Can You Hacksaw a Bolt, Screw or Padlock?

Short answer by item

A hacksaw is a good match for bolts and screws made of ordinary steel, brass or aluminum. It is a slower match for hardened fasteners, and a poor match for the best-protected padlocks.

The table gives a quick read. Treat it as a rule of thumb, since the metal inside the fastener decides how hard the job is.

Choosing the right blade

The blade matters more than the frame. Match the teeth to the metal, because teeth per inch (TPI) decides how smoothly the blade cuts. Several teeth should touch the work at all times, so a fine blade suits a thin screw or a small bolt.

Bi-metal blades pair a hard cutting edge with a flexible body, which helps them resist snapping. Many of the saws on our best hacksaw page use a 24 TPI bi-metal blade, and the KATA 10-in mini hacksaw lists that same blade type as suitable for metal rods, thin tubing and bolts. The same listing says it is not meant for thick hardened steel, which is a useful reminder about limits.

Not every saw that looks like a hacksaw will do the job. The Mossy Oak folding saw has three 7.5 in blades, but only the 18 TPI blade is meant for metal, and its listing rates that blade for thin copper or aluminum pipe. It is not a bolt cutter, so skip it for fasteners.

Choosing the right saw size

Full 12 in frames, such as the Hanpex, PLOWFAR and HAUTMEC models, give long strokes and list a 4 in cutting depth. That depth is plenty for a bolt, since you are cutting across a small diameter.

Compact saws help when a bolt sits in a tight spot. The Klein Tools compact hacksaw is 10 in long and lists a tool-free lever for blade changes at 0.5 lb. The KATA mini is 10 in at 0.3 lb and comes with three blades. The trade-off is reach and stroke length, so a compact saw can feel slower on a thick bolt.

How to hacksaw a bolt or screw

Good technique saves more time than extra effort. Follow these steps:

• Put on safety glasses and light work gloves. Metal chips and broken blade pieces can fly.
• Clamp the bolt in a vise or locking clamp so it cannot twist. Cut as close to the clamp as you can to cut down on vibration.
• If the bolt is stuck in a part, protect the part with a thin piece of wood or cloth in the cutting path.
• Fit the blade with the teeth pointing away from the handle, so it cuts on the push stroke, and tighten it until it is firm.
• Start with a few light backward strokes to make a small groove, or file a notch first.
• Use long, steady forward strokes with light pressure. Lift slightly or ease off on the return.
• Slow down near the end so the cut-off piece does not drop or kick.
• Smooth the cut end with a file, because the edge will be sharp.

How long will it take?

There is no single answer. A small plain steel bolt can take a few minutes with a sharp blade and a firm hold. A thick or stainless bolt can take much longer, and a hardened one may not cut at all.

Three things change the time most: the bolt's diameter, the metal it is made from, and how sharp the blade is. A worn blade slides and polishes the metal instead of cutting it. Blades are consumables, so if the cut slows to a crawl, swap in a new one before you push harder.

Pushing harder rarely helps. Heavy pressure bends the blade and makes it wander. Steady, even strokes at a comfortable pace cut faster than rushed ones.

Cutting a padlock

Only cut a padlock you own, or one you have clear permission to remove. Cutting someone else's lock is not a repair.

If the lock is yours and the key is lost, aim at the shackle, which is the curved loop. The lock body is thick and hard to cut. Brace the lock so it cannot spin, and cut slowly with a fresh bi-metal blade.

Many padlocks are built to resist this. Hardened shackles can be far tougher than the blade, and shrouded designs leave almost no loop exposed to saw. In those cases the blade will skate and wear, and a hacksaw is the wrong tool.

If a hacksaw fails, bolt cutters or an angle grinder are the usual next steps. A grinder throws sparks and hot metal, so it needs eye protection, a face shield, hearing protection and a clear area free of anything flammable. Never grind near fuel, gas or cleaners.

Safety checklist

Hacksaws are simple, but a few habits prevent most injuries.

• Wear safety glasses at all times, and gloves for handling sharp cut ends.
• Keep your free hand out of the line of the blade.
• Do not cut near live wiring or a pipe that may carry gas or pressure. Shut off power and supply first.
• Hold the work firmly. A bolt that spins or drops can cause cuts and crushed fingers.
• Let freshly cut metal cool before you touch it, since friction heats it.
• If you are working up high on a ladder, use a stable stance and consider another tool or a second person.

Frequently asked questions

Why does my hacksaw blade keep breaking on a bolt?

Common causes are a loose blade, too much pressure, a twisting cut, or a bolt that is not held firmly. Retighten the blade, clamp the bolt close to the cut, and use lighter, even strokes.

Should I use cutting oil?

A few drops of cutting oil or lubricant on the cut can reduce heat and help the blade last on tough metal. Wipe up any excess before you handle the work.

Can a hacksaw cut a bolt that is already in a nut?

Yes, if you can reach it. Cut the exposed bolt end or saw through the nut's side, but guard the surrounding surface so the blade does not scratch it.

Is a mini hacksaw enough for small screws?

Often yes. A compact saw with a 24 TPI bi-metal blade handles small screws and thin bolts. For thick or hardened pieces, use a full frame or another tool.