The steps for replacing line in a single line trimmer head are virtually the same for many trimmer head types, like double line trimmer heads.
1. Remove the Trimmer Head Spool
Removing the spool is the first step in replacing trimmer line in any conventional trimmer head, but trimmer head spools can disassemble in different ways.
The trimmer head pictured above and below disassembles by simply unscrewing the knob around its arbor bolt. Other trimmer heads can use press tab and other twisting styles for disassembly.
2. Insert Trimmer Line and Wind the Line
Single line trimmer heads have just one channel in their spools for winding line. The channel will have a hole in it somewhere that keeps the line in place as it is wound around the spool. Insert one end of the trimmer line in the hole.
Depending on the trimmer head, it might be helpful to bend a small portion of the cutting line at an angle before inserting it in the starter hole. Also, cutting the line at an angle can help this first step on some trimmer heads.
Of course, it is also important to make sure that the replacement line matches the diameter specification of the trimmer head before beginning. Once the line is started correctly in the channel hole, you're ready to wind. Most trimmer heads will indicated the correct winding direction right on the spool somewhere.
It's also important to wind the line carefully, keeping it in neat rows as much as possible. The line will have a much higher chance to feed incorrectly during trimmer use if it suffers from sloppy winding.
3. Snap the Line into its Retaining Notch
A conventional trimmer head will have a retainer on its spool. Snap the end of the trimmer line into the retainer after it is wound around the spool. The retainer will hold the line in place as the spool is replaced in the trimmer head assembly.
4. Replace the Trimmer Head Spool
With the cutting line held in place, the spool is ready to be replaced in the trimmer head assembly.
First feed the extra trimmer line through the trimmer head eyelet. Make sure to release the line from the retainer before completely securing the spool into position.
Replace any knobs, bolts, or other trimmer head pieces removed during disassembly.
Your single line trimmer line is now reloaded, and your trimmer should be ready to get back to work.
Although there are many steps to reloading line the conventional way, a little practice and familiarity with your trimmer will speed the process up a great deal. Once you're up to speed, reloading trimmer line this way can take less than five minutes.
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