Few things are more frustrating than a whipper snipper that won't feed line properly or runs out of line mid-job. The good news is that replacing trimmer line is a straightforward task once you understand the process. Whether you're dealing with a basic bump-feed spool or a more complex twin-line system, this guide will walk you through replacing your line correctly.
Improperly wound line is the most common cause of feeding problems and premature line breakage. Taking a few extra minutes to wind the line correctly saves frustration later and ensures your trimmer performs at its best.
Always use the correct diameter line for your trimmer (check your manual) and wind it in the direction indicated by the arrows on the spool. These two simple rules prevent most line-related problems.
Understanding Your Spool Type
Before you start, identify which type of spool your whipper snipper uses:
Single-Line Spools
Common on smaller, budget trimmers. One length of line exits from one side of the spool. Simpler to wind but may have less cutting efficiency than dual-line systems.
Dual-Line Spools
The most common design. Two lengths of line exit from opposite sides of the spool. Provides more balanced cutting and is more efficient for most tasks.
Pre-Wound Spools
Some manufacturers sell pre-wound replacement spools. These are convenient but more expensive than bulk line. Good option if you find winding frustrating.
What You'll Need
- Replacement trimmer line (correct diameter—usually 1.6mm to 2.4mm)
- Safety glasses
- Clean workspace
- Scissors or cutting tool
- Your trimmer's manual (helpful but not essential)
Always disconnect the power source before working on your whipper snipper. For battery models, remove the battery. For petrol models, ensure the engine is off and has cooled. For electric models, unplug from the power outlet.
Step-by-Step: Replacing Line on a Dual-Line Spool
Step 1: Remove the Spool
- Turn the trimmer head so you can access the spool cover
- Press the tabs on the spool cover and pull it off (some models twist off counter-clockwise)
- Remove the spool from the hub, noting how it sits and which direction it faces
- Remove any remaining old line from the spool
Step 2: Prepare Your New Line
Cut a length of new trimmer line. For most home trimmers, 3-4 metres is appropriate. Check your manual for the recommended length—some spools have a maximum capacity.
Soak your trimmer line in water for 24 hours before winding. This softens the line, making it more pliable to wind and less likely to become brittle. It also helps the line feed more smoothly when in use.
Step 3: Wind the Line
For dual-line spools with a centre hole:
- Find the centre of your line length and fold it in half
- Insert the loop into the anchor slot or hole in the centre of the spool
- Wind each half of the line in the direction indicated by the arrows on the spool (usually counter-clockwise when viewed from above)
- Wind in neat, tight rows—avoid overlapping or crossing the line
- Leave approximately 15cm of line unwound on each side
- Secure the loose ends in the holding slots on the spool edge
For spools with separate starting points for each line:
- Cut two equal lengths of line (usually 1.5-2 metres each)
- Insert one end of each line into its respective anchor hole
- Wind each line separately in the direction of the arrows
- Keep the lines in their separate channels if the spool has dividers
- Secure loose ends in holding slots
Step 4: Reassemble the Cutting Head
- Thread the loose line ends through the exit holes in the spool housing
- Place the spool back into the hub, ensuring it sits correctly
- Replace the cover, pressing or twisting until it clicks securely
- Pull each line end firmly to release them from the holding slots
- Trim the lines to match the length indicated by the cutting blade on your guard
Choosing the Right Trimmer Line
Diameter
Use the diameter specified in your trimmer's manual. Using line that's too thick can strain the motor and cause overheating. Line that's too thin wears quickly and lacks cutting power.
- 1.6mm: Light-duty trimmers, basic grass
- 2.0mm: Mid-range trimmers, standard lawns
- 2.4mm: Heavy-duty trimmers, thick grass and weeds
- 2.7mm+: Professional and petrol units
Line Shape
Trimmer line comes in various cross-sectional shapes:
- Round: Most common, good all-rounder, least aggressive
- Square: More aggressive cut, good for thicker grass
- Star/Multi-sided: Most aggressive, cuts tough weeds efficiently
- Twisted: Reduced noise, good cutting, often premium priced
Troubleshooting Common Problems
Line Won't Feed
- Line may be wound too tightly or overlapping
- Line may be fused together from heat—rewind with fresh line
- Exit holes may be clogged with debris—clean thoroughly
- Bump knob may be worn—check for damage
Line Feeds Too Much
- Spring inside spool housing may be weak or missing
- Line may be wound too loosely
- Spool may not be seated correctly
Line Breaks Constantly
- Line may be old and brittle—use fresh line
- Cutting head may be striking objects frequently—adjust technique
- Line diameter may be too thin for the vegetation
- Line may be low quality—try a reputable brand
With proper line installation, your whipper snipper will feed smoothly and cut efficiently. Take your time with the winding process—a few extra minutes upfront saves significant frustration in the field.