Video
Tools & Materials
Glitch in your grinder switch? It's time to face the fix. Whether you are a master mechanic or a garage-based grinder, eReplacementParts.com provides the parts, procedures and facts you need to fearlessly fix what fails you.
The switch button is the part you use to turn the grinder on and off. It attaches to an internal actuating lever that runs all the way to the back of the grinder to the (electrical) switch. With heavy use, it's not uncommon for the switch button to break off the grinder (especially the hooked portion on the bottom of the button).
Impacts (such as dropping the grinder) can also break the switch button. This article provides step-by-step instructions for removing and installing the switch button on a Makita grinder.
Let's get started.
REMOVING THE SWITCH BUTTON [top]
1. Remove the side handle.
Unscrew and remove the side handle from the grinder.
2. Remove the guard.
Loosen the lock-screw on the guard assembly.
Rotate the guard assembly to disengage it from the housing.
Remove the guard from the grinder.
3. Remove the gear housing.
Remove the (4) screws from the gear housing.
Separate the gear housing from the motor housing.
4. Remove the rear cover.
Remove the (1) screw from the rear cover.
Slide the rear cover away from the motor housing.
5. Disengage the motor brushes.
Use a pick to (gently) lift the brush spring from the back of the carbon motor brush.
Reposition the brush spring alongside the motor brush (against the brush holder).
Pull (gently) on the wire lead to disengage the motor brush from the armature.
Repeat this step to disengage the second motor brush.
6. Remove the armature assembly.
Slide the armature assembly (which is attached to the gear housing cover) out of the motor housing.
7. Remove the baffle plate.
Remove the (2) screws from the baffle plate.
Slide the baffle plate out of the motor housing.
8. Remove the switch button.
Press and hold the switch button in the off position (toward the rear of the grinder).
Press the switch lever toward the front of the grinder (toward the switch button) until it "clicks" and disengages the switch button.
Remove the switch button from the grinder.
INSTALLING THE NEW SWITCH BUTTON [top] 9. Install the switch button.
Press and hold the switch lever (from the rear of the grinder) all the way forward (toward the front of the grinder).
Pass the hook on the new switch button through the opening on the motor housing.
Press the switch lever onto the hook on the switch button (from inside the grinder).
Release the switch lever (from the rear of the grinder) to engage the hook and secure the switch button.
REASSEMBLING THE UNIT [top] 10. Reinstall the baffle plate.
Install the baffle plate into the motor housing and align the mounting holes.
Secure the baffle plate with the (2) screws.
11. Reinstall the armature assembly into the motor housing.
Slide the armature assembly into the motor housing.
Align the gear housing cover with the motor housing.
12. Reinstall the gear housing.
Install the gear housing onto the grinder (aligning the mounting holes with the gear housing cover and the motor housing).
Secure the gear housing to the grinder with the (4) screws.
13. Re-engage the motor brushes.
Use a pick to (gently) lift the brush spring away from the brush holder.
Position the brush spring against the motor brush.
Repeat this step to engage the second motor brush.
14. Reinstall the rear cover.
Visually inspect the wires for potential pinch-points and adjust/tuck the wires as necessary.
Slide the rear cover onto the motor housing.
Secure the rear cover with the screw.
15. Reinstall the guard.
Install the guard assembly onto the grinder.
Rotate the guard assembly to engage the mounting plate.
Secure the guard with the (1) screw.
16. Reinstall the side handle.
Install the side handle onto the grinder.
Tighten the side handle until secure.
You can't place a value on a job well done, unless you did it yourself. (Which you did.) Now you can place that value back into your own pocket. (Or into your business.) Not only did you refine your grinder at a fraction of the cost of replacement; you have expanded your skills far beyond the daily grind.
