How To Change The Spool On A Grass Trimmer

Posted on by Haines Watts

Invented in the 1970s the humble strimmer has many names depending on where you live in the world, but one thing is sure, it's certainly the best tool for the job when it comes to the edges of a lawn. Like most power tools there are many grass strimmer varieties to choose from with a lot of separate care instructions. However one of the most common questions we get from our customers is, ‘How do I change the line on my grass trimmer spool?’

Going back to basics, the tool works on the principle that a line spun at high speed becomes stretched due to high acceleration. The tension in the line makes it stiff and the inertia of the line gives it the energy to cut. With the power generated it's not surprising spool lines need regular replacement.

Of course, every make of strimmer has its own instructions and design so we will give you a guide on the three key types of strimmer and how to simply change the line on each.

Firstly, some top tips…

  • Don’t force anything. If the spool doesn’t slide easily back into the head, for example, don’t try to jam it in as it could easily break. Take a step back, re-read the instructions, and review what you have done to try to troubleshoot what is not working.

  • If you are having difficulty threading the cutting line into the starter hole in the spool, try cutting the tips at an angle.

  • If you have a single - or double-line trimmer, disassembling the head is a good opportunity to clean it out. Wipe it clean with a soft rag.

 Changing the Spool Or Line on a Single-Line Trimmer

  • Firstly prepare your new spool

The length and width of line you need varies based on your strimmer, we won’t second guess this. If you purchase the wrong width of line, the strimmer will not work correctly, so make sure to take the model specifications into account. The length to which the line should be cut also varies, from around 15” to 25”

If you really don’t know then go for a longer length and then cut it to a better size later on.

  •  Remove the retaining cap from the trimmer head.

After making sure your strimmer is off, you need to take off the outer protective cap. Depending on the make of the strimmer, this will probably involve either unscrewing it, pressing one or multiple tabs, or a combination of the two.

Ideally, these should be designed to be relatively intuitive and once removed, you will be able to then access the strimmer spool below. Remove any leftover line before beginning to thread any new material through.

  •  Locate the starter hole in the spool

Remove the strimmer spool from its container and locate the starter hole in the spool.

Insert the tip of the strimmer line, and wind in the direction of the arrows which should be on the spool itself. Wrap the line in neat, straight rows, to make sure you prevent jams from occurring during use. When there is around 6” of line remaining, you should be able to lock it into the retainer slot on the spool to hold it in place.

  •  Line up the spool and the container to thread the line

Now all that is left to do is to replace the spool into the strimmer head. There will be two slots or holes that need to line up so the new strimmer line can feed through without obstruction. Slot the line through and replace the retaining cap to hold it all in place. Make sure any locking mechanisms are re-engaged to prevent anything from coming loose


2) Changing the Spool Or Line on a Double-Line Trimmer 

The initial steps are fairly similar for a double line spool, apart from the fact, as the name suggests, you need two lines instead of one.

  • Locate the starter holes in the spool.

Insert the start of the first length of strimmer line into one starter hole, and wind in the direction of the arrows displayed on the spool. Once again, make sure to wrap in straight lines to avoid any jams, With around 6” left of the line, snap it into the retainer on the spool to hold it in place. Repeat this process with the second line.

  •  Line up the spool and the container to thread the line

With both lines now in place, each line end should be at opposite sides of the spool, to match the eyelets on the outside of the strimmer head. Thread each line through the respective slot in the strimmer head and replace the retainer cap.


3) Changing the Line on a Speed-Feed Trimmer

Speed feed strimmers really are the height of convenience. No fiddly winding to needed as suggested by the name ‘Speed-Feed’. As with the other types of strimmer, you need to cut the required length of line for your model of strimmer.

Once you have your new line, you need to ensure your strimmer is off and then rotate the strimmer cap so the arrows align with the eyelets on either side 

All that is needed then is to feed the line through one eyelet and out the other. Continue to feed it through until both sides become even in length, then you are ready to go!

If you need any guidance when using BP Tools grass strimmers, head over to the grass strimmers page to view the specifications and instruction manuals for each of our models.

30 Day Returns
Secure Encrypted Checkout
Speak to our service team
Free UK Delivery*
You have successfully subscribed!