How to wind strimmer line on a standard bump spool
Updated: October 2026
The bump head is empty, the bulk reel is on the bench, and the last attempt either jammed, failed to feed, or snapped at the eyelet. How to wind strimmer line, on a head that takes a spool you load yourself, comes down to direction, fill and length. This is the procedure, not a ranking of the twelve listings on the [trimmer line comparison](/hub/lawn-and-garden-equipment/trimmer-line). If the cord will not enter the eyelet at all, the diameter is wrong and the next page is [which size you need](/hub/lawn-and-garden-equipment/trimmer-line/sub/trimmer-line-which-diameter). Our links can earn a commission.
The bump head is empty, the bulk reel is on the bench, and the last attempt either jammed, failed to feed, or snapped at the eyelet.
The bump head is empty, the bulk reel is on the bench, and the last attempt either jammed, failed to feed, or snapped at the eyelet. How to wind strimmer line, on a head that takes a spool you load yourself, comes down to direction, fill and length. This is the procedure, not a ranking of the twelve listings on the trimmer line comparison. If the cord will not enter the eyelet at all, the diameter is wrong and the next page is which size you need. Our links can earn a commission.
Our top picks
| Badge | Product | Stated diameter | Shape | How it loads | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Dapetz Dapetz 1.5 mm x 20 m | 1.5 mm | Round | Wind onto the existing spool | 8.6 | about £2.99 | View offer |
 Oregon Oregon 2.4 mm x 15 m round | 2.4 mm | Round | Wind from the donut | 9.0 | about £5.99 | View offer | |
| Alternative |  Zeqeey Zeqeey 1.6 mm x 100 m | 1.6 mm (bullet also 1.65 mm) | Round | Wind onto the machine spool | 7.6 | about £10.99 | View offer |
On this page
Open the right kind of head
Before you open anything, take the battery out, unplug the mains lead, or switch a petrol engine off. Then identify the head, because three patterns are not the same job. A standard bump spool comes apart: you wind it, thread the eyelets, and close the cap. Husqvarna UK’s reload article names winding the wrong way as the usual mistake.
A Comfort head takes line through the eyelets from the outside, and you twist the base. You do not open it for a normal refill. The KINGTAIXIN Flymo spool and the Yeaskyart cassettes snap in, so the steps below do not apply to them. If your head is the open-spool type, find the arrow before you cut a length off the reel.
Follow the arrow and stop before the rim
Yourspares’ winding guide is the sequence once the spool is out. Seat about 10 to 15 cm in the anchor if the spool has one, then wind with the arrow under light tension, in flat layers, without crossing. Leave about 10 to 15 cm free, thread the eyelets, seat the spring if there is one, and close the cap. Stop at the fill line or under the rim.
Line wound against the arrow will not feed when you bump, and line piled over the rim jams the cap. If the bump does nothing, undo a crossed layer and wind once more, evenly. If the nylon will not pass the eyelet, it is the wrong diameter or shape. Do not file 2.4 mm down to fit a 1.6 mm head.
Soak only as the maker suggests
Stiff nylon is a real reason a fresh wind springs off the spool, and soaking is not one universal step. STIHL UK’s round 2.0 mm line page suggests 12 to 24 hours in water. Yourspares’ winding page does not set a soak. Zeqeey’s bullet says 24 hours, which is that listing’s instruction, not a rule for the Oregon donut or the Dapetz coil.
If your maker is silent, wind it dry, and soak only if the line will not lie in flat layers. A soak does not change the diameter.
Leave a short end and keep the guard on
Once the head is back on the shaft, the deflector and its line-limiting blade set the working length. STIHL’s GB safety manual says over-long nylon drops engine speed, the clutch slips, and parts overheat. The Health and Safety Executive’s INDG480 ties the wrong length to an unbalanced head and higher vibration. Start the machine only with the guard on, and let the cutter trim the ends. If a petrol clutch slips at idle on the correct diameter and length, stop and take it to a repairer. Nylon only: that STIHL manual bars wire and metal-reinforced line in a nylon head. DRERIO and Eyoloty are 37 cm by 3.5 mm strands for an AFS 23-37 pattern head. They are inserted, not wound. If that is your machine, this procedure is the wrong one.
Common questions
Which way do I wind the spool?
Wind with the arrow moulded on the spool, in flat layers, under light tension. A wind against the arrow is the usual reason a bump head will not feed. If there is no arrow, use the diagram in that head’s manual rather than copying a neighbour’s machine. Undo a backwards wind before you add more line.
How much line should I put on?
Fill to the line or stay under the rim, and leave a tail of about 10 to 15 cm to thread the eyelet, which is the Yourspares sequence. Heads differ, so a fixed length per side is not a rule. Overfilling jams the cap. Underfilling still works, and you can add line later if the spool has room.
Should I soak the line before I wind it?
Only if the maker of the line or the head says so. STIHL UK suggests 12 to 24 hours in water for its own nylon, and up to a day or two if a dry coil needs softening. Yourspares does not set a soak on its winding page.
How long should the ends be once the guard is on?
Short enough for the guard’s cutter to trim them in the normal way. STIHL’s GB manual links over-long line to clutch slip and overheating on a petrol machine, and HSE guidance links the wrong length to vibration. Do not run the strimmer with the guard removed to get a longer cut.
Can I wind 3.5 mm pre-cut strands into a bump head?
No. The 37 cm by 3.5 mm strands for an AFS 23-37 pattern head are inserted in that head. They are not a refill for a domestic bump spool. A cassette is already wound: you snap the shell in.
When should I stop and take the head to a repairer?
Stop when a correct rewind still will not feed and the eyelet is the right size, when the guard or the head is cracked, or when a petrol clutch slips at idle on the right line at the right length. A second, tighter wind will not repair a broken spool carrier.
Related pages
Sources
Sources checked for this comparison; last retrieved on 17 October 2026.
- HSE, chain-flail bulletin for brush cutters (retrieved 17 October 2026)
- HSE INDG480, hand-arm vibration (retrieved 17 October 2026)
- GOV.UK, outdoor noise regulations 2001 (retrieved 17 October 2026)
- ISO 11806-1:2022, brushcutters and grass trimmers (retrieved 17 October 2026)
- STIHL GB safety manual for FS machines (retrieved 17 October 2026)
- STIHL UK, AutoCut 2-2 mowing head (retrieved 17 October 2026)
- Yourspares, how to choose strimmer line (retrieved 17 October 2026)
- Consumer Rights Act 2015, section 22 (retrieved 17 October 2026)
- Bosch DIY, extra-strong line 37 cm x 3.5 mm (retrieved 17 October 2026)