Diagonal cutters are hand tools designed to cut wire, leads, zip ties, and small fasteners using two hardened beveled jaws that meet at an angle. They matter in electronics, robotics, electrical work, and general repair because they make clean cuts in tight spaces where scissors or pliers cannot reach. The diagonal head shape lets the cutting edges approach a surface closely, which is useful for trimming component leads near a circuit board.
Understanding the tool helps students choose the right cutter, avoid damaging parts, and work safely.
Key Facts
- Cutting force increases with lever advantage: mechanical advantage = handle distance from pivot / jaw distance from pivot.
- For an ideal lever, F_out = F_in x (d_in / d_out), where d_in is the handle distance and d_out is the jaw distance.
- Diagonal cutters use wedge-shaped beveled edges to concentrate force into a small area and shear the material.
- Hardness matters: cutters must be harder than the wire being cut, or the cutting edges can dent, chip, or become dull.
- Flush cutters make a flatter cut, while standard diagonal cutters leave a small pointed end called a pinch or bevel.
- Safety rule: always direct the cut end away from eyes and wear eye protection because short wire pieces can fly off.
Vocabulary
- Diagonal cutters
- A plier-like cutting tool with angled jaws used to shear wire and small soft materials.
- Cutting edge
- The sharpened beveled part of the jaw that contacts and cuts the workpiece.
- Pivot rivet
- The metal pin or fastener that joins the two handles and allows the jaws to rotate.
- Mechanical advantage
- The factor by which a tool multiplies input force by using lever distances.
- Insulated handle
- A handle covered with nonconductive material to improve grip and reduce electrical shock risk when properly rated.
Common Mistakes to Avoid
- Cutting hardened steel wire with ordinary diagonal cutters is wrong because the wire may be harder than the jaws and can chip or dent the cutting edges.
- Twisting the cutters while cutting is wrong because diagonal cutters are designed for shearing, not prying, and twisting can misalign the pivot or damage the bevels.
- Assuming insulated-looking grips are safe for live circuits is wrong because only tools with a proper voltage rating are designed and tested for electrical protection.
- Placing fingers or eyes in line with the cut is wrong because short wire ends can spring away quickly when the final shear occurs.
Practice Questions
- 1 A student applies 80 N of force at the handles 12 cm from the pivot. The wire is 2 cm from the pivot at the cutting edge. Assuming an ideal lever, what output force acts at the jaws?
- 2 A cutter has a handle distance of 15 cm from the pivot and a jaw distance of 3 cm from the pivot. If the wire needs 600 N of cutting force, what minimum input force is required, ignoring friction?
- 3 Two tools are available for trimming electronic component leads on a circuit board: standard diagonal cutters and flush cutters. Explain which tool is better for making the cut close to the board and why.