I weld mild steel at home to make things I want and to repair things I need.I do not weld aluminum or stainless steel. I make very little artwork with my welder. I am largely self-taught. I am aware of Tim Anderson's Instructable: Cheap Welding for Punks. He included some information I will not cover. I think I have some information he did not cover.
If terms in the next paragraph are new to you, see the Definitions paragraph that follows it. The italicized words are defined there.
Most of my experience is with electric stick welders. They cost less than other welding systems, but require more practice and skill to learn well. Many of the things one must do to get a good weld with a stick welder are not much different from a similar situation using a wire feed welder (penetration, weaving, preventing sag), and I will discuss both at the same time when possible. I will mention a little about oxy-acetylene (gas) welding. But, for the beginning, occasional welder; a wire feed welder makes learning to weld much easier. MIG is generally preferred and more expensive than flux core wire feed welding. Both have their place. People who want to begin welding are often short on cash, and may well choose to begin with a stick welder before possibly moving up to a wire feed welder after a few years, so some attention will be given to stick welding. I have no experience with TIG welding and will not discuss it.
Stick welders have this name because the coated wire welding electrode resembles a stick you might pick up from your lawn.
Wire feed welders use a continuous wire electrode on a spool. Rollers in the welder driven by a motor feed the wire at a steady rate through an electrode holder usually called a gun. Wire feed welders were invented to increase production rates by removing the need to stop and replace a burned electrode.
Penetration means the welder did not merely lay a bead of welding material over the top of a joint, but some of the parent metal melted and fused together below the weld, too.
Weaving is moving the arc from one side of the joint to the other in order to make certain the weld penetrates into both sides of the joint. A weaving pattern is also used to prevent sag when welding in an upward direction on a vertical joint.
Sag is molten metal that flows out of the joint while welding due to the effects of gravity. This can be a problem when the weld is vertical, overhead, or horizontally along the side of a vertical surface. Avoiding excess heat, electrodes designed to harden quickly, the angle at which the arc is directed, and general manipulation of the arc are used to control the weld and counteract sag.
Oxy-acetylene welders use two tanks, one filled with oxygen and the other with acetylene. Both gases flow through hoses at controlled pressures to mix and burn with a very hot pointed flame in a torch.
MIG refers to a wire feed welder that protects the fresh weld from mixing with oxygen in the air by continuously covering the weld area with an inert gas. If oxygen comes into contact with the hot, fresh weld; the weld becomes porous and is weakened.
Flux core welders use a thin wire electrode that has a chemical powder in its center. This powder melts and flows over the weld to protect the fresh weld from oxygen. This hardened coating is called slag. After the weld cools, chip or brush it off, depending on how thick it is.
TIG welders use a torch with a sharp tungsten tip to make a pool of molten metal with an arc. The operator dabs metal from a thin wire rod into the pool. At the same time the operator increases or decreases current to the arc with a foot pedal control. TIG welding makes beautiful welds on aluminum and various special metals. It requires much skill and practice to learn.
Other terms you may see in welding literature (Do not worry about these, unless you encounter them):
SMAW - shielded metal arc welding - stick welding
FCAW - flux cored arc welding
GMAW - gas metal arc welding - MIG welding
GTAW - tungsten inert gas welding - TIG welding
(The photo is from Bing Images.)
Step 1: Educational resources
If you buy a used welder, but no manual comes with it, you can probably download a manual for it or a manual for a machine that is sufficiently similar. There are many helps available for the person who wants to learn to weld. Some are in text (either electronic or on paper) while others are videos.
Miller has some excellent videos for learning to weld or for improving your skills. My favorite is a video on flux core wire welding that was linked in their DIY electronic newsletter for October 2010. Many of the techniques in it are similar to techniques used in stick welding. Text and photos from the video are also at the link. Just scroll down to see the text and photos. Miller's DIY newsletter and some other newsletters from Miller are available free to anyone who wishes to sign up for them. (Archival copies of the electronic newsletters are also available for viewing on-line.) Go to the Miller page linked at the beginning of this paragraph and check the links under Resources for other videos and articles. Manuals for Miller welders and basic welding guides are also available.
Lincoln has various educational materials for learning to do stick or MIG welding, some of which you can download for free. Their book: New Lessons in Arc Welding is very good and is newly updated. For other LIncoln books, go to this link. (Pull down Education Center and go to James F. Lincoln Foundation for Educational Materials.) Also, pull down Support and go to Resources for useful free literature.
Hobart also has several resources under the E-Learning tab and a forum for welders at the Weld Talk forum. (Miller also has a forum on its Resources page.) At the E-Learning tab scroll down to see examples of good and bad welds for MIG and for stick. The second photo also shows a drawn chart of a good stick welding bead compared to various problem weld beads. These photos can help you diagnose what you are doing wrongly and correct it. Photos like these are often available elsewhere, too. Some basic guides to welding can be downloaded, too.
Another good book for the beginning stick weldor is the Forney Welding Manual. It is also out of print. Some used copies are available. Among books currently available, this book is similar in scope and approach to the Lincoln book, except that it gives a dominant treatment to MIG welders.
There are numerous video tutorials on all aspects of welding at YouTube. Some are done well, others are rather poor.
*Technically, a welder is the equipment used to make welds. A weldor is the individual who uses a welder to make welds. Often "welder" is used for both.
(The second image is from Bing Images.)
Step 2: How I started
I made and repaired quite a few things while I had access to his gas welder, including a picnic table from pipe and 2 inch lumber. My welds never broke, but they were always a bit "undercut." I never quite learned to build up a ridge on my weld beads. Jacqueline Kennedy said she painted in a manner her own family could appreciate. That also described my gas welding.
I did learn a lot about moving and controlling a puddle of molten metal, and that skill transfers very well to welding with an electric arc welder, especially a stick welder. There are many things to keep in mind simultaneously while welding even the most simple things, but in the end, it all comes down (in my opinion) to making the molten metal do what you want it to do. All of the things you try to remember really serve that one purpose. It reminds me of a friend who flew jets in the US Air Force. He said after a while the jet simply became an extension of the pilot. The pilot thought it, and the jet responded without the pilot thinking through all of the details. With practice you will be able to observe the behavior of the molten metal and respond to make it do what you want it to do without thinking through all sorts of details.
If you want to see more about how to weld with an oxy-acetylene unit, there are a number of videos at YouTube. Just search for oxy-acetylene welding.
(The photo is from Bing Images.)
Step 3: A stick welder
Welding electrodes (welding rods) have different numbers to describe them. I like 6013 electrodes. Others prefer 7018. 6011 electrodes are also widely used. Each has different characteristics which make it more suitable for certain applications and less suitable for other applications. The numbers provide details on the characteristics of each type of electrode, but those details are beyond the scope of this Instructable.
I committed a common error: I bought more than one welder. First, I bought an inexpensive 120 volt AC stick welder because it cost what I had available in funds at the time.* Later, I realized I really wanted more power to weld heavier steel. Within a couple of years I was buying a used 230 volt stick welder. Since that, I have also bought a flux core wire feed welder. The best plan is to determine what you will need, save for it, and buy only one welder. But, had I done that, I would have waited more years to buy my first welder and would have missed some benefits from having that first welder. Fortunately, there is usually someone who is looking for a good deal on a used welder you no longer use and will buy it.
*Before Dejanews disappeared from the Internet I read a post by a young woman in Arizona. She and some friends needed to repair an iron gate in a cave. They carried a 120 volt stick welder and a Honda generator into the cave and she made the repair. I decided I would buy a 120 volt stick welder if they were that useful.
(The photo is from Bing Images.)
Step 4: Ventilation, UV, and spatter burns
Cover your exposed skin. Arc welding generates UV rays linked to skin cancers. Resist the temptation to peak out from under the welding helmet in order to see while striking the arc. Instead, use a piece of carbon rod. See this Instructable.
Cover up to protect from burns caused by globules of molten metal.
(The photo is of a sunburn and is from Bing Images. It is very much like the burn that comes from welding flash.)
Step 5: Preparation before welding
A friend brought me a bicycle rack for the bumper and trunk lid of their automobile. A 1/2 inch rod had broken off near the end of the threaded portion. She and her husband thought I would simply run a weld bead around the break. They were surprised when I made a deep "V" across the top and bottom of the joint. Then I made a root weld at the thin leading edge of each piece to join them together. See the red oval in the graphic. The root weld is often done with a thinner welding rod or more current or both to guarantee excellent penetration. I waited until the joint had cooled and chipped away the slag. Grind a little on the back side, too, to avoid any slag being trapped under a weld. Such slag inclusions would weaken the weld. I made a weld on both the top and the bottom of the root weld to keep stresses in the metal equalized. See the yellow and blue in the graphic. Clean away the slag after the welds cool and weld on both sides again. I repeated this process until the "V"s were full. Instead of a few minutes, this project took more than an hour to complete. You can see a real life example of this at this Instructable. The same Instructable is also linked in step 7 in regard to preheating.
An old adage is to weld a little and cool a lot. After welding, pounding on the welded joint with a chipping hammer reduces stresses in the weld.
There is also the matter of duty cycle. Every welder has a duty cycle. That means it will overheat and stop welding if used continuously. The duty cycle is often 20/80. That means after welding for 2 minutes (20 percent) you must let the welder cool for 8 minutes (80 percent). Often a weld can be completed in less than 2 minutes and you will need more than 8 minutes to get ready for the next weld, anyway, so it all works out.
Step 6: A good ground
If the finish on the parent metal is not something very special, it is possible to grind away a bare area and attach the ground clamp there. A simple way to get a good ground through heavily painted or plastic coated surfaces without grinding and unnecessarily marring them is to attach a Vise-Grip locking plier very tightly and then connect the ground clamp to the pliers rather than to the work piece.
Step 7: Preheating
Step 8: How to stand
Notice how the weldor in the photo rests his elbow on the work surface and braces his right hand with his left to make himself more steady. Notice also that the weldor is fully covered with a leather jacket and leather gloves.
(The photo is from Google Images.)
Step 9: Striking the arc with a stick welder
Striking an arc with a stick welder has been described as like striking a match. The danger is that the end of the rod sticks on the metal without making an arc. Then the machine begins to growl very unpleasantly. That happens to everyone quite a few times. Quickly jerk your wrist side to side to break the rod loose from the steel. When that happens it usually means I need to increase the amperage a bit on the welder's output. But, higher amperage can also produce too much spatter. The trick is to find the right heat (amperage) for the metal being welded and the rod being used.
In theory, you very lightly scratch the end of the rod on the steel as if it were a match. Think of the pressure you use with your fingernail to scrape a piece of lint from your sleeve. That is about the right amount of pressure when striking an arc. Then you immediately pull the rod away from the metal just a little. Adjust the length of the arc so that you hear the sizzle of bacon frying. Because the rod burns away as you weld, you will need continuously and gradually to lower the electrode holder (stinger) nearer and nearer to the metal to maintain the proper length of the arc. If you find yourself frustrated because the rod frequently sticks when you are trying to strike an arc, see this Instructable for using a carbon rod to help get the arc started. This technique is especially helpful when you have stuck a rod once or twice and the coating is beginning to come off of the end of the rod.
(The drawing is from Google Images.)
Step 10: Some general guidelines on heat settings
3/16 inch rod = 0.187 inch = 190 amps.
5/32 inch rod = 0.155 inch = 150 amps.
1/8 inch rod = 0.125 inch = 125 amps.
3/32 inch rod = 0.094 inch = 90 amps.
5/64 inch rod = 0.078 inch = 75 amps.
1/16 inch rod = 0.062 inch = 60 amps.
My experience indicates that your actual settings would be a little lower than these suggestions. But, it is still a neat correspondence that the rod diameter in thousandths of an inch is very near to the correct amperage setting.
(The photo is from Bing Images.)
Step 11: Do not move too fast
What follows applies to stick, flux core, and MIG welding.
A very common error is to travel or move the arc along the length of the joint too rapidly. This results in a poor and incomplete weld. When you are moving forward along the joint at the right speed, a crescent of light, like an eighth moon will appear at the front edge of the bead near its top. See the yellow crescent in the graphic. Go too fast and you will not see the eighth moon crescent of light. With a little practice you can distinguish this crescent of light from the brilliant flash generated by the arc. Welding is not just laying down a bead of welding rod material over the joint, but it is also melting the parent metal below the surface so it fuses together, too. That is called penetration.
In order to achieve better penetration in your welds, do not butt the two pieces tightly against each other. Instead, leave a small gap between them. That allows the arc to get down between the two pieces and make for a better weld. How much gap depends on the thickness of the metal, the thickness of the rod, and the amperage setting used on the welder's output. This gap should not be too large. Good fit up is also needed. That means there are no large gaps a weld bead cannot bridge in one pass.
The best choice is never to weld "out of position." That means you always hope to weld with the joint below you on a work surface facing upward. 'Out of position" welding happens when the joint is above you, or vertical, or along the side of something like a wall. Special techniques are required for each of these to prevent "sag," which is molten metal flowing away from the joint before it can cool enough to harden. See again the link to the Miller video on flux core welding from step 1.
While you are learning, you can put practice welds into a vise and pound on them with a very large hammer to bend them sharply. You want a weld that does not break, or if it does, it breaks next to the joint in the parent metal, but not in the joint.
Step 12: The hot side is the short side
See the graphic. It is an exaggerated representation of distortion that happens when attempting to weld two pieces to make a 90 degree corner. Notice the red-gold-yellow line at the joint. The weld began with the red and moved along into the gold to finish in the yellow area. (Red represents partial cooling of the weld. Yellow represents the most recent and hottest part of the weld.) The blue arrows represent the direction in which the pieces are being distorted away from the dotted lines, which represent the square corner the weldor intended.
There are several things you can do as preventive or corrective measures.
You can plan the order and the direction in which you weld the pieces together to minimize the shrinkage effect. You can tack weld the sides of a joint and check the setup before going farther. Hopefully, the tack welds will restrict the shrinkage.
You can guess how much shrinkage there will be and open the placement of the setup, assuming you are welding from the outer part of the corner toward the inner part, so that the pieces will be positioned properly when the welds cool; but this is almost like forecasting winning numbers for the lottery. Still, make a guess on opening the joint. Take measurements. Open the joint an extra 1/16 inch over 12 inches for 1/8 inch thick angle iron 1 inch in size. Weld and measure the finished product when it has cooled. Cut the joint open and adjust the amount the joint is opened for compensation. Weld again and check.
You can clamp the pieces to something solid before welding and pound on them while cooling to relieve stresses in the hope that the pieces do not move during their cooling.
You can check the pieces after they have cooled, heat them, and bend them back to their desired position.
In general, avoid excess welding heat and avoid more passes than necessary.
Hot steel will always contract when it cools, and welding involves hot steel. Do some planning and build in a way to leave an open door for making corrections.
One other note of caution: Welding across a load bearing member creates a weakened area prone to breakage. Welds to a load bearing member should always be parallel to the length of the member.
Step 13: Cast iron
Once I welded a garden rake made of cast iron. The weld had a very nice appearance, but as soon as the tines of the rake dropped onto the ground, the joint broke open at the weld. I pounded the thin piece of cast iron on both sides of the joint until it was only lukewarm. That weld held just fine and never broke under use.
I have not done larger things in cast iron, like the side of an engine block that cracked after freezing with no anti-freeze protection. I have heard about others doing that. They welded a little in one spot and then moved on several inches to another. After just a little they moved on a few inches to yet another. Eventually they welded a little more on the first bead and then the next and the next. They kept this rotation going until they had finished. The idea was to avoid heating any one spot excessively.
(The photo is from Bing Images.)
Step 14: Helpful accessories
I insert partially used electrodes so the burned end is near the mouth of the keeper. That way I can find them easily and use them before I start a new rod.
A carbon arc torch is a very useful accessory for a 230 volt stick welder. It allows heating steel for easy bending. See this Instructable.
I have a piece of 1 1/2 inch aluminum angle about 18 inches long. Steel does not stick to aluminum, so there is no danger I will weld something to the aluminum. It makes a handy accessory to put into my vise. I can clamp things to it before welding. See this Instructable for how I have used it for that. It is a help when welding thin materials that might burn through easily. The aluminum acts as a backing plate to absorb extra heat and to prevent blowing holes in the thin steel. Still, I must weld in short bursts with my wire feed welder, or I could still burn a hole. I can even turn it over so it is like "V" and then I can lay two pieces of rod into the "V" for welding them end-to-end while keeping them aligned. You can see an example of how I use a piece of angle for aligning and holding rods for end-to-end welding in step 12 of this Instructable.
The day will come when a friend brings something to be welded by you, and the friend needs eye protection. An inexpensive extra welding mask is good to have.
Step 15: Wire feed welders
MIG capable welders are more costly than flux core welders because they include a gauge for regulating the shielding gas flow, a tube around the gun liner for carrying the gas to the gun, and a solenoid valve to start and stop the gas flow when the arc begins and stops. There is also the cost of the gas and a steel bottle to contain it. MIG welders can be used with flux core wire, but flux core welders cannot be outfitted as MIG welders. The advantage of MIG welders is that the welds have a better appearance and better penetration. There is also less cleanup after welding. But, in windy conditions the gas that shields MIG welds can be blown away before it does its job. MIG welding requires very clean steel while flux core welders can dig through some surface impurities to make a good weld. Flux core welders can be used in windy conditions with no problems.
In stick welding attention is given to the length of the arc. With wire feed welding the amount of wire sticking out of the end of the copper welding tip at the end of the welding gun becomes important. See the manual for your welder.
Wire feed welders are much easier to use than stick welders. They do not require the same skill level and amount of practice as stick welding. Some say laying a bead with a wire feed welder is like putting down a bead of toothpaste on a countertop. Almost anyone can do that. But, it is much more difficult to see where you are welding with a wire feed welder. It is not uncommon to wander off of the joint while welding with a wire feed welder. See the next step for three solutions.
Turn on your wire feed welder and let it run for a minute or so before beginning to weld.
In order to be sure your weld has good penetration and is not a "cold weld" (weld material laid over the parent metal without any real bonding), look for blue discolorations in the parent metal on both the left and right sides of the weld as a sign of good penetration.
When it is time to stop welding with a stick welder, the weldor simply pulls the electrode away from the steel and the arc stops. Those who are used to stick welders need to learn to release the trigger on the gun before pulling the gun up and away from the steel. Failure to do this results in a couple of inches of wasted electrode wire sticking out of the gun. This must be trimmed before beginning to weld again.
With my flux core welder I can sometimes begin a new weld without trimming the burned end, but there are other times when an arc will not begin without first trimming the wire to make a fresh new end.
There are some good videos on YouTube for how to do MIG welding.
(The photo is from Bing Images.)
Step 16: Staying on the joint line
I made a small discovery that helps me keep the arc on the joint. Debate rages whether to push or to pull the gun when welding with a wire feed welder. I generally pull it. I noticed I can look under the gun ahead of where it is welding and there is enough light from the arc that I can see a little of the unwelded joint to use as a guide for moving the gun. That works unless the sun is coming from over my shoulder. In that case the inside of the helmet is bright and I have great difficulty seeing even the arc. See the smaller of the two text boxes in the photo.
Welding helmets come with clear lenses over the tinted lenses. These become dirty and pitted, even discolored. All of those things affect visibility. Periodically clean or replace the clear lenses. I use a Lincoln auto-darkening hood I bought in 2004. Although most auto-darkening hoods use solar cells and contain lithium-ion batteries, mine uses two AAA batteries. My helmet has never failed to darken as it should, but a family member told me I need to replace my helmet because (he believes) auto helmets darken their lenses excessively after a few years. As a last effort before replacing my trusty helmet, I replaced the AAA batteries, even though the old batteries still appear to work just fine. To my surprise, new batteries cause my helmet to darken my non-adjustable lens less and I can see the weld joint fairly well when using my wire feed welder. In the future I will check my clear lenses and replace the batteries regularly. Lithium-ion batteries no longer take a full charge after about four years of use. Those whose helmets use solar cells and rechargeable batteries should look into replacing the batteries and see if that helps visibility while welding.
And, some clamp down a guide for their hand to follow. This might be a piece of board about 1 inch thick. The heel of one hand can ride against it to give a straight line guide for following the seam to be welded. See the larger of the two text boxes in the photo.
Step 17: When to replace the wire feed's tip
The photo shows a 0.030 inch tip I have retired. I polished the end so the hole is more visible. Notice that it is no longer perfectly round. The welder worked better with a new tip and seemed to have a better arc.
Step 18: For the ladies
Step 19: Make your own stick welder?
A used welder can be a good buy. Watch estate sales and other auctions, as well as Craigslist for your area. I bought my 230 volt Miller Thunderbolt stick welder on eBay. The photo was muddy-looking and no one else bid on it. The very good auction price became a quite reasonable price after shipping costs were added. It has been a great welder. I bought my Hobart flux core wire feed welder as a factory refurbished unit. No one has much good to say about cheap import welders. Owners are usually soon disappointed.
(The photo is from Google Images.)