Cutting a steel pipe or tube

[Scott Felicetti]

I have a steel mold 12" in diamter 10" high. I want to cut it half from top to bottom leaving me with two half circles. (not cut it half to give me two 12" diameter circles 5" high). Because of the size of the object I can't cut it on my mitre saw with a metal cutting blade. Any simple solution besides taking it to a metal shop monday morning. I will have to make to cuts opposite each other to get two half circles (or half cylinders).
Thanks in advance for any suggestions.

[Bruce Gray]

I think that I would try a circular saw with an abrasive metal cuttting blade. A 4-1/2 angle grinder with a metal slitting blade would be another option ...that could be done with a 1/16" kerf blade.

I'm assuming here that the metal has a pretty thin wall.

Bruce

[Cliff Rohrabacher]

I have a steel mold 12" in diamter 10" high.

Mold??
As in Injection mold?
Weighing near a hundred pounds or so?

Or like a Jello, chocolate, or cake mold used in a kitchen?

What exactly do you mean by "mold"?

[Scott Felicetti]

I'm assuming here that the metal has a pretty thin wall.

Bruce

The wall thickness is 1/3". Is this too thick to reasonably get through with a circular saw? Tips on getting the cut line to be straight?
thanks,
Scott

[Scott Felicetti]

Mold??
As in Injection mold?
Weighing near a hundred pounds or so?

Or like a Jello, chocolate, or cake mold used in a kitchen?

What exactly do you mean by "mold"?

What I call a mold, started out as a pipe. Just think of a 12" diameter pipe. For sewage or plumbing. The pipe is made from steel with a 1/3" thick wall. The height of the 12" diameter pipe is 10". What this really is is a section of a large pipe. But it's still a mold to me because I use it as one.
Scott

[Carl Crout]

1/3" that's pretty thick. You might could cut it with a cutoff wheel in either a 4" grinder or a air cutoff tool but with that thickness you will be there a while - As well as wearing out multiple wheels.
A welding shop could cut it fast with a plasma cutter and probably cheap.

[David G Baker]

Scott,
Visit your local machine shop or welding shop if you want accuracy and a quality cut. It may surprise you that the price may be reasonable as well. If you mess up on cutting the pipe yourself it won't be cheap to replace.

[Mike Parzych]

That's not just run of the mill steel that you've got. Probably P-20 or some such other hardened tool steel. Abrasive cutting will only work harden it as the heat increases. And it's not going like any of the common band saw type blades.

Take it to a tool/die shop - it'll be worth it.

[Ken Werner]

I don't know much about cutting metal. But I'd try a sawzall. You didn't say how accurate your cut has to be. If it has to be spot on, then seems to me, a pro shop is in order. Others here know more than me.

Ken

[Scott Felicetti]

Thanks guys. I think the verdict is let a pro do it. I do need an accurate cut, so I will hit up the local machine shop/welding shops in my town in the morning.

[David Micalizzi]

I routinely work with steel being a pipe fitter and welder among other things at my day job. When I can't bring the work to the saw or there is product (Read Asphalt) in the pipe that prevents torching or other methods, I at times cut steel with an angle grinder and abrasive cut off wheel. The key to having this work quickly is a thin kerf wheel. There are different size cut off wheels find a thin one. However, either would work in your case. You don't say how accurately you need to make this cut. If I have to make a super accurate cut I set up some type of guide. Not ussually the case because most of the time I just grind the cut close to what I need and then weld fills in the rest. You could clamp a piece of angle iron or some other straight edge to the pipe and use this as a guide. Even if you do this there probably will be some clean up work after your done cutting. Getting two halfs the exact same chord length will not be easy either, but doable. If in needs to be perfect a machine shop is probably your best bet. I'm not saying you can't do it yourself, it just might take you a long time grinding to get the halfs to match each other. If they just need to be close it should not be that hard.

[Ray Knight]

a big piece of pipe is likely not high temper, if you can scratch a corner with a hacksaw, then it can be cut fairly easily. Find a friend with a metal stand band saw, align it, clamp it in, drop the cutting top down, sit back and have a cup of coffee and it will be done. You could get through it with an abrasive wheel on a grinder, but it would take forever, consumer $10-20 of grinder wheels, and could be dangerous if you get the wheel bound, I would cut something that big with a grinder. My prior hobbies have been auto restoration and metal fabricating, so this is down my prior alley, this woodworking stuff is what is new to me. check that it's not hardened, which it won't be, then get a friend with a stand type band saw, buy him a 6 pk (but don't drink it until you are done). If you live close to Louisville, Kentucky or southern Indiana, I can help you with it. Ray Knight

[Matt Meiser]

A plasma cutter should cut it pretty quickly and leave a decent edge that you can clean up quickly with a grinder.

[Cliff Rohrabacher]

What I call a mold, started out as a pipe. Just think of a 12" diameter pipe. For sewage or plumbing.

I suspect this is a cast iron pipe section.

Scribe a line around the diameter ( or whatever your cut path is).

If it is Cast Iron you can cut it with a hack saw, a saws all with a metal blade, a jig saw with a metal blade, or an abrasive metal blade in a hand held circular saw. Cast iron cuts like butter.

The pipe is made from steel with a 1/3" thick wall. The height of the 12" diameter pipe is 10". What this really is is a section of a large pipe. But it's still a mold to me because I use it as one.
Scott

If it's really steel (& not cast) it's probably hot roll with a welded seam. You can cut that with a saws all just, or an abrasive metal blade in a hand held circular saw. In either case It'll take a couple of blades. Run a saws all on slow and use any oil and an acid brush to lube the blade and just follow your line.

[joe greiner]

But it's still a mold to me because I use it as one.

Bear in mind that, however it's cut, it will no longer be perfectly circular inside. The short diameter will be reduced by the amount of the kerf from cutting. You may need to revise the design of your molded article to account for this, or accommodate it in some other way, such as adding shims to replace the cut-away material.

Joe