Over fifteen years of running nine rental units on my own, I’ve snapped more cheap hacksaw blades than I can count, usually because I grabbed whatever was sitting in the toolbox instead of checking the tooth count first. The blade that powers through a rusted metal drain trap is not the blade you want anywhere near a PVC waste pipe, and mixing the two up costs you time, a wrecked blade, and sometimes a cracked fitting that now has to be replaced for around 800 yen instead of just cut once cleanly. This is the exact system I use to pick the right blade before every job, whether I’m cutting galvanized pipe in a 1980s unit or trimming PVC conduit behind a new outlet box.
Why Blade Choice Matters More Than the Saw Itself
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Every hacksaw frame looks basically the same, so new landlords assume any blade will do. It won’t. Metal and PVC behave completely differently under a blade. Metal is hard and rigid, so it needs fine, closely spaced teeth that shave off small chips without snagging. PVC is soft and low-melting, so fine teeth just clog with plastic dust and heat up from friction until the pipe starts to gum and bind around the blade. I learned this the hard way on an early job, trying to cut a 50mm PVC drain with a leftover metal-cutting blade. It took nearly 5 minutes of fighting a melting, binding cut instead of the 90 seconds it should have taken with the right blade.
Teeth Per Inch (TPI) Is the Number That Decides Everything
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The spec that matters most on any hacksaw blade package is TPI, teeth per inch. For metal, I reach for 24 to 32 TPI depending on wall thickness. The rule I follow is that at least 3 teeth should be touching the material at any moment during the cut; go coarser than that on thin conduit and the teeth catch on the edge and snap off within a couple of strokes. For PVC and other plastics, I drop down to 14 to 18 TPI. Coarser teeth clear the kerf faster, cut cooler, and don’t give the plastic time to melt and re-weld itself around the blade as you push through.
Cutting Metal Pipe, Conduit, and Old Fasteners
Most of the metal I cut across my properties is galvanized steel pipe with a wall around 3.5mm, plus the occasional rusted bolt or seized shower valve stem. For standard pipe I keep a 24 TPI bi-metal blade loaded and it will get me through 6 clean cuts before the teeth noticeably dull. For thin conduit or stubborn rusted hardware, I switch to a 32 TPI blade, since the finer teeth resist snapping on the harder, uneven surface. I once tried forcing a 32 TPI job with an old 18 TPI blade left over from a plastic job, and it broke two teeth in the first two strokes on a rusted valve, which tells you how quickly the wrong TPI ruins a blade.
Cutting PVC and Plastic Drain Pipe
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PVC waste and vent pipe is the most common plastic I cut, usually in 50mm and 75mm diameters. An 18 TPI blade, sometimes a dedicated plastic-cutting blade, clears the cut in well under 90 seconds with light, steady strokes rather than heavy pressure. Pushing hard generates heat, and heat is the enemy here, since it melts the cut edge into a rough, slightly rounded lip that never seats cleanly into a fitting and can leave a joint prone to leaking later. Slower, lighter strokes with a coarse blade give a crisp, square edge every time.
A Quick Checklist Before You Buy
Whenever I restock my blade supply, I run through the same short list so I don’t end up guessing on site:
- Identify the material first: steel, copper, aluminum, or PVC/plastic
- Check wall thickness; thinner material needs a higher TPI
- Match TPI to material: roughly 24 to 32 for metal, 14 to 18 for PVC
- Choose a bi-metal blade if a job mixes both materials in one visit
- Keep at least 10 spare blades in the supply bin, split evenly between the two TPI ranges
- Swap the blade once teeth look visibly dull, usually after about 15 cuts
My Go-To Blades for Rental Maintenance
I buy standard 12-inch, 300mm blades in combo packs, which usually work out to somewhere between 250 and 350 yen per blade. I keep two labeled boxes in my van, one for 24 TPI metal blades and one for 18 TPI plastic blades, so I never have to guess mid-repair, and so any handyman I hire for a day grabs the right one too. That small bit of organization has saved me more blades, and more frustrated afternoons, than any fancy power tool ever has.
That’s the approach I use across all 9 of my properties, and it’s the one habit I’d tell any new landlord to build first.
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15 years of landlord experience u00b7 3 apartment buildings u00b7 DIY renovations that saved millions of yen. Browse all articles at diytosan.com
