just a bit, and light the torch with a striker(NEVER use matches or a lighter!!)
  • Adjust the the Acetylene torch valve until the orange flame has no smoke coming off
  • Slowly crack open the Oxygen torch valve until you get a neutral flame (the two blue cones come together)

Carbonizing (or Carburizing) flame = not enough oxygen

Neutral flame = perfect

Oxidizing flame = too much oxygen

TIPS & TECHNIQUES

I find gas welding very therapeutic; it is very relaxing. The single most important thing about any type of welding is that you must be comfortable.

• • Get comfy
  • Keep the small blue cone about a millimeter or two above the metal
  • Angle the torch about 30° off of vertical, with the flame pointing in the direction you want to go
  • Heat the base metal up until you form a puddle
  • Dip the filler rod into the puddle to build it up. If the puddle cools off right away, the filler rod is too large
  • As soon as the filler rod melts, use the torch flame to move the puddle where you want to go, dipping the filler rod into the puddle as you go (move, dip, move, dip, etc., it’s a rhythm)
    • The puddle will follow the heat, so heat where you want to go
    • Don’t let the metal get too hot, or the puddle will grow and run all over the place – I lift the torch away every so often to let the base metal cool down a bit (rhythm)
  • At the end of your bead, add a lot more filler rod before you take the torch away – this prevents “cratering”

SHUTTING OFF THE TORCH

• • Close the Acetylene torch valve (the flowing oxygen will keep the flame out of the torch)
  • Close the Oxygen torch valve
  • Close both tank valves (Oxygen was open fully, Acetylene was open 1/4 turn)
  • Open torch valves to bleed off the gasses in the torch and hoses (Tanks are closed – let’s not bleed off the tanks)
  • Close the torch valves once both gauges read zero
  • Back off the regulators

BRAZING

Brazing is a method of joining two metals using a third, lower-melting-temperature metal as a filler.

Braze is best used for small and delicate components where other methods would end up looking really sloppy and make the project look like garbage. In the bad old days all tube-frame race cars and aircraft frames were brazed. Today, many bicycle frames are brazed (or silicon-bronze-welded: a better weld).

Braze itself has no structural strength – its strength is in the bond, so the fitment of the parts before welding is very important. In brazing “more” is not “merrier.”

Hot metal will absorb oxygen out of the air and make bad welds. Brazing uses a flux (usually coated on the brazing rods) which melts first, cleans the metal surface, and coats the braze to protect it as it cools. DON’T break the flux off the brazing rods, you need it!

The difference in technique between Gas Welding and Brazing:

• Get the metal up to red in colour, NOT liquid.
• Touch the brazing rod to the red, it should “fizzle” and melt
• Move ahead, with the flame pointing in the way you want to go (the braze will follow the heat)
• Dip the filler into the molten braze, and move ahead (dip-move-dip-move-dip-move…)
• You want the braze JUST at the point of melting, NO HIGHER.
  • Overheat the braze, and the fumes can cause “Bronze Fever:” not much pushing, but a LOT of wiping.

One of the advantages of Brazing, it produces a smooth, flowing “weld,” and it can easily be UN-Brazed.

DO NOT grind braze – it pollutes the stone.

MIG WELDING

WORKSHEET to go with POWERPOINT

MIG stands for Metal Inert Gas, also known as “Wire Feed” and GMAW (Gas Metal Arc Welding).

MIG welding involves an electrically charged wire that melts the base metal, and more wire is added automatically to form the weld bead. A shielding gas (usually CO2/Argon mix, or even CO2) prevents the molten metal from absorbing oxygen from the atmosphere.

The light (called “flash”) from MIG is very damaging – do not have any exposed skin: wear leather and a dark tinted welding mask. DO NOT look at the arc without a welding mask!!!

MIG is probably the easiest type of welding to master. I joke that “a drunken one-armed monkey can do it.” If you can drag your finger across a desk, you haz da mad tyte skilz yo.

TIPS & TECHNIQUES

Most MIG welders have a chart inside them that tells you what voltage, what wire speed and what gas flow you need based on what you are welding. The charts are an excellent place to start. I tend to go more by feel.

• • Aim for about 3/8″ to 1/2″ of “stick out” of the wire – you will find the “happy distance” where the welder welds best
  • Lean the torch about 15° off of vertical
  • PUSH the torch in the direction you want to weld on thin metal (nozzle pointing in the direction you want to go)
  • PULL the torch in the direction you want to weld on thick metal (nozzle pointing in the direction you came from)
  • Follow the Heat and Wire Feed settings found inside the welder door – typically:
    • Run as high a voltage as you can without burning through, or undercutting
    • Run as little wire feed speed as you can without the wire burning back into the tip
  • Run the gas flow at about 18-25cfh (moon craters in your weld mean you’re out of gas!)

TIG WELDING

WORKSHEET to go with POWERPOINT

TIG stands for Tungsten Inert Gas, also called GTAW (Gas Tungsten Arc Welding).

TIG welding involves an electrically charged Tungsten Electrode that melts the base metal, and more wire is added manually to form the weld bead. A shielding gas (usually 100% Argon) prevents the molten metal from absorbing oxygen from the atmosphere.

The flash from TIG is very damaging – do not have any exposed skin: wear leather and a dark tinted welding mask. DO NOT look at the arc without a welding mask!!!

TIG is probably the hardest type of welding to master. I do not recommend it for beginners. If you have mastered gas welding, TIG is the next step.

In gas welding, you can control the heat somewhat by taking the torch away. You cannot do that with TIG or you lose the arc. Instead, “heat” is controlled by a foot pedal. This means you are doing three things at once:

One hand controls the torch

One hand controls the filler rod

One foot controls the current (heat)

TIG welds are arguably the best for appearances and structural integrity. Welding stainless and welding aluminum is really nice with TIG. TIG welding is very precise, very quiet, with no spatter, no sparks, and little distortion.

TIPS & TECHNIQUES

• • Metal must be STUPID clean
    • Sand or grind it to shiny metal
    • Wipe clean with ACETONE to remove any trace of grease or oil
    • Clean the filler rods too!
  • Use a dedicated wire brush to clean each type of metal you weld
    • I have 3 brushes: one for aluminum, one for steel, and one for stainless
  • Fit-up is critical
  • DC (Direct Current) is best for steel, stainless steel, and chromoly steel
  • AC (Alternating Current) is for aluminum
  • The amount of current you need depends on the thickness of the material:
    • 1/16″ (0.063) material needs 63 amps to weld
    • 1/8″ (0.125) material needs 125 amps to weld
    • 1/4″ (0.250) material needs 250 amps to weld
  • Keep the Tungsten sharpened to a point
  • Keep the Tungsten stickout no larger than the diameter of the cup opening (a gas lens allows more)
  • Stay about 1-2mm off the metal with the tip – NEVER touch the live tip to the puddle or filler metal (it pollutes the tip, which will pollute your weld – STOP and grind it clean)
  • Lean the Torch about 15° off of vertical
  • Hold the filler rod 90° to the Torch
  • Run the gas flow at about 18cfh (moon craters in your weld mean you’re out of gas!)
  • It’s better to run HOTTER and move FASTER, than to go too slow trying to build up heat

Why you should consider using a Gas Lens for your torch:

TIPS & TRICKS

PLASMA CUTTING