Cutting cast iron pipe


I have a 3" cast iron vent pipe that I need to cut in order to rework some plumbing. I used a sawzall with a cast iron blade by Lenox and was able to cut through it after about 5 minutes. Unfortunately I did not start the cut evenly (it is a vertical pipe so I must have held it not perfectly horizontally) and the cut was a bit slanted. I noticed it after the cut was half way but I have no choice but to continue and get through the cut. Now the high end is about 5/8" higher then the low end.
I plan to use a no hub coupling to join with a PVC pipe, and I do not want the gap to be more than 1/4" since I might one day need to snake the line and I don't want a cutting head to slide through the 5/8" space and end up cutting the no hub rubber sleeve even if I have a metal shield outside I rather get the cast iron cut end to within 1/4".
I have two choices - to do a new cut and this time try to cut it evenly, but I am very close to a sanitary tee if I mis-cut again I will have to replace that too...or I can use an angle grinder to grind the edge even, but I am wondering can I really use a metal wheel to grind even a 3" CI pipe that is 5/8" off?
Thanks in advance for any advise,
MC
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MiamiCuse wrote:

Grind, probably not, but if you draw a reference line in chalk and use a cutoff wheel in the angle grinder you should be able to do it.
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I think this idea has merit. You might experiment with the chunk you cut off, but I suspect that if you were to score the pipe you might even be able to snap off the bit you want to discard.
You might use the cutoff wheel on the OD of the pipe scoring it to a depth of aprox. 1/4 the thickness and then use a smaller dremel type cut off wheel to score the inside. Scored in this manner, the pipe should crack along the line. You might also make a few cuts to the line from the edge.
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Go down to your tool rental store and get a big autobody type 7" grinder with a 50 grit pad. It will take the 5/8" misfit down in about 5 minutes or so. The typical angle grinder just doesn't have the cojones to do what you need. You probably heard your Grandad say, "You can't drive a spike with a tack hammer" so take that advice to heart.
Joe
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If you own a small angle grinder, 4-5", get a few weld cutting disks. They will zip through the cast iron and a fairly easy to control.
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