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Avoiding Weld Schmerz

February 3rd, 2017

More Stuff I Don’t Actually Need to Do

Having had great success with my welded box wrench bottle opener, I am planning to do some more metalworking projects. It occurred to me that turning trash into useful objects would be an effective and inexpensive way to improve my abysmal welding skills. I’m thinking I may hit the flea markets this weekend and pick up some junk to work on.

I really need practice. I had some problems with the last two items I welded.

In 2016, I used stainless wire to weld the corner back onto a cast iron motor base. The weld worked, but it was very ugly, and there was a lot of spatter. I couldn’t see a thing when I welded it, so the weld wandered around a bit, and I also deposited too much wire. Experiences like this are the reason I’m so good at using the angle grinder.

When I welded the wrench/opener, I still couldn’t see, and I ended up with blobs that had to be ground off. The spatter was also bad.

Day before yesterday, I took out some scrap steel and ran some beads on it, and I discovered the cause of the poor visibility. The welder’s shade was set too dark. I guess that should have been obvious, but when I was welding the motor and opener, I had this dim memory of having tried adjusting the darkness setting, and I thought it wouldn’t work. Clearly I was wrong. D’OH.

As for the spatter, I learned that 75/25 is the wrong gas for stainless. People are telling me to use pure argon. Something about the CO2 reacting with stainless. They say it causes spatter and also makes joints rust. There is also something called “tri-mix,” which contains helium as well as argon and CO2. I am told it works really well, and that if you know what you’re doing, you can do just about any type of electric welding with only three tanks. Supposedly you can connect the tanks and create mixtures. Don’t ask me if that’s true.

I decided to get an argon tank. I learned a few things about buying gas and tanks, so I am here to pass it on. Don’t assume I’m right, especially if you live outside the US.

First of all, there are two types of tanks. Some tanks are company-owned rentals, and others are customer-owned.

Company tanks have the names of the companies stamped somewhere on the neck. If you buy one of these tanks from a private party, you may be receiving stolen goods, and if you take it to be refilled, two things can happen. You may be turned away, and the tank may be confiscated. This is bad.

Customer tanks have “slick” necks (people use that word to describe them). No stamps, except for regulatory stuff like test dates. If you have a tank like this, you can take it anywhere to be filled, and you won’t have a problem.

If you have a customer tank, and you want to swap it instead of getting it filled, you need to tell the gas people when you bring it in. If you don’t, they may do two things. First, they may give you a rental tank, and then you have to keep bringing it back to them forever, and they think they own it. Second, they may stamp their name on your tank, which is another way of saying they may steal it.

These things are also bad.

When I got my MIG, I bought a new tank. I thought this was a smart thing to do. I think it was around $140, empty. Imagine my surprise when Airgas swapped me an old one for it instead of filling it. I wanted to use my pretty new tank, but they gave me a crappy one that wasn’t shiny at all. Oh well.

Intelligent people do not buy new tanks. Well…they don’t do it twice. Although I do have two CO2 tanks I bought new, and I bought a beer gas tank new. Okay, they don’t do it five times. That’s my story.

You can buy used tanks and save a lot of loot. If you buy used, you need to make sure a) the tanks are customer tanks, and b) their test stamps are valid, or at least they are still in good enough shape to be tested. If you buy a tank that’s expired but still okay, you will have to pay a certification fee when you turn it in for a swap, but at least they won’t discard it. If the stamp is good when you refill it, you will have no problems at all.

Luckily for me, the Airgas I used did not give me a rental tank, so I still own whatever is currently attached to my welder, and I can get it filled anywhere. Also, they confirm that I can buy a used tank somewhere else and get it swapped at their shop. You need to look into things like this before you buy used tanks.

Final thing: small tanks are generally not rentals, so the stuff I wrote above may not apply to you.

I found a guy on Craigslist, and he sells full tanks cheap. He swears they’re up to date, and that they’re all customer tanks. I decided to give him a try. Today he’s bringing me 125 cubic feet of argon for $120. We will see if it’s a good deal or not. Hopefully it won’t turn out to be propane or mustard gas.

My existing tank is 80 cubic feet. Because I started with a new tank, I went a little cheap. A bigger tank would have cost a lot more. I now think I made a mistake. A bigger tank will last a lot longer, it won’t be much heavier, and it will fit on the same cart. It probably makes more sense to have a 125 cu. ft. 75/25 tank and an 80 cu. ft. argon tank, since one doesn’t generally weld stainless, but I have what I have.

I sincerely hope the Craigslist guy isn’t a complete crook, but I will have plenty of time to call the cops on him later if he cheats me, and I feel like the deal is good enough to warrant some risk. Even if all I get is the tank, at $120, I’ll be doing okay.

I’m not totally sure of the best way to weld old wrenches to stainless. The steel in wrenches isn’t exactly stainless, but it’s not plain old mild steel, either. It looks like stainless when you saw it and grind it. My plan is to use bits of stainless in my projects using tools like wrenches, so I’m going to use pure argon and see what happens. My guess is that it’s better to use argon and stainless wire with stainless and wrench metal than it is to treat everything like carbon steel.

I think the idea of making stuff from scrap is a very good one. I don’t come up with legitimate welding projects very often, and welding is not something you can do once a year and expect good results. You really need to do it more than once a month in order to avoid horrible results.

I’m 65% sure the information I provided here is right, but in any event, it should be a good start for anyone who wants to weld stuff other than carbon steel. If you read this post, you will definitely be better off than I was a month ago.

I do hope the Craigslist guy doesn’t kill me and take all my stuff. That would spoil everything.

More

I decided to do what I should have done before writing this: I Googled wrench steel. I learned that the “chrome vanadium” stamps on wrenches aren’t just advertising hype.

Good wrenches are made from steel to which chromium and vanadium have been added. This makes them more corrosion-resistant than ordinary steel, and it also gives them all sorts of structural strength. You can actually make springs from it. This steel can be hardened to Rockwell 55, whereas you would generally expect a good knife to be around 58.

Stainless steel has to have something like 10% chromium, and chrome vanadium comes in at about 1%.

People on the web say it’s a good idea to preheat it when welding it.

Hope this is useful or at least interesting.

Even More

The gas guy (He should put that on his business card: “Call and I will give you gas.”) arrived with my tank. I’m awestruck. It’s a newish tank, complete with argon sticker and safety cap, full of argon. A new tank, all by itself, runs $350, so I feel like I got a crazy bargain.

Let’s hope there is real argon in it when I open it up.

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