Work knife: a utility knife you can keep sharp all day
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Quick answer
For cutting drywall, carpet, house wrap, cardboard and plastic sheeting, a utility knife with replaceable snap-off blades suits the job: when the edge dulls, you snap off a segment instead of sharpening. OLFA's L-1 takes 18 mm blades with eight snap-off segments, and its H-1 takes heavier 25 mm blades for roofing and cement board. OSHA's hand tool guide says knives must be kept sharp, because dull tools cause more hazards than sharp ones.
18 mm or 25 mm?
| Feature | OLFA L-1 (18 mm) | OLFA L-5 (18 mm) | OLFA H-1 (25 mm) |
|---|---|---|---|
| Handle | ABS | Fiberglass-reinforced, anti-slip grip | ABS with anti-slip rubber insert |
| Lock | Ratchet lock | Ratchet lock | Ratchet lock |
| Blade loaded | Silver snap blade, 8 segments | Black snap blade (LBB) | Extra heavy-duty silver snap blade |
| Extra | None listed | Metal multi-pick | None listed |
| Uses OLFA lists | Carpet, cardboard, drywall, house wrap, shingles | Carpet, laminates, linoleum, turf, straps | Roofing, cement board, drywall, carpet |
All three have a stainless-steel blade channel and tool-free blade changes, per OLFA. Pick 18 mm for general trade and household cutting, and 25 mm when you cut thick or tough materials such as cement board or shingles.
Choose the blade for the material
- Standard silver snap blades: the general-purpose blade the L-1 and H-1 ship with.
- Black blades: OLFA says its black Ultra-Sharp and Speed blades are 25% sharper than its standard silver blades; the LFB Speed blades add a non-stick coating for foam board, insulation and ceiling tile.
- Hook blades: OLFA makes LH (18 mm) and HH (25 mm) hook snap blades, which the L-1 and H-1 accept.
- Serrated and solid blades: the L-1 also accepts LWB serrated insulation blades and L-SOL solid blades.
- Saw blades: the H-1 accepts OLFA's HSWB saw blade.
Check the blade width before buying refills: 18 mm blades will not fit a 25 mm knife.
Changing a blade safely
OLFA's instructions for its ratchet-wheel knives, including the L-1, L-5 and H-1:
- Turn the ratchet-wheel dial counterclockwise to loosen the lock.
- Slide the ratchet-wheel assembly past the base of the handle to remove it.
- Remove the dial from the blade, then carefully slide the used blade out.
- Dispose of the used blade in a sharps container.
- Insert the new blade, placing its hole over the raised mounting point.
- Slide the assembly forward and turn the dial clockwise to tighten.
Snapped segments are as sharp as a blade, so keep a lidded container for them in your kit.
Safe use on the job
- Keep it sharp: OSHA's Hand and Power Tools booklet says knives and scissors must be sharp, since dull tools can cause more hazards than sharp ones; snap or change the blade when cuts start to drag.
- Watch your direction: OSHA says to direct knives away from aisle areas and away from other employees working close by.
- Expose only what you need: the ratchet lock lets you set blade length; extend only what the cut needs.
- Employers: OSHA says employers shall not issue or permit the use of unsafe hand tools, and workers should be trained in their use.
A work knife in a home or emergency kit
After a storm, a utility knife cuts tarps, plastic sheeting, rope and tape for temporary repairs, and opens supply cases. Store it with a pack of spare blades and keep it with your other tools. For a knife you carry every day, see our pocket knife and EDC knife guides; for outdoor tasks, see our fixed blade knife guide.
What to look for when you buy
All-around 18 mm: OLFA L-1 Ratchet-Lock Utility Knife
Best for: General trade, household and storm-repair cutting
OLFA lists an ABS handle, ratchet lock, stainless-steel blade channel, tool-free blade changes, an 18 mm silver blade with eight snap-off segments and compatibility with all OLFA 18 mm blades.
Watch out: No grip insert; the L-5 adds a fiberglass-reinforced, anti-slip handle.
See options on Amazon (opens Amazon in a new tab)Heavy 25 mm: OLFA H-1 Extra Heavy-Duty Utility Knife
Best for: Roofing, cement board and thick materials
OLFA lists an ABS handle with an anti-slip rubber insert, ratchet lock, stainless-steel channel and a 25 mm extra heavy-duty snap blade, and accepts hook and saw blades.
Watch out: Takes only 25 mm blades; larger in the hand than an 18 mm knife.
See options on Amazon (opens Amazon in a new tab)Refills: OLFA LFB-10B 18 mm Black Speed Blades
Best for: Foam board, insulation and ceiling tile
OLFA lists Japanese carbon tool steel, a non-stick coating, eight segments per blade, a fit for most 18 mm snap knives and a storage case of 10.
Watch out: Carbon steel; store dry in the case.
See options on Amazon (opens Amazon in a new tab)Questions people ask
- What is the best kind of knife for work?
- For most trade cutting, a utility knife with replaceable snap-off blades, so you always work with a sharp edge.
- What is the difference between 18 mm and 25 mm utility knives?
- Blade width; OLFA lists its 25 mm H-1 for tougher materials like roofing and cement board.
- How do you change an OLFA utility knife blade?
- Loosen the ratchet dial, slide out the assembly, swap the blade over the mounting point and tighten the dial.
- Why keep a work knife sharp?
- OSHA says dull tools can cause more hazards than sharp ones.
Sources
- 18mm Ratchet Lock Utility Knife L-1, OLFA
- 25mm Classic Extra Heavy-Duty Utility Knife H-1, OLFA
- 18mm Fiberglass Utility Knife L-5, OLFA
- 18mm LFB-10B Ultra-Sharp Black Speed Blade, OLFA
- Hand and Power Tools (OSHA 3080), Occupational Safety and Health Administration