How To Cut Cast Iron Pipe

Do you want to make some repair in your house and wonder how to cut cast iron pipe? If you live in an old house, chances are that you will encounter these pipes often as cast iron was the preferred plumbing material in the past. If you are used to working with plastic pipes, you will require more expertise to cut cast iron. This guide discusses the various tools and techniques required to make your DIY project a success.

Preparing for a cut:

To begin with, you need to mark the line where you need to cut the pipe. For circular cuts, wrap a notebook or printing paper around the pipe, then trace the edge using chalk. You may need to tape two papers together for wider pipes. Use a straight material to mark along the pipe surface if you want to make a splice.

Ensure the pipe is adequately supported before cutting. For exposed horizontal sections, use pipe hangers to support the run at least every five feet. Use riser clamps for support at each end of vertically inclined pipes. Wear protective glasses and earplugs.

Method 1: Using the Reciprocating Saw

 A reciprocating saw is the preferred option for cutting cast iron as it does so with ease. Additionally, reciprocating saws work well in tight spaces where most other cutting tools cannot fit. Always be cautious when using this tool as it has an exposed, reciprocating blade driven by a powerful motor.

To cut a cast iron pipe, align the blade with the marked line and start the machine. Maintain average blade speed to prevent it from burning out. The catch is to use the scroll saw with a diamond blade as it is harder than cast iron. A carbide-tipped blade is also a good alternative. Adding some water to the blade is necessary to avoid overheating.   Consider cutting from one side to achieve a smooth cut if space allows. Cutting from multiple directions introduces unnecessary bumps.

Are you now comfortable with how to cut cast iron pipe? At least you should be good to go with a reciprocating saw.  You can use short blades for small diameter pipes and larger ones for the really big pipes. However, controlling reciprocating saw blade gets complicated with longer blades.  Applying some pressure to the saw should help you cut faster. Reciprocating saws create some dust when cutting on cast iron but this should not concern you as all dust falls to the ground.

Pay attention when shopping for reciprocating saw blades as they have different teeth per inch. For thick metals such as cast iron, use an 8-TPI blade or anything close.  Higher numbers such as 20-TPI blades are designed for cutting thin metals.

Method 2: Hacksaw

If for any reason you cannot access a reciprocating saw, you can use a hacksaw to cut through cast iron. Wondering if a hacksaw is too weak for cast iron? Well, you must be prepared to use several replacement blades and considerable energy.   Also, ensure the pipe is accessible from all sides as cutting from one end is not practical. This limits the use of a hack saw for cutting pipes in the soil.

As with the reciprocating saw, using the right hacksaw blade can make your work a lot easier. Regular set blades have their teeth set to the left and right alternating. Avoid these as they are meant to cut softer metals. Raker-set teeth are a good option for cast iron. You can identify these blades from their distinctive three-tooth sets

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Hacksaws either have fixed or adjustable frames. Fixed frames only accept one blade length while adjustable frames accommodate varying lengths. While adjustable frames have higher price tags, their versatility is worth the price.

To cut, secure the blade firmly on the frame with the teeth pointing forwards. The blade must be rigid and properly aligned with the frame for good results. Utilize the entire length of the blade in each stroke with the stronger strokes directed away from you. Cut slowly to avoid overheating and apply some oil to reduce friction.

Method 3: Snap Cutter

A snap cutter is another hand-held tool commonly used to cut cast iron pipes. Although you may not have one at your home, a snap cutter is quite affordable and easy to use. You will notice that the tool has a chain and a ratchet or scissors-like handle on which force is applied. Some models come with an adjusting screw for extra control. Place the roll-chain loosely around the pipe ensuring there as many cutting discs are in contact with the pipe as possible. Leaving excessive space between the first and last disc is a sure way of producing poor quality cuts.

After positioning the chain, apply pressure on the ratchet to cut the pipe. You may need to score the pipe before applying the final cutting pressure. As cast iron pipes are unusually tough, release the pressure and rotate the chain a few degrees. Apply pressure once more and check if the chain intends the pipe. Repeat this process until you make progress, then apply enough pressure for the final cut. The pipe should now snap into two.    Snap cutters produce clean cuts like a saw if used well.

Note that it will be difficult to make a clean cut if the discs of the snap cutter become flat. Increase the life of the cutter by reversing the chain to use all discs for cutting. The mechanical features of a snap cutter require proper maintenance to keep the tool in good working order.

Conclusion

There are many tools for cutting cast iron pipes but the reciprocating saw is the most versatile. Reciprocating saws can cut through tight spaces and even pipes in the soil. Additionally, they require no significant time to set up and produce negligible dust. Hacksaws are cheaper alternatives but are tiresome to use.   Only consider a hack saw for cutting cast iron as the absolute last resort. Snap cutters are effective but too heavy to maneuver. You may require some practice before figuring out how to balance the chain. All said choice for a cutting tool will depend on budget, available working space, and personal preferences.   Choose one today to complete your project in style.