How to cut cast iron pipe

Because cast iron comprises of more carbon content, it’s tougher than even steel to cut.

Subsequently, tools that cut through steel like a hot knife through butter including a circular saw struggle mightily when used on cast iron piping where its part of a home’s plumbing system.

This begs the question: what exactly is the best and fastest way to cut cast iron pipes?

Well, this article will show you how to cut cast iron pipe easily and quickly.

Let’s dive in:

How to cut cast iron pipe – tools and step by step instructions

With the correct equipment and proper know-how, cutting cast iron pipes may not be as daunting as you imagine.

Below we take you through the devices you can bet on when it comes to slicing through cast iron pipes and how to use each in a DIY plumbing project.

How to cut cast iron pipe using a snap cutter

A snap cutter is a favorite of professional plumbers and for good reason: it breaks cast iron’s resistance in no time.

Moreover, the device – it features a ratchet along with a length of roller chain- almost always makes a sleek smooth cut.

Instructions

  1. With chalk (or a crayon), mark the cut lines on the cast iron pipe. Be sure to keep the lines straight.
  2. Next, wrap the piece of chain on the snap cutter such that it goes around the pipe.

Tip: Since the idea is to have the chain exert even pressure on the pipe, ensure that there are many cutting wheels (as many as you can) touching the pipe before moving to step 3.

  • Start to press onto the tool’s handles to make the wheels – embedded in its chain- bite into the cast iron pipe.
  • Keep increasing the ratchet pressure until the pipe snaps.

See?

The tool is incredibly easy to use.

Plus, it gets the job cheaply as you can hire one from a tool’s rental center instead of burdening your wallet with a one-off tool (yet again!) that you’ll rarely use.

How to cut cast iron pipe with an angle grinder (also disc grinder or side grinder)

If there’s a tool you can trust to be a jack of all trades (and a master of everything), it’s the angle grinder.

From cutting tiles, stucco, and pavers, to routing out mortar, an angle grinder can do it all.

The grinder is also cuts cast iron pipework installed on mains drainage, sewer pipe applications, etc. at warp speed.

How Does It Work?

Paired with the appropriate cutting wheel, the sturdy angle grinder cuts just about any tough-as-nails metal you throw at it.

Specifically, you need to fit either a great cutoff wheel, or a beast diamond wheel to your angle grinder to have it eat into cast iron like nobody’s business.

Instructions

Like with a snap cutter, an angle grinder is easy-peasy to use to cut cast iron.

Here is how to cut cast iron pipe with this amazingly effective monster:

  1. First, mount your favored metal cutting disc or a diamond wheel to the angle grinder.
  2. Mark the pipework you want to cut as outlined previously.
  3. Place the cast iron pipe on a safe working place, for example, a workbench. Make sure the pipe is adequately supported before proceeding.
  4. Start the grinder and cut all around the pipe’s circumference. You can first cut through one half then turn the pipe and cut through the other half until the pipe splits into two.

Tip: Power tools like angle grinders can be hazardous and it’s important to put on your protective gear – work gloves, eye, and ear protection, etc.- before getting down to business.

How to cut cast iron pipe with a reciprocating saw

From my experience, nothing beats a reciprocating saw (or Sawzall) as far as cutting cast iron piping is concerned.

All you have to do to have it cut cast iron quickly is add a top-rated diamond reciprocating saw blade (like this) to your recip saw.

There’s always a chance that a snap cutter will crush the pipe or leave ragged, uneven edges but with this, you’re guaranteed an extremely smooth and clean cut all the time.

Instructions

  1. Outfit the saw with the cutting blade. 
  2. Next, mark the cut lines on the pipe as explained earlier. 
  3. Hold the pipe – or ask a friend to help you- firmly in place.
  4. Start sowing the pipe at low speed until it yields.

Tip: Do not press hard on the saw as unrestrained pressure can break the blade.

Cutting cast iron pipe with oscillating tool

An oscillating multi-tool tool is tremendously versatile and excels even on cutting cast iron.

Okay, it may probably take a bit longer but it works where its rivals would be a nightmare including tight corners and the narrowest of spaces. 

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How Does It Work?

An oscillating multi-tool tool accepts a sea of accessories depending on the job.

For this, simply equip it with a multi tool blade that handles cutting cast iron pipes (check this example) and you’re good to go.

The blade cuts cast iron pipe as the tool vibrates back and forth (the tool actually oscillates back and forth though it feels more of a vibration at high speed).

Instructions

  1. Attach the blade.
  2. Mark straight cut lines on the cast iron plumbing pipe (you already know how).
  3. You then lightly carve out a very shallow groove along these lines (don’t push the tool much at this stage).
  4. Now you can start pushing harder –on the groove- while still trying to maintain a straight cut.
  5. Keep at it until the pipe breaks.

Wrapping it up

Whether you want to do some emergency plumbing repairs or complete a long-overdue upgrade to PVC, you have to come up with a smart way to cut cast iron pipes.

You’re now aware of the right tools and the step-by-step procedures.

Choose the equipment and the technique that appears friendliest to you and make mincemeat of the otherwise stubborn cast iron pipes.

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