How to Change Weed Eater String Step by Step Fast
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To learn how to change weed eater string, first find out how your trimmer feeds line, because that decides the whole job. Most string trimmers use a bump-feed spool that you wind by hand and release with a tap on the ground, an auto-feed head that cuts extra line to length as it runs, or a fixed-line head that takes pre-cut line pieces placed into slots. Identify the head type, unplug or remove the battery before you touch the cutting head, wear eye protection, and then follow the feed method your model uses.
Quick answer
- Check the feed type first: bump-feed, auto-feed, or fixed-line.
- Disconnect power or remove the battery before you open the head.
- Wear safety glasses or a visor, since trimmer line can throw debris at speed.
- Use the line diameter and head instructions from your own model manual.
Know which feed style your trimmer uses
The feed style is the single most important thing to identify before you start. According to the general reference on string trimmers, a bump-feed trimmer has line that is hand-wound onto a reel before use. When the line wears down or breaks off, the operator taps the reel on the ground, which releases more line from the spool. That design is the classic one, and it is the one most people picture when they think of a weed eater.
An auto-feed system is a variation on the bump-feed idea. Some newer bump-feed models include a small cutter that keeps the exposed line at a length that can be swung effectively. You still tap the head to advance line, but the built-in cutter trims the line to a usable length, so you do not have to stop and trim it by hand each time.
A fixed-line head works differently. Instead of a wound spool, it takes pre-cut line inserts that you place into slots in the head. The same reference notes that this makes feeding and troubleshooting easier than with bump-feed systems. If your trimmer has slots on the head and no spool to unwind, you are looking at a fixed-line design and should use pre-cut inserts.
Safety before you start
Safety comes first, because the cutting head is the part most likely to cause an injury during a line change. Disconnect the power source. On a corded model, unplug it. On a battery model, remove the battery pack. Do this before you open the head, turn the trimmer over, or reach near the cutting head with your hands.
Wear eye protection. The same general reference says users typically wear safety glasses or a visor, because the trimmer can throw debris at high speed. Bystanders also need to stay clear. Debris can hit people nearby and can damage cars and windows. Work with the trimmer at a safe distance from anyone else in the yard.
Keep the safety shield on the user’s side of the cutting head in place. Do not run the trimmer with the guard removed. If the cutting head is cracked or the shield is missing, replace those parts before you go back to work.
General steps for a bump-feed head
For a bump-feed head, the usual sequence is to open the spool cover, remove the old spool, and clear any leftover line from the spool and the housing. Wind new line onto the spool in the direction marked on the spool or cover, leave the tail ends where your model’s instructions say, and seat the spool back into the head. Close the cover and check that the line exits through the eyelets.
Once the head is closed, reconnect power or the battery and test the feed by tapping the head on the ground while the trimmer is idle. If the line does not advance, check that the spool is seated and the line is wound evenly. Model-specific steps vary, so the owner manual for your trimmer is the final authority on tabs, arrows, and spool layout.
General steps for a fixed-line head
A fixed-line head needs no winding. Remove the cap, take out any worn line pieces, and insert new pre-cut line inserts into the slots as the head design directs. Make sure each insert is fully seated before you replace the cap. Because the line is pre-cut, you avoid the tangles and uneven winding that can happen with a hand-wound spool.
After reassembly, keep the trimmer’s guard in place and check that the cap is secure. Test the trimmer briefly at low speed, with the trimmer pointed away from people, to confirm the line is held firmly and does not come loose.
Products in our listing data
The listing data below covers electric and battery string trimmers. The facts come only from the product listings. Where a feature is not stated in the listing, we say so.
| Listing | Power and head | Stated feature |
|---|---|---|
| BLACK+DECKER 14-inch 2-in-1 trimmer and edger (BESTA510) | Corded electric, 14 inches cut width | Automatic feed spool, 6.5-amp motor, wheeled edge guide |
| DCA 20V 14-inch 3-in-1 cordless trimmer | Battery powered, 14 inches cut width, 4000mAh battery | Bump auto feed head, two speeds (4600 and 6200 RPM) |
| Windpost 5-in-1 cordless trimmer | Battery powered, 5.9 inches cut width | Bump auto feed head, adjustable telescopic rod |
| MtiolHig cordless trimmer for Makita 18V (tool only) | Battery powered, 12 inches cut width | Battery and charger not included, fuel gauge display |
| Bosch GRT18V-40N cordless trimmer (bare tool) | Battery powered, 16 inches cut width | Pro-Tap spool with EasyWind, anti-tangle system |
Each of these uses a head design that the listing describes in its own words. Check your model’s head before you buy replacement line, since the spool or insert type decides what you need. The listing for the DCA trimmer, for example, says the head releases line with a tap, while the Bosch listing describes a Pro-Tap spool with EasyWind and says it adjusts the line automatically as needed.
Choosing the right line for your trimmer
Line size and type should match your trimmer’s head. Using a line diameter that the head was not designed for can cause feeding problems, vibration, or a head that will not hold the line. Check the owner manual or the head label for the approved line diameter. If you cannot find it, the listing for your exact model is the next place to look.
Keep spare line on hand and store it dry and out of direct sun. Old line can become brittle and break inside the head. If line keeps breaking near the head, the usual causes are a line that is too thin for the work, a spool wound unevenly, or a head that is not fully closed.
Common mistakes to avoid
- Changing line while the battery or plug is connected.
- Winding the spool in the wrong direction, so the line does not feed.
- Using line that is much thinner than the head is rated for.
- Running the trimmer with the guard removed.
- Forgetting to check that the cap or cover is fully seated before you test.
Quick routine for a fast change
Set aside a few minutes at the start of the season and check the head once. Clean out grass that has wrapped around the shaft, look for cracks, and confirm the guard is tight. When you change line, do it on a flat surface with the trimmer switched off and the battery or plug removed. That routine keeps the job short and reduces the chance of a rushed mistake.
FAQ
How do I know if my trimmer is bump-feed or fixed-line?
Look at the cutting head. A bump-feed head has a spool with a cover that you open and remove, and you tap the head on the ground to release line. A fixed-line head has slots or a cap where you insert pre-cut line pieces. If your head has no spool at all, it is a fixed-line design.
Do I need to remove the battery to change string?
Yes, that is the safe habit. Remove the battery pack, or unplug a corded trimmer, before you open the head or handle the cutting parts. This prevents the trimmer from starting while your hands are near the head.
Why does my trimmer not feed line when I tap it?
The most common reasons are a spool that is not seated correctly, line wound unevenly, or a head cover that is not fully closed. Check the spool, rewind it in the marked direction, and test again with the trimmer idle and pointed away from people.
Does every trimmer use the same line?
No. Line diameter, length, and head type differ between models. Check the owner manual or the head label for the approved line size before you buy.
Should I wear eye protection while changing line?
Yes. Eye protection is a good habit during the whole job. Any time you test or run the trimmer, wear safety glasses or a visor, because debris can be thrown at high speed.
Bottom line
Changing weed eater string is a short job if you start with the right steps. Identify the feed type, remove power, wear eye protection, and follow your model’s head instructions. If you are unsure which spool or insert your trimmer takes, use the owner manual first. Use the listing details above to compare models, and keep the guard in place every time.
Sources
String trimmer, general reference (line feeding types and safety notes)
Related reading: Top 10 Battery Powered Weed Eaters: 6 Real Picks Compared and How to Cut Tall Weeds With a String Trimmer.
