It means the voltage is not in relation to ground but to the other side of the loop of the transformer; the ground clamp remember : the torch has a difference in potential with that clamp and anything conductive it touches. For current to flow in that circuit there has to be an electric connection between the torch and the clamp.
A normal circuit (without the isolated transformer) features a voltage vs. ground : that is because the generator hasn’t got two wires coming from it: the role of the other wire is taken by the ground. In this case the live wire does have a difference in potential to the ground. (That’s why there are no return lines on a transmission pylon).
The isolated transformer takes that difference in potential between the live wire and the ground (in this context there is no meaningful difference between a 0V wire and a ground wire) to create a magnetic field in a piece of metal, with that magnetic field it creates a difference in potential between the torch and the clamp. This circuit has no potential vs. normal ground.
To the OP, welding is great fun and if you looking critically at your work not very hard to learn. Just a few tips:
the pretty blue light has a lot of UV in it and will damage your eyes; I don’t know the English term for it but “welders flash”? Feels like you rubbed a hand full of sand in your eyes. Your uncovered skin also tans and burns quickly: cover up.
Wear clothes with tight cuffs and collars, tiny splashes of hot metal will fly around.
When you are welding: keep your welding gloves on. Metal can be very hot long after it stopped glowing white or red. Grinding also heats up any metal you’re working on.
Work in a well ventilated room; the fumes can be nasty.
Try to find samples of the metal you’ll be working on to see if your welder is set up right.
A workshop often has flammable materials, take a minute to look at your immediate surroundings before you start working with an electric arc (which is a very hot open flame)
Electronics do not take kindly to metal dust (which you’ll be making lots of, every starting welder has to wield the grinder a lot).
Wear real goggles, the kind that seal to your face around your eyes when grinding metal. Little bits of metal can go flying into your eyes, you may not feel it, or ever know it, until you get an MRI, and then the magnet can rip those little shreds right out of your eye doing much more damage than when they went in.
If you’re working with thin stuff, a good MIG is hard to beat. To me it’s also the easiest to learn to weld with. I can MIG pretty easy, stick is still rough for me. TIG…well, has been a learning experience.
As others said, protection for yourself is #1. Get a good helmet, and ALWAYS wear it. Auto-darkening is the way to go. My family has professional Jackson and other brand helmets, great stuff. I bought one from Menards. Compare the size of the windows, go as big as you can. I’d get one with replaceable batteries (the Harbor Freight specials don’t seem to have that)
Wear LEATHER gloves. If you MIG you might find the thick stereotypical welding gloves TOO thick and hard to maneuver. Wear good long sleeved shirts, cotton or other natural material, an actual welding jacket is a good idea. Same thing with pants. And shoes. Definitely leather boots. Cover up all your skin to avoid a free tanning salon. I’ve gotten sunburn from it, very not fun.
You can touch the work and weld at the same time, no danger of shock. The only time it can be a danger is if you’re welding on something wet and happen to be between the work and the ground. I’ve never tried it, but apparently it’s an exhilarating experience.
Be very aware that when welding, sparks go EVERYWHERE. Remove ALL flammable material from the area. Have a fire extinguisher handy and a jug of water for small stuff. Heavy globs of hot melting steel tend to go down. Onto your legs or shoes. I’ve caught myself clothes fire before…
HOT steel looks the same as COLD steel. Grab carefully.
In welding, preparation is key. Remember it’s all electrical. You need good connections. The ground needs to be connected to a shiny clean piece of steel. The piece or pieces of steel that you plan to weld also need to be clean in the area of the weld.
On that note, if you plan to weld, you need a grinder. 4 1/2 inch angle grinders are the usual tool of choice. They have guards. USE THEM. Skin and fingers are removed much faster then steel.
Practice is the only way to get good. Don’t be afraid to screw up. You can usually grind the mistake off and try again.
It’s not scary or hard, just long winded to explain. Try it and have fun!
I had that happen about three years ago. I was wearing glasses, but they were two bit, not really safety glasses, so didn’t cover that much area. I had been using the harbor freight, 4 ½” grinding wheel that is so popular these days. It sent little pieces of metal into my eye that managed to somehow find their way past the little glasses I had on. Dealt with it for about a week, fooled around and let it get infected. Most painful thing to date I had to experience, was the eye doctor pulling that stuff out of my eye, and me having to keep my eye open. He was rough too, and got a little frustrated with me, took him multiple times to get the three little pieces of metal fragment out. Man he was rough! Oh, I said that already. After that, gave me some antibiotics, and I was good as ever. I’ve always been safety conscious, but there are times I’m slightly a bit more lax than others. That was one of ‘em.
Speaking of another, I’ve caught myself on fire too. That happened about ten years ago while up on almost the top rung of a 16’ ladder welding outside. I grabbed a long sleeve shirt to protect myself against flash burn. It was an old welding shirt, but I also used that dirty shirt to fill up gas and change oil, and evidently a whole lot of flammable chemicals must have worked into the shirt over time.
Anyway, there I was, on the top run, doing some overhead welding. It was a hot summer day in TX, hotter than most. It was fixin’ to get a lot hotter, quick! As the hood was down, sparks flying everywhere, I kept thinking, damn, this day it really turning out to be a scorcher. Every welder sort of gets used to little sparks burning through on occasion, you sort of get used to it, and I was determined to keep welding, and just toughen up. But it’s getting hotter, and hotter, shirt is on fire, and before I knew it, the flames started reaching up under my welding hood. I immediate stop welding, throw my hood off, drop my stinger, I’m going as fast I could to get down to the bottom rung, all the while slapping myself with both hands with the gloves on trying to get the fire out. I had it mostly out by the time I got to the bottom. Chest was fairly red, but also had a t-shirt underneath which I guess prevented it from giving me serious burns.
That was one of my favorite welding shirts too. My cousin gave me a nice navy blue working shirt, that had a name patch which said Drut on it. I just liked that stupid name for whatever reason. Never gave it much thought, then one day, my gf asked me, “you realize what it spells backwards, don’t you?” It actually made me love that shirt even more. It was good for laughs. I was able to save the name patch. Just haven’t got it sewed on to another work shirt yet, but intend to.
I have scared the shit out of myself more than once welding. I was welding some 2" steel tubing that had cracks in the joints. I used brake clean to clean off the oil. The cleaner seeped into the pipes and exploded when the welder arced. No damage but shook me up.
I have taught myself to weld. It helps a lot if you can have a “real” weldor, or weld inspector critique your work. Undercut, lack of penetration, and many other faults can be hard to see until someone shows you what to look for.
Once you know what a good weld looks like, you can experiment until you can make them look like that. Get 2-3 good books. Try what they say. When it doesn’t work, go back and read again, and you should then see what they are really saying. Wash, rinse, repeat.
If you possibly can, I’d say try to learn Oxy-Acetylene first. It is a slow process, but that gives you time to learn. You learn to manage the heat, the puddle size, filler, etc. TIG is very similar to O-A, just a cleaner, hotter torch basically.
MIG is dead easy, but also dead easy to make crap welds that look OK to the uninitiated. It is really fast, so you actually need some skill to make a good weld happen in the limited time.
Stick is the cheapest, so it is where a lot of people start, but IMO takes the most skill of any process. You have to strike and manage the arc, but it also keeps adding filler like MIG. It is easy for a beginner to end up with huge arc craters, and slag inclusions. Stick welding thin material is difficult at best, and impossible for a beginner. Most heavy industrial welding, like pipelines, is stick, so a skilled weldor can make great welds, but there is a reason they are well paid.
An automatic darkening welding helmet will be a great help to a beginner, especially stick welding. It takes a while to learn to strike an arc, and it takes longer when you have to do it blind.
You can learn a lot with just a few hours of instruction, but to get good you need to practice.
Brake clean is bad news around welding at least the chlorinated style. It releases phosgene gas when heated. Thats one of the reasons there is non-chlorinated Barake Clean now (green can). For light cleaning and cleaning right before welding, I use acetone. It evaporates quickly so less chance of fire.
Like the others said MIG is easy enough to learn but it is also easy to get a good looking weld with poor peneteration especially with one of the smaller welders. So stick to non-critical projects while you are learning. The type of repairs you are talking about should be no problem. There are lots of scary stories of amatuers building themselves trailers/deer stands with limited skills and a small welder and then having their welds break at bad times.
So, tons of good info here (and thank you all), but I’m still conflicted on MIG (that’s wire fed, right) and stick.
The only reason I chose wire fed is because I heard it’s easier to get a spark started and the website I clicked on first said it’s much easier to learn on.
So, just pretending, for the moment, because this isn’t happening today, I went with a wire fed welder, it looks like the difference between non-gas and gas is a few hundred dollars. I assume I can get a non-gas model and get wire with flux and be fine.
Second, am I safe getting a 110 volt model or is it better to start with 220?
Not that it makes a difference, but I’m not planning to run a 20a (or whatever I need) outlet all the way to my garage. My plan would be to put one near my breaker box and make an extension cord, with the correct gauge wire, long enough to get to where I need it. It’s really no different than ‘properly’ wiring it, but the Romex just wouldn’t be buried in the wall. This would also give me the ability to create the same setup at work (in a remote location with a sub panel, away from everyone), with minimal expense. I also see there’s welding extension cords online.
Lastly, not that it’s really here nor there, but I do already have a 4.5inch angle grinder. It’s one of my favorite tools, it’s a nice Hitachi that I picked up as an open box item at Home Depot for something like $40. I’ve probably spent twice that on wheels since then. It’s actually one of the ‘you should buy this tool when you get a house’ things I recommend, often even before a Sawzall. I love my Sawzall, but this thing is just that good.
But, like you guys said, eyes and ears before using the grinder. It’s louder than you’d expect and throws crap everywhere. Also, I always tell people to make sure they have a good grip on it when they turn it on. It’s got a whole lot more torque, and not in the direction, that you’d expect and I’d hate to see it get dropped if they lock it on. Don’t really want to see that thing scatter across the floor.
It is possible to get electrocuted welding. I’ve handled at least two instances of guys killed this way, both working in trawler engine rooms in the tropics. It’s the combination of lots of steel, damp, salt, sweat and guys sitting or lying in their sweaty overalls to get access to what they are welding.
I have an extension cord like you mention, it’s sufficient for my needs. I used to have a real 220V 40A extension cord, lent it to someone, never saw that again. Now I have 75 foot leads for my stick welder, there’s some current loss there, but it beats dragging that thing up and down the basement steps.
I don’t think much of the 110V welders I’ve seen, either stick or MIG, but I’ve only seen the extra cheap units. As mentioned MIG seems easy, but the welds may not be as good as you think. If you’re doing small things you may not notice the next part, many electric welders have a duty cycle. A 20% duty cycle may mean you can only weld for 2 minutes out of 10 minutes. For small welds that will be plenty, if you want to build a trailer you’ll spend a lot of time welding. Small MIGs and small AC stick welders will have restrictions like that. Get an old Lincoln Tombstone arc welder and you’ll be able to weld non-stop. Also I wouldn’t trust a cheap used MIG welder, the wire feed mechanism may be a mess and if the gas feed leaks too you could end up replacing most of the welder to get it working right.
Some were feed welders will only handle flux cored wire while others handle both flux cored and plain, with gas of course. While one that only uses flux cored will be cheaper I believe that there is no flux cored wire for aluminum. But I’m not certain about that.
Using gas eliminates most all of the stage, but I’m told that if you’re outdoors in a breeze flux cored is better. Anyone have different information please educate me.
I have a 115V hobart 130 mig that runs OK on a 100’ AWG10 cord.
As for aluminum…you need to run pure Argon gas. Also soft aluminum wire doesn’t push down a cable very well…you will spend much time untangling the feeder. It is usual to use a spool gun with Aluminum…1 lb spool on the gun, so it doesn’t have to be pushed down a long bendy cable.
TIG is a much better process for aluminum. Or O-A with flux for thinner stuff.
One more time: It is easy to make crappy welds with a MIG. It takes some learning to make good welds with any process.
Actually for most aluminum work you would attempt yourself aluminum brazing rods will do the job. These are made of an alloy with a low melting point, you can use a propane torch, although MAP works better. It’s a little tricky to learn to use, it’s not like soldering. I’ve only played with this a little, but once you understand the process it seems to work very well for any non-ferrous metals.
One trick to doing the aluminum brazing I picked up. Use the acetylene with no oxy to smoke the two pieces being welded, once they are covered in black smoke start preheating with a torch until the smoke suddenly dissapears on both pieces. Now it is ready to start brazing.
I assume that’s the point where the carbon oxidizes and comes off as a gas. Never tried that, but it seems like a reasonable indication of temperature. What I found out was that you need to tin the areas to be brazed with the rod first. While the material is still liquid you scratch the aluminum underneath to loosen the aluminum oxide which then floats up and you push it off. When the pure aluminum underneath contacts the molten rod material it alloys into it. Once you have a layer of rod material on top of the aluminum you can join two pieces like that or build up more material on top. The alloy material doesn’t form an oxide layer the way aluminum does so you don’t have to do anything special to continue brazing.
I’m impressed with how good this stuff works. I remember aluminum brazing rods way back when that were totally worthless, just laid blobs of material on top of aluminum.