How to Cut a Gas Cylinder With a Horizontal Bandsaw
Kevin is ready to give his Ellis 1800 series horizontal bandsaw its first real job. He's cut some small stuff with it, but now he needs to cut the end off a gas cylinder. (He's showing how he has it set up when Pokie the dog, uh, pokes her nose in.)
The cylinder is 5 feet tall, a 300 cubic foot compressed gas bottle, which probably held oxygen. Kevin is making a large, 3-armed sound sculpture, for which he'll need to prepare 3 cylinders, which make awesome bells. Now it's time to chop the end off the first one.
In the past, Kevin wrapped a broken sanding belt around the cylinder, matched up the ends, then used soapstone to mark a straight line around it. Then he'd use a plasma cutter to make the cut. Before he had a plasma cutter, he used a jigsaw - that took a while! Then he'd spend about an hour cleaning up the dross, grinding the edge to make it smooth and even.
It'll be interesting to see how straight and square and smooth this cut comes out - and how much time it saves, too.
One reason Kevin wanted this saw was because of its wide throat. He had to move the vise to accommodate the cylinder, and he could even make it wider to take advantage of the full throat, if he wanted.
The cylinder is held nice and steady in the vise, with a stand holding up the other end of the cylinder. He spent a few minutes on his knees making sure the cylinder was flat on the table simply by looking at where the cylinder is sitting on the saw and making sure it is touching evenly on both ends. He did that by trying to slide a piece of paper between the cylinder and the table in the front and back.
There are several reasons getting the cylinder level is important. First, you want a straight cut. Second, you don't want to trap the sawblade, which can happen if the cylinder is tipped down toward the saw. If you're going to err, have the other end of the cylinder a little lower, but, Kevin says, it's better not to err at all.
Now he's is ready to fire up the machine. Kevin guesses it will take about 5 - 10 minutes to cut the cylinder (it actually took about 30 minutes).
As the saw runs, Kevin explains that he is still learning how fast to run the feed, which is adjusted with a bleed screw. He knows the cylinder is about 1/4" solid steel wall, so he wants it to cut slowly so he doesn't overheat the blade.
The saw cuts through the cylinder slowly but steadily. As it begins cutting two walls at once, you can hear the sound change. Kevin says he can probably speed it up a bit. Meanwhile, he is a little concerned about whether he gave himself enough room to clear the dome in the bottom of the cylinder. He doesn't want to cut the cylinder any shorter than he has to, but he'd rather not hit that extra section, either. He says it should just clear it, or maybe slice off a little bit.
The saw is air-cooled, which is why Kevin is running it a little slow, rather than forcing the cut through. Nonetheless, he decides to open the feed about 1/16 of a turn. He points out that the sound changes a bit as he does so.
Kevin shoots the incoming area of the blade with his infrared thermometer and notes that it's about 81 degrees Farenheit. On the outgoing side, it's only 83-1/2 degrees. He decides to open it up a little more. The infeed rises to 91 degrees. He decides to slow it down - it may be hitting the dome - and it drops to 88 degrees. "Slow and steady," says Kevin.
Finally, the bottom drops off. The blade did cut through the top of the dome. The cut is sharp and very straight and smooth. Kevin is impressed with the job the saw did.
Although you might want to stick around for another moment to see Kevin greet a real stranger .....
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