How do I change the strimmer head to a brush cutter blade

Quick Answer

To convert your petrol machine from a grass trimmer head to a brush cutter blade, you must lock the gear head, remove the trimmer head assembly, and install the blade using the correct washers and locking method. The blade nut is typically left-hand threaded (tightened anti-clockwise).

⚠️ Safety Notice

Before starting:

• Switch off the engine and allow it to cool completely.
• Remove the spark plug cap to prevent accidental starting.
• Wear protective gloves and eye protection.
• Ensure the cutting attachment is stationary before handling.

Incorrect installation can result in serious injury or damage to the machine.

Changing from Grass Trimmer to Brush Cutter Blade

Step 1 – Lock the Gear Head

1. Align the slot in the flanged washer with the slot in the gear head.
2. Insert the supplied hex wrench through both slots.
3. This locks the gear head and prevents it rotating during removal.

Step 2 – Remove the Trimmer Head

1. Unscrew the grass trimmer head by turning it clockwise.
2. Remove the cupped washer and flanged washer.
3. Keep these parts safe for future reassembly.

Step 3 – Install the Brush Cutter Blade

1. Fit the flanged washer onto the shaft with the hollow side facing the gear head.
2. Place the brush cutter blade onto the flanged washer.
3. Ensure the raised centre of the washer passes through the blade hole.
4. Confirm the blade sits flat and is correctly aligned.

Step 4 – Fit the Retaining Hardware

1. Install the cupped washer with the raised centre facing away from the blade.
2. Fit the blade retaining nut onto the shaft.

Step 5 – Secure the Blade

1. Reinsert the hex wrench into the locking slots to hold the gear head in place.
2. Tighten the blade nut by turning it anti-clockwise (left-hand thread).
3. Tighten securely using the supplied tool.

⚠️ The blade must be firmly secured before operation.

Changing Back to Grass Trimmer

To convert back:

1. Lock the gear head using the hex wrench.
2. Remove the blade nut, cupped washer, and blade.
3. Refit the flanged washer.
4. Screw the trimmer head onto the shaft by turning it anti-clockwise.
5. Tighten securely before use.

Changing from Brush Cutter to Grass Trimmer

Step 1 – Remove the Blade

1. Hold the flange in place using an Allen key.
2. Unscrew the retaining nut by turning it clockwise.
3. Remove the blade.
4. Remove and retain any shield washers.

Step 2 – Fit the Trimmer Head

1. Continue holding the flange with the Allen key.
2. Screw the trimmer head onto the shaft by turning it anti-clockwise.
3. Tighten fully until secure.
4. Remove the Allen key.

Refitting the Brush Cutter Blade

If reinstalling the blade:

• Remove the trimmer head.
• Refit shield washers in the correct order.
• Position the blade correctly on the shaft.
• Lock the flange with an Allen key.
• Tighten the retaining nut anti-clockwise.

Important Notes

• Always ensure the gear head is locked before loosening or tightening components.
• Blade nuts are usually left-hand threaded (anti-clockwise tighten).
• Incorrect assembly may cause vibration, poor performance, or unsafe operation.

Frequently Asked Questions

Why does the blade nut tighten anti-clockwise?

Because brush cutter blades typically use a left-hand thread to prevent loosening during operation.

Do I need special tools to change the head?

Yes. Most models require a locking hex wrench or Allen key to hold the gear head in place.

Can I use the machine if the blade is slightly loose?

No. A loose blade is extremely dangerous and must be tightened securely before use.

What happens if I install the washers incorrectly?

Incorrect washer placement can cause vibration, blade movement, or damage to the gear head.