How to Replace the Line on a Black and Decker Trimmer

Co-authored by wikiHow Staff

Last Updated: October 21, 2021

Black and Decker trimmers are useful gardening tools that can help you eradicate weeds and trim your shrubs. Over time, however, your line may become worn out or broken, making your trimmer useless. Luckily you can easily replace the string and spool for your trimmer if you follow the correct procedures. While these steps will help you replace the line on most Black and Decker trimmers, your model may be old or have a different feeding method for your line. The safest way to see if your model differs is by reading the instruction manual or visiting Black and Decker's support page.

Part 1

Part 1 of 3:

Removing the Old Line and Spool

1
Turn off all power to your trimmer. To safely replace the line on your power trimmer, it's important that it doesn't turn on while you work on it. Unplug the trimmer or remove the ion battery that came with it. This will ensure that you won't accidentally turn on the trimmer and injure yourself.^{[1]
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2
Sit the trimmer on a table or chair. To more easily work with your Black and Decker trimmer, set it on top of a table or a chair so that you don't have to bend over constantly to work with it. Choose a table or desk that comes up to your waist so you can easily replace the parts.

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3
Remove the cap on the trimmer head. There will be a cap that covers your line on your Black and Decker trimmer. To remove this, use your fingers to press in the tabs that are on both sides of the cap. Once the tabs are pressed, simply lift up on the trimmer cap to remove it and expose the spool underneath.
4
Pull the spool from the cap. Turn over your cap to reveal the line and spool. There will be two indentations or eyelets on the side of your cap that helps hold the line in place. Pull your line free from the holes on the cap, then grab onto the spool and carefully wiggle it free from the cap.^{[2]
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5
Remove the old line from the spool. To remove the old line, lift it from the eyelets that hold it in place and pull the free end of the line. This will result in removing the old string. Repeat the process on the other side of the spool to remove all of the old lines.^{[3]
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- Wear gloves when working with your trimmer.

Part 2

Part 2 of 3:

Replacing the Old Line

1
Thread your new line into the holes designated on your spool. Purchase a .080 inch (2.0 mm) diameter round monofilament line from a hardware store. Do not use a serrated or heavier line because it can overload the motor and cause overheating.
- You can also buy pre-threaded spools from Black and Decker's website or at some hardware stores.
2
Wind the line around the spool, following the arrows on the spool. Feed the line through the hole and begin to wrap it around the spool. The more you overlap your spool, the more likely it is to get tangled when you start working with it. Instead, wrap the spool so that the line is wrapped next to itself, not over itself.
- Most Black and Decker models will have you wrap the string counter-clockwise.
3
Secure the line to the spool and cut the line. Allow for 6 inches (15.24 cm) of slack on the end of your line after you're done wrapping it around the spool. Cut the thread with gardening shears or sharp scissors and put the excess line through the eyelets on the spool to hold them in place.^{[4]
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4
Thread and wind the other side of the spool. Repeat the steps to wind up and secure the other line on your spool. Again, follow the arrows when you are winding up the line.

Part 3

Part 3 of 3:

Installing the Spool

1
Set the spool into the cap. Make sure that the eyelets on the cap and the spool are also lined up. Line up the hole in the center of the spool with the center of the cap and gently press the spool back into the cap. Once you hear a click, turn the cap over and shake it to make sure that the spool is secure.
2
Lace the line through the eyelets on the cap. Pull the excess line out of the eyelets on the spool and push them into the eyelets on the cap. Your spool is now ready to go back into your trimmer.
3
Line up the tabs on the cap and trimmer head and press down. Press down on the side tabs on your cap to fit it into the trimmer head. Lightly press on the cap until you hear a click. Your spool is now replaced.

Community Q&A

Question

How does the string feed itself - banging the reel on the ground worked with a previous trimmer, but not with this small Black & Decker one. What can I do?

Community Answer

Check if it's an automatic feeder or a bump feeder. Your old trimmer was a bump feeder, so you did the right thing when trying to feed the string, however doing this on an automatic feeder can damage your model. Read the box and instructions. If it's an automatic feed you don't need to do anything--it will adjust on its own. If you've already banged it and it doesn't work, it's possible you've damaged the feed motor.
Question

I have a B&D 20 V battery combo lawn and edger. When should I get a new string?

Community Answer

If you don't already have a spare line, buy one now. That way you have it when it is needed. You replace it when there is no more of the old line left.
Question

When winding the spool should the line be wound in the same direction the spool turns during operation?

Community Answer

Follow the arrows on the side of the spool for the best results when winding the spool. Typically this is counter-clockwise.