Oxy cutting a 8" steel shaft

We need to cut a 8" steel shaft (crankshaft on a punch press) to safely take off the flywheel before dropping down the whole press.
How can I do it with O/A? Tip size? Can it be done with 315FC torch?
i
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I would not try that with acetylene. I don't like taking acetylene past 2" thickness.
I would go to a 100 lb. propane tank with an acetylene regulator. You will also want a 240 or greater oxygen bottle with a high flow regulator, and 3/8" hoses or your torch will choke.
The victor 315 torch is fine, but buy a #8 propane tip for it.
Run the propane at 5 psi and your oxygen at 100-125 psi. Your oxygen regulator will freeze up if it can't handle high flow rates. If the output gauge on your oxygen regulator goes up to 200 psi then it is rated at 100 psi max output. You might be able to rent a high flow regulator.
To light propane: Crack the fuel gas valve Crack the oxygen valve Rest the torch tip against a piece of steel at a 45 degree angle and use your spark lighter to ignite the mix. Now increase your fuel and oxygen in stages until your fuel gas is maxed out and the flames have pulled back to a short LOUD pale ring of flames.
The main reason people have had bad experiences trying to use propane is that they treat it like acetylene. That won't work.
Also keep the tip about 3/4" from the steel for optimal cutting. If the tip gets clogged in the center from a blow-back, then use a tip cleaner, but if the flame jets get dirty remove the tip and separate the core from the outer shell. Then wire brush it and reassemble.
In general propane tips will last about 4 times as long as acetylene tips.
Propane and the other LP gasses are far better for cutting heavy steel than acetylene because their hottest point is much further from the tip. The heat will carry further through the steel.
For an 8" shaft you will have to travel very slowly in the center to make sure you get a clean cut, and massive amounts of molten steel will be flowing out the bottom of the cut. I once cut a 700 lb. anvil from 6" plate steel. It took 30 minutes and drained an oxygen bottle. Mind you I was using a pattern cutter.
I have cut up to 10" steel with propane. It is the most common gas used in scrap yards and big burning shops.
It would be best to practice on a hunk of scrap steel to get your travel speed down.
Good luck.
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On Wed, 23 Apr 2014 19:03:47 -0700, Ernie Leimkuhler

In the scrap yards around here they dispense with the oxygen tank and run with compressed air - compressor on the big Michigan loader which is generally always nearby anyway.
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I seen this and tried it for myself. Couldn't get it to work well for cutting. You've got 22% O2 instead of 100% O2
propane over compressef air is a tiny fraction of the cost of acetelene over oxygen.
Karl
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All the "field scrappers" around here who break down large assemblies in- situ use oxy-propane. TONS cheaper than oxy-acetylene, and cuts most steel very effectively.
The big problem Ig has is trying to cut that long a kerf. With enough gas velocity, he might get the kerf 2" deep across the width of that big shaft, but he'll have to 'wedge cut" sections out in order to get the torch close enough to cut near the middle.
Most any-sized torch could do that if it's only hot enough to start cutting, AND you have the time and gas to do it.
LLoyd
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Thanks, Ernie. I bought some biggish tips and I will try tomorrow.
i

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On 4/23/2014 8:13 PM, Ignoramus18845 wrote:

Can't you take it apart? I've had the flywheels off of all my presses, granted none are that big but the process is the same.
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