Threading a grass trimmer means removing the spool from the cutting head, winding fresh trimmer line onto the spool in the direction shown by the arrows, and feeding the loose ends through the eyelets on the head before reassembling it. The exact steps differ slightly depending on whether you have a bump feed head, which releases more line when you tap the head on the ground, or a fixed line head, which you stop to adjust by hand. The core process is the same for both: match the line size to your head, wind it evenly and snugly, thread the ends through the eyelets, and secure everything before restarting the trimmer.
Before You Start: Safety and Preparation
Before touching the cutting head, always disconnect the power source. On a gas trimmer, remove the spark plug wire. On an electric trimmer, unplug it. On a battery trimmer, remove the battery. This prevents accidental startup while your hands are near the blade or line.
Gather what you need: a new length of trimmer line in the correct diameter, scissors or line cutters, and a clean flat work surface. Wear eye protection throughout the process. Never reach into the head while the trimmer is connected to power.
Identify Your Trimmer Head Type and Line Size
Most grass trimmers use one of two head types:
- Bump feed heads hold line on a removable spool. You tap the head on the ground during use to release more line.
- Fixed line heads hold a set length of line threaded through channels. You stop the trimmer and pull more line by hand when needed.
To find the correct line diameter, check the spool, the head itself, or the owner’s manual. The diameter is usually printed on these parts. Using line that is too thick can strain the motor or engine and damage the head. Using line that is too thin may cause poor cutting performance and frequent breakage.
How to Thread a Bump Feed Trimmer Head
Bump feed heads are the most common type. Follow these general steps:
1. Remove the Spool
Press the release tabs or turn the knob on the head to unlock the spool. Lift the spool out of the head. Remove any old line from the spool.
2. Cut New Line
Cut a length of line appropriate for your spool. Check the manual for the recommended length, as it varies by head size. As a general rule, most residential trimmers use between 10 and 25 feet of line per spool.
3. Anchor the Line
Find the anchor hole or notch on the spool. Insert one end of the line into the anchor hole to secure it.
4. Wind the Line
Wind the line onto the spool in the direction shown by the arrows on the spool. Wind evenly, keeping each wrap next to the previous one without crossing over itself. Wind until only a short tail remains on each side.
5. Thread Through Eyelets
Place the spool back into the head. Feed each loose end of the line through the corresponding eyelet on the head. The eyelets are the small openings where the line exits the head.
6. Reassemble
Press the spool firmly into the head until it clicks or locks into place. Pull gently on the line ends to ensure they move freely through the eyelets.
How to Thread a Fixed Line Trimmer Head
Fixed line heads are simpler but require a different approach:
1. Remove Old Line
Pull out any remaining line from the head. Some heads have a release button or slot to free the line.
2. Cut New Line
Cut a length of line appropriate for your head. Fixed line heads typically use shorter lengths than bump feed spools.
3. Insert the Line
Feed the line through the opening in the head until it emerges on the other side. Pull the line through until equal lengths extend from both sides of the head.
4. Secure the Line
Some fixed line heads have a locking mechanism or notch to hold the line in place. Ensure the line is seated properly before use.
Winding and Securing the Line Correctly
Proper winding prevents jams and tangles. Wind the line hand-tight, not so tight that it stretches, but snug enough that it does not unravel. Keep the wraps side by side without overlapping. Before reassembling the head, make sure the loose ends pass cleanly through the eyelets. If the line is not seated in the eyelets, it will not feed correctly.
Common Mistakes to Avoid
- Winding in the wrong direction: This is the most common cause of line not feeding. Always follow the arrows on the spool.
- Overfilling the spool: Too much line can cause jams and make it difficult to reassemble the head.
- Using the wrong diameter: Check the manual or the head itself for the correct size.
- Leaving too little line exposed: If the line ends are too short, they may not feed properly.
- Failing to seat the line in the eyelets: The line must pass through the eyelets before you reassemble the head.
Troubleshooting: Line Won’t Feed or Keeps Breaking
If the line will not feed, check the winding direction and ensure the line is not crossed on the spool. If the line breaks frequently, inspect the eyelets for sharp edges that may be cutting the line. Debris packed in the head can also interfere with feeding. Clean the head regularly to remove grass and dirt buildup.
If problems persist, consult the owner’s manual or a qualified dealer. The spool or head may be worn and need replacement.
Keeping the Trimmer Head in Good Working Order
After each use, remove grass debris from the head. Check the eyelets for wear or cracks. Store spare trimmer line in a dry place, away from direct sunlight, which can make the line brittle over time.
