What is a Hacksaw?

A hacksaw is a manual cutting tool made up of a rigid, U-shaped frame, a comfortable handle, and a narrow replaceable blade stretched under tension. The blade’s tiny teeth (measured in teeth per inch, or TPI) are designed to cut on the forward stroke, which helps it slice cleanly through metals like steel, copper, and aluminum, as well as plastics such as PVC and ABS. Because the blade is thin and held tightly, a hacksaw makes straight, controlled cuts without requiring power.

Common DIY Uses

Hacksaws show up in many home projects, especially where clean, controlled cuts in small stock are needed:

Cutting copper pipe for sink or toilet supply lines
Trimming PVC or ABS for drains or sprinkler repairs
Cutting EMT conduit for electrical runs
Shortening threaded rod for shelving, water heater straps, and fixtures
Removing rusted bolts and nails during repairs
Cutting angle iron, aluminum bar, or steel brackets for custom hardware
Trimming metal closet rods or curtain rods to fit

If you’re doing light plumbing, electrical work, or small repairs, a hacksaw is often faster to grab and quieter than a power tool.

Types and Blade Options

While the basic idea is the same, you’ll find several variations:

Standard adjustable frame: Accepts 10- or 12-inch blades (250–300 mm). Good all-around choice.
High-tension frame: Stiffer, with a tensioning mechanism that keeps the blade very taut (often up to 30,000 psi). Reduces blade wander for straighter cuts.
Mini or compact hacksaw: Short frame and handle for one-handed use in tight spaces, like under sinks or near walls.
Junior hacksaw: Uses a smaller, thinner blade (typically 6 inches). Handy for very tight quarters and thin material, though slower on larger stock.

Blade choices matter as much as the frame:

Bi-metal blades: Flexible body with hard cutting teeth. Durable and less likely to snap—great for general use.
High-speed steel (HSS): Very hard teeth for long life, but more brittle.
Carbon steel: Affordable, good for softer metals and plastics, but dulls faster.

Common blade TPI options and uses:

14 TPI: Thicker material and softer metals (e.g., thick aluminum, large bolts)
18 TPI: General metal cutting (angle iron, pipe)
24 TPI: Everyday pick for mixed metal work and plastic
32 TPI: Thin-walled tubing and sheet metal

Rule of thumb: Keep at least 2–3 teeth in contact with the material at all times. Thinner stock needs higher TPI to prevent snagging.

How to Choose a Hacksaw and Blade

Consider these features for a smoother experience:

Frame stiffness and tension: A high-tension frame tracks straighter and reduces chatter.
Comfortable handle: A soft-grip or ergonomic handle reduces fatigue on longer cuts.
Quick-release mechanism: Speeds up blade changes.
Blade rotation: Some frames let you rotate the blade to 45° or 90° for flush or awkward cuts.
Blade storage: Built-in storage in the frame is convenient.

Choosing a blade:

Material: Use bi-metal for general work; switch to HSS for frequent metal cuts; carbon steel for plastics and occasional use.
TPI: 18–24 TPI covers most homeowner needs. Keep a 32 TPI blade for thin tubing and a 14–18 TPI for thicker sections.
Length: 12-inch (300 mm) blades are standard and widely available; match the blade length to your frame.

How to Use a Hacksaw (Step-by-Step)

Mark the cut: Use a pencil or marker. For square cuts on pipe or rod, wrap masking tape around as a visual guide.
Secure the work: Clamp the material in a vise or use clamps on a bench. Stability makes the cut straighter and safer.
Install and orient the blade: Teeth should point away from the handle so they cut on the forward stroke. Tension the blade firmly.
Start the kerf: Place the blade on the mark and draw a few light strokes back to create a shallow groove. This guides the cut.
Saw with full, steady strokes: Use long strokes that engage most of the blade. Apply moderate pressure on the forward stroke; ease up on the return.
Control speed and heat: For metal, steady pace beats brute force. A drop of cutting oil reduces heat and extends blade life.
Finish and deburr: As you near the end, reduce pressure to avoid snapping off the last bit. Smooth the cut edge with a file or sandpaper.

Tips:

For small round material, start the cut at a shallow angle until the blade seats, then level out.
Use a miter box for square or repeated cuts on rod or pipe.
For thin-walled tubing, use a higher TPI and light pressure to prevent grabbing.

Maintenance and Care

Blade care: Replace dull or missing-tooth blades promptly; a fresh blade is safer and cuts straighter.
Tension: Release tension when storing the saw to reduce stress on the frame and blade.
Cleanliness: Brush off metal filings and wipe the frame. A light coat of oil helps prevent rust.
Storage: Keep spare blades in a sleeve or tube to protect teeth and prevent corrosion.

Mistakes to Avoid

Wrong blade orientation: Teeth pointing toward the handle cause poor cutting and blade chatter.
Using the wrong TPI: Low TPI on thin stock snags; high TPI on thick stock cuts too slowly and overheats.
Low blade tension: Leads to wandering cuts and broken blades.
Overpressure: Pushing too hard overheats the blade and dulls teeth faster.
Not clamping the work: Movement causes crooked cuts and increases risk of injury.
Twisting the blade: Keep strokes straight; side-loads snap blades.
Cutting hardened steel: Some hardened fasteners resist hacksaw blades—use an angle grinder or specialized tool instead.

Related Tools and Terms

TPI (Teeth Per Inch): Measure of tooth density on the blade; higher numbers mean finer teeth.
Pipe cutter: Wheel-based tool for round pipe; leaves cleaner, square edges on copper and some plastics.
Reciprocating saw (Sawzall): Power alternative for faster cuts in metal and wood; less precise without guides.
Coping saw: Hand saw with a narrow blade for intricate curves in wood and plastic—not for metal stock.
Bow saw: Frame saw for wood; larger teeth, not for metal.
Miter box: Guide that helps achieve accurate square or angled cuts with a hand saw.

Real-World Examples

Under-sink copper repair: Shut off water, mark the pipe, clamp or brace it, and use a 24 TPI bi-metal blade. Deburr the cut before installing a compression fitting.
Shortening threaded rod: Thread two nuts onto the rod past the cut line, saw with an 18–24 TPI blade, then back off the nuts to clean the threads.
Trimming a metal closet rod: Use a miter box and 24 TPI blade for a straight cut. File the edge and cap it to protect clothing.
Removing a rusted bolt: If the nut is seized, saw through one side of the nut with a 24–32 TPI blade, then split it off with a chisel.
Cutting PVC for sprinklers: Mark, saw with a 24 TPI blade using light pressure, and chamfer the edge slightly for a better glue joint.

With the right frame, a suitable blade, and good technique, a hacksaw delivers clean, predictable cuts on metal and plastic—without sparks, noise, or a power cord.