Flamecutting and Grinding!

I learned two exciting new skills in my welding class yesterday, flamecutting and grinding. 

Flamecutting is certainly interesting. At times a bit more scary than fun. Basically, you have a nozzle with 9 holes, eight on the outside and one in the center. The outer 8 are for preheating, and the center one is for the actually cutting. The center hole is only used when you depress a lever on the side of the nozzle which I believe completely opens up the path for oxygen, which saturates the flame with oxygen making it very hot but also making it such that it will oxidize the steel. With flamecutting, however, this is not a worry because you are removing all of the steel that contacts the oxidizing flame.

The removing part is where it gets exciting. After preheating the steel up to about a yellow hot, you depress the lever and the flamecutting flame comes out and it is hot enough to instantly melt the steel, and the pressure from the gas from the nozzle shoots the melted metal away in a shower of sparks. Where do these sparks go? Why, directly away from the nozzle, of course. It's because of this I've learned to always try to flamecut away from yourself. Also I've learned to always have your pants over your boots, to avoid having hot pieces of metal fall into your boots and sit their for a while burning you.

It gets better, though.  Sometimes you have what's called a blowback, where instead of going away from you, pushed by the gases of the nozzle, the melted metal explodes outwards in all directions, and often makes an extremely loud and sudden popping noise. My guess is that this is caused by a pocket of air in the metal that, when heated up to quickly, explodes, causing the metal to behave much like several thousand degree hot liquid popcorn. This happens most of the time if you try to flamecut over an area that has already been cut. This is a tempting thing to do, as occasionally, if the part of the metal that was just cut stays too hot, the steel will fuse back together. 

And, just to add to all this, it's really hard to keep yourself steady if, like me, you're naturally a shaky or trembling person. This causes all your cuts to turn up looking like tiny zig-zags.

But, thankfully, this is why we have grinding tools. After having done a good bit of flamecutting, we were introduced to the 4 and a half inch grinders. These are somewhat crazy power tools that you plug into the wall, and when you turn it on, it will spin a 4.5 in. diameter disk really fast, fast enough to create a nice breeze, which you then put up against steel. What happens then is that some amount of steel is converted into a 15-foot jet of sparks. Yes, 15 feet, and, Yes, a jet. And these aren't all harmless little sparks, several of the things that shoot off the grinder are decent sized particles of hot steel. Luckily, most of the time, this just is facing away from you, though, depending on the side of the grinder you use, it can be facing you, and there are always little bits that get whipped around and towards you. The little devils get everywhere too. They've been known to light clothing on fire, light paper nearby on fire, and even bounce their way under your safety glasses and into your eye. Again, I try to avoid sending the stream in my direction.

This grinding, however, is extremely useful. When flamecutting, you'll often accumulate little beads of melted metal that are blown onto the sides of the steel. These little beads are no longer steel but are rather, because of the oxidizing flame I mentioned earlier, slag. The grinder is great for getting them off. The grinder also can smooth down the rough edges that all your trembling makes while flamecutting. Even more, the grinder can polish the metal and expose bright shiny bits under the black oxide coating, making the steel look a lot nicer. 

I think I can look forward to a lot of grinding in my future.