How to Cut Cast Iron Pipe

I don’t own a “pipe snapper” to cut cast iron. So my favorite tool for that nasty job is a grinder equipped with a diamond blade. In tight spaces where my grinder won’t go, I’ve always used a reciprocating saw and metal-cutting or carbide-grit blade. That works, but not very quickly. And cast iron destroys blades fast; I’d go through two or three blades cutting a 4-in. pipe.

So recently, I tried a diamond recip saw blade. There are various brands, costing $10-20 each at home centers. I used a Lenox 9 in. version that has tangs on both ends, so you can switch ends when one section of the blade gets dull (brilliant!). Here’s what I learned:

• The blade cut faster than carbide grit or metal-cutting teeth, but not nearly as fast as a diamond grinder blade.
• It didn’t dull. Even after two 4-in. pipe cuts, it continued to cut without a noticeable slowdown.
• It didn’t break. Working in a cramped spot, I bent the blade a dozen times. Big, bad bends. To my surprise, it didn’t break.
• Bonus: It didn’t set off nearby smoke alarms, as my grinder usually does.

Bottom line: The grinder will remain my first choice for cast iron. When that’s not an option, I’ll grab a diamond recip blade.

— Gary Wentz, Editor in Chief