Roomba CHM cleaning

How to clean Roomba’s Cleaning Head Module

How did I clean iRobot Roomba 560 vacuum robot CHM gear box?

One result of a relatively cheap (or poor) product design and manufacture is worn to its moving components.
This is the case with the design of the iRobot Roomba 5xx vacuum robots, especially in its CHM (Cleaning Head Module).

This module holds the 2 rotating brushes (bristle brush and beater brush). The mating point of the bristle and beater brush to the gear mechanism (that transfer power from the CHM motor) relies on plastic to plastic friction. This mating point is not sealed, allowing dust & hair to pass through the gap straight to the gear mechanism.

Dust and hair build-up on the gear wheels causes it to slow down and increases friction until it stucks and even prevent the motor to spin. In addition, this friction causes extra worn to the circular mating holes, expanding the gap and eventually causes the plastic part of the CHM to melt around the holes.

In order to avoid this situation, it is advised to clean the CHM gear housing. Cleaning frequency depends on usage and the amount of hair/dirt buildup.
In case your Roomba brushes stopped rotating and/or you get the error code #2 (“Uh-Oh” + 2 beeps), it’s time to clean.

Start with the bristle brush and with the beater brush. Clean its bristles/flaps, take off each of the brush side bearing and clean the metal pin. If you have cleaned both the bristle brush and the beater brush but it is still not working, now is the time to go deeper and clean the CHM gearbox, hoping the motor is not damaged.

Let’s start the step by step cleaning process of the Roomba CHM gear box.

Note:
This guide shows the Roomba 560 with Red CHM, but it is relevant for other 5xx 6xx 7xx models as well that uses the Green or Red or Gray type CHM. Slight differences in disassembly process are needed though, but general concept remains.

DISCLAIMER - Important!

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A. Preparing for the fix:

Needed tools and materials:

Phillips head screwdriver
Used (or new) toothbrush or some other small brush
Lithium grease
Vacuum cleaner (not mandatory but recommended)
Use it in each step where you find dust and hair buildup but be careful not to vacuum small parts as well.

B. Disassembly of the robot and cleaning of the gearbox.
Note: since most of the screws are screwed to plastic bosses, it is advised to use hand screwdriver for fine torque control.

1. Place the Roomba top down on a solid work surface.
Remove the screw from the rotating side brush and gently pull it out.

2. Remove the four screws holding the bottom plate and remove the plate

3. Take out the battery, lift it using the 2 plastic tabs.
Take out the dust bin.

4. Unscrew the CHM 4x screws and take it out by pulling it gently.

5. This is the CHM – “Cleaning Head Module”, we need to access its left side.

6. Open the module top door and take out the bristle and the beater brush

7. This is the mating area where bristle brush and beater brush meet the gearbox.
The gap between the gear wheel cylinder to the plastic housing is seen clearly.

8. Unscrew the module’s case frame side panel. 4x screws.

9. Unscrew the gearbox side panel 6x screws.
Gently open the side panel to get to the gearbox.

10. Vacuum / clean the gearbox, pay attention not to vacuum the gear parts.
Record the gear wheels size and position for easy assembly later on.

11. Disassemble the gear wheels, clean it well and check that nothing is broken.
You can clean it with warm water and soap and use a small brush to clean between the teeth.

12. Check the gear holes in the plastic wall. Here you can see a slight damaged/worn wall.
If your Roomba is in this condition or worst, you should consider modding it with bearings.

See my CHM mod page for the bearings modification.

13. Dry the gear wheels, lubricate each with Lithium grease and reassemble the gear wheels.

C. Assembly – assemble all parts in reverse order to what is listed above.
If you have completed the assembly and left without any screw,
hit the Clean button and see if your Roomba starts to clean…

D. Voila – you now have a working iRobot Roomba with a clean gearbox.

Have fun and enjoy your Roomba, Avi

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