Black and Decker LST400 LST420 LST522 LST1018 Trimmer Spool Retaining Cap PETG

Black & Decker 20V String Trimmer Line Spool Retaining Cap

Replacement spool retaining cap for Black & Decker 20V cordless string trimmers — LST400, and the LST420/LST522/LST1018 family

• This replaces the spool retaining cap only — it does not include a spool or spring. Keep and reuse your existing spool and spring; this just fixes the cap whose tabs snapped off.


• Ships as two loose printed pieces: the cap and a separate tab strap. No glue or hardware needed — press the strap's tabs into the cap by hand to snap them together.


• Printed in PLA. This listing was designed and tested on the LST400; LST420/LST522/LST1018 share the same spool-and-cap system but we have not tested those units ourselves, so verify fit against your original part before ordering.

Part Details

• Material: PLA — the original designer print-tested this part in PLA and reports it holding up fine in use


• Quantity: 1 cap + 1 tab strap (2 printed pieces, snaps together)


• Fit: Line spool retaining cap for Black & Decker 20V string trimmers — replaces the cap only, not the spool or spring


• Brand: Unbranded aftermarket replacement

Why This Cap Breaks

The retaining tabs that hold the cap onto the spool housing are thin by design, and repeated line-feed bumping plus outdoor sun exposure makes that plastic brittle until a tab snaps clean off. Once a tab is gone the cap can't stay seated, so the whole line spool works loose during use. Black & Decker doesn't sell this cap on its own — it only comes bundled with a full replacement spool and spring — so a single broken tab otherwise means buying parts you don't actually need.

Compatible Models

Fits: Black & Decker 20V cordless string trimmer, model LST400 — the exact model this part was designed and print-tested on.

Likely fits: LST420, LST522, LST1018 — these share the same spool-and-cap system, but we have not personally tested fitment on those models. Please verify fit against your original part before ordering, or message us with your model number if you're not sure.

Black & Decker and related marks are registered trademarks of Stanley Black & Decker, Inc. PartsFindr is not affiliated with, endorsed by, or sponsored by Stanley Black & Decker, Inc. Original 3D model design by I-Made-Something on Thingiverse, licensed under Creative Commons Attribution (CC-BY).