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  How to Replace the Armature on a DeWALT Angle Grinder (Model D28402)

Video

Tools & Materials

Fix Factor: Easy Duration: 30 minutes Frequency: As necessary Tools Required: Phillip's screwdriver, standard screwdriver, long-nosed pliers, torx drivers, rubber mallet Part #: N384369

How to Replace the Armature on a DeWALT Angle Grinder (Model D28402)

Replacing the armature on a dewalt grinder The Facts

If spinning wheels and service bills are grinding at your nerves, it's time to face the fix. Whether you are a grinding professional or a seasonal grinder, eReplacementParts.com provides the parts, procedures and facts you need to fearlessly fix what fails you.

The armature is the central component within a grinder's electric motor. It is composed of a steel shaft, copper windings, and a series of commutator bars (through which the carbon brushes transfer electricity). If the grinder is overloaded, the copper windings can become extremely hot. If this occurs repeatedly, the insulation surrounding the windings can melt and the armature will fail.

This article will show you how to easily remove and replace the armature on a DeWALT D28402 angle grinder.

Let's get started.

The Fix   REMOVING THE ARMATURE [top] 1. Remove the side handle.

Unscrew and detach the side handle from the grinder.

Remove the handle

 

  2. Remove the guard.

Raise the guard latch.

Raise the latch

 

Rotate the guard until the lugs disengage.

Rotate the guard

 

Remove the guard from the grinder.

Remove the guard

 

  3. Remove the top half of the handle assembly.

Remove the (5) retaining screws.

Remove the screws

 

Remove the top half of the handle assembly.

Remove the top half of the handle

 

  4. Separate the handle from the field case.

Remove the paddle assembly.

Remove the paddle

 

Remove the lock-on button assembly.

Remove the lock-on button

 

Separate the handle from the field case.

Separate the handle

 

  5. Disengage the motor brushes.

Use long-nosed pliers to detach the brush wire from the terminal.

Pull the wire

 

Use long-nosed pliers to lift the brush spring away from the brush arm.

Raise the brush spring

 

Lift (rotate) the brush arm assembly away from the armature.

Lift the arm away from the armature

 

Repeat this step to disengage the second motor brush (on the opposite side of the grinder).

Repeat this step on the other side

 

  6. Remove the separator/fan.

Press and hold the spindle-lock button (on the gear case) to prevent the motor from spinning.

Lock the spindle

 

The separator fan is REVERSE-THREADED; rotate the fan in a CLOCKWISE direction to loosen it.

Loosen the fan

 

Remove the fan from the armature shaft.

DESCRIPTION

 

  7. Remove the gear case assembly.

Remove the (4) gear case retaining screws.

Remove the screws

 

Using a flat-blade screwdriver, gently pry the gear case assembly away from the field case.

Pry the case apart

 

Slide the gear case assembly (and armature) out of the field case.

Remove the assembly

 

  8. Remove the armature from the gear case.

SPECIFIX: During factory assembly, the armature is pressed into a bearing within the gear case assembly. The two components can generally be separated by hand. However, particularly “stubborn” connections may be broken by tapping the rear shaft of the armature with a rubber mallet.

Separate the armature from the gear case

 

Firmly grasp the components on each side of the connection (one hand on the armature; one hand on the gear case).

Grasp the two components

 

Apply slight outward pressure (as if breaking a wooden branch) while pulling the two components away from each other.

Apply pressure to sides

 

Remove the armature assembly from the gear case.

Remove the armature

 

  INSTALLING THE NEW ARMATURE [top] 9. Install the armature assembly.

Insert the new armature assembly into the gear case (rotate the assembly until the pinion gear engages the bevel gear).

Insert the armature

 

Align the tabs on retainer plate with the slots on the gear case.

Align the tabs

 

Press the two components together firmly to seat the bearing in the gear case. Tap the rear shaft of the armature with a rubber mallet (if needed).

Press the components together

 

  REASSEMBLING THE UNIT [top] 10. Reinstall the gear case (and armature) assembly into the field case.

Slide the gear case (and armature) assembly into the field case.

Slide the assembly into the field case

 

Secure the gear case with the screws.

Secure the gear case

 

  11. Reinstall the separator/fan.

Press and hold the spindle-lock button (on the gear case) to prevent the motor from spinning.

Lock the spindle

 

The separator/fan is REVERSE-THREADED; rotate the fan in a COUNTERCLOCKWISE direction to secure it to the armature.

Install the fan

 

  12. Re-engage the motor brushes.

Lower (rotate) the brush arm assembly into position above the armature.

Lower the brush arm

 

Use long-nosed pliers to re-engage the brush spring.

Engage the brush spring

 

Reattach the brush wire.

Connect brush wire

 

Repeat this step to re-engage the second motor brush (on the opposite side of the grinder).

Repeat step for the other brush

 

  13. Reattach the handle assembly to the field case.

Connect the lower half of the handle to the field case (when properly aligned, the two components should “snap” together).

Connect the handle

 

Tuck the wires into the designated channels inside the handle.

Tuck all of the wires

 

  14. Reinstall the lock-on button.

One side of the lock-on button contains a small tab. This tab should be installed facing the armature.

Lock-on button tab

 

Install the lock-on button into the handle.

DESCRIPTION

 

  15. Reinstall the paddle assembly.

Install the paddle assembly into the handle; ensure that the “tail” is positioned above the switch button, and the “fulcrum” is seated within the recess in the handle.

Install the paddle

 

  16. Reinstall the top half of the handle assembly.

Partially install the top half of the handle assembly.

Partly install handle

 

Align the posts (on the paddle and the lock-on button) with the recesses in the top of the handle.

Align the posts

 

Before securing the handle with the screws, test the paddle and the lock-on button for proper functionality.

Test the buttons

 

Secure the handle with the screws.

Secure the handle

 

  17. Reinstall the guard.

Install the guard onto the grinder.

Install the guard

 

Press and rotate the guard to engage the lugs.

Rotate the guard

 

Lower the latch to secure the guard.

Lower the guard latch

 

  18. Reinstall the side handle.

Thread the side handle onto the gear case assembly.

Install the side handle The Finish

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.

Find your next fix here.   [top]

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