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oxygen cylinders into mandrels?


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Hi folks, could heavy duty oxygen cylinders be turned into decent mandrel cones? I've recently come to know a local fabricator that has all sorts of big boys toys and seems to be able to turn his hand to anything - boats, film sets, gates, farm machinery repair...
 
He has many redundant cylinders lying about and if the consensus is they'd be suitable then I'll suggest to him he could turn them into mandrels. Aside from the suitability are mandrels sought after much nowadays? Penny for your thoughts...
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Are you talking about cone mandrels? If so, I would be wondering about the way you would create a cone mandrel from an oxygen bottle. 

 

What they are very very good for, however, are gas forges! Use the bottom as a small dishing swage as well! 

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Since HP cylinders average 1/4 inch thinck along the side I would think it would be quite a feat to make a manderal.  You wouldn't be able to turn it.  This brings up a safety concern.  You need to make sure that the cylinder is completely empty.  Just because you turn the valve on and nothing comes out doesn't mean it is as the valves can break internally.  A guy I worked with almost killed himself devalving one that way.  It missed his head by inches.

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Assuming you've safely decommissioned the bottle, how you planning on forming it? I don't see a reason why not, it's good steel  and can be ballasted for stability.

 

Frosty The Lucky.

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Yeah, cone mandrels. The fabricator has already cut oxygen cylinders for me and I've used the bottoms as bowl sinking tools. I guess you'd need to cut the top and bottoms off, then cut a V shape out, then somehow compress it so the V is closed and you get the cone shape, then weld shut. Easier said than done though and I don't know what sort of machine could compress it to shut the V.

 

At another steel supplier/fabrication yard I came across an off-cut of twisted solid bar that was at least 1.5" square. I asked one of the guys there if he twisted it, he said no and pointed to a machine in the corner and said that it twists cold solid bar. My jaw hit the floor and since then I've thought that anything's possible.

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If it were me I would cut the cylinder in half length wise then make a tapering pie and weld it together. Hope that made sense.


That unfortunately would make an elliptical shape.
Cutting the v wedges out does work. I use to make cones out of two inch pipe to slide over anchor bolts. Sort of acted like a spud bar when setting the power poles.
That said I worked with two inch pipe which was cake compared to what you want to do.
Use a rosebud to bend em in. Its a doable project. Hope you have a good grinder.
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Yeah, cone mandrels. The fabricator has already cut oxygen cylinders for me and I've used the bottoms as bowl sinking tools. I guess you'd need to cut the top and bottoms off, then cut a V shape out, then somehow compress it so the V is closed and you get the cone shape, then weld shut. Easier said than done though and I don't know what sort of machine could compress it to shut the V.

 

At another steel supplier/fabrication yard I came across an off-cut of twisted solid bar that was at least 1.5" square. I asked one of the guys there if he twisted it, he said no and pointed to a machine in the corner and said that it twists cold solid bar. My jaw hit the floor and since then I've thought that anything's possible.

At a large steel mill, I was once shown a machine they claimed could cold roll 2-1/2 inch plate into a 30 inch cylinder in a single pass. Yep, those things are possible. For my grad school research, I had a vessel of about those dimensions (30 inch I.D. rated at 3000 psi)., but don't know how it was formed. It cost over $3000 in the early 60's, close to $30,000 in today's dollars. That's the vessel, not the roller.

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Possible but probably not cost effective as finding something already closer to shape---at one Quad State a fellow brought in a truck load of steel nose cones from Ballistic missiles.  Made dandy cone mandrels and at a very good price indeed $75 per

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What you are are proposing is a whole bunch of work and the results will be less than perfect.  The idea of a cone mandrel is to produce smooth round rings most likely what you produce will not be smooth and round.  It takes a lot of skill to to forge plate into a smooth and true cone.   Many very skilled smiths would flat out refuse to try what you are proposing for good reason.  Do you really even need a cone mandrel.  I have one and I am a full tome professional smith it gets used about twice a year.  More often than not I make a quicky form for the job at hand.

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It's not for me Timothy, he has half a dozen or more empty cylinders lying about taking up space so my point is he could salvage them into mandrels and sell them. If he did do it he wouldn't do it by hand, he's got a variety of machines for various jobs.

The reason I thought of mandrels is because I don't see many about, and I regularly chat to a guy who buys & sells blacksmiths tools & he said full size mandrels sell easily as they're kinda rare.

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Profit from a sale is what is left over after covering the costs of time and materials. If the steel is worth only scrap price, the cutting, forming and welding still costs money, and the results would only be a clover-shaped lobed bell, not a true cone.

 

Better to make bells from them, take the money, and buy a cone.

 

post-114-0-26128700-1368355373_thumb.jpg

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I don't know how cylinders are marked over on your side of the pond but here's a little info if it helps.  Cylinders marked with a 3A-XXXX (the x's are the pressure the cylinder is rated for) are manganese steel, the ones with a 3AA-XXXX are chrome moly steels.  The latter are the newest as it is stronger and can be made lighter.  Your not going to work them cold.  I believe carbon content is around .4 to .5%. 

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