iRobot Roomba 5xx 6xx 7xx Gray CHM mod
Roomba Gray CHM mod
How did I modify 5xx CHM with bearings
DISCLAIMER - Important!
Suggested tools and materials:
- Phillips head screwdriver
- Old toothbrush or some other small cleaning brush
- Lithium grease
- Vacuum cleaner (to be use it in each step where you find dust and hair buildup. Be careful not to vacuum small parts as well.)
- Electric screwdriver or drill
(This will be used as a kind of lathe that holds the gear wheel in order to contract its diameter.)
- 3.0mm drill
- Fine tooth blade arc hand saw
- Set of files, straight and round.
- Screw and nuts 4-40 or M3 to retain the small gear wheel to the drill.
- Step drill bits
or any other tool that can help expand the housing holes diameter such as grinding stone, awl or a file.
- Swivel burrs removal tool.
(This is a great tool to help in expanding housing holes.)
- Vise grips or a bit handle
(This is to hold the drill bit etc. It is advised to expand the holes by hand and not with an electric drill to gain precise and more controlled process.)
- 3 sealed ball bearings with the following dimensions:
(in x out x thick, Metric system)
– 6x10x3 mm (for motor gear)
– 10x15x4 mm (for small beater brush gear)
– 15x21x4 mm (for large bristle brush gear)
To save you time, I have prepared for you a set of the 3 needed bearings that you can purchase right now. Click the following Buy Now banner to review the set and purchase.
B. Disassembly of the robot and modding the gearbox.
Note: since most of the screws are screwed to plastic bosses, it is advised to use hand screwdriver for fine torque control.
11. Separate the Gray CHM module from the Blue external frame by first spreading its ‘wings’ (one after the other) and by rotating the CHM inner Gray case.
Be careful not to use excessive force.
Though the image shows the module prior of PCB/tension cable disassembly, you should perform this step AFTER you disassemble the above PCB/tension cable.
18. Now contract the gear wheels cylinder diameter.
Modified diameter should meet the inner diameter of the relative bearing. Mating should be tight.
Motor wheel needs to be contracted and on both beater and bristle wheels we need to first remove its external ring wall and then contract its diameter to meet the bearings
19. Diameter contraction is done here with the help of an electric screwdriver and a file.
First image shows the motor gear wheel which is held with a 4-40 screw
Second image shows the ring wall removal with an arc saw
Third image show drilling the bristle wheel in order to allow restrain it to the drill.
If possible, prefer using table drill or a lathe for perfect centering and alignment
Pay close attention not to file too much !
Check fitting to the bearing often till you reach needed diameter.
Don’t file the gear, just its mating cylinder diameter !
Make sure that file’s flat surface is pointing towards the gear.
- Motor wheel cylinder size fits bearing inner diameter of 6.0mm. Stop modifying at 6.3mm
- Beater wheel cylinder size fits bearing inner diameter of 10.0mm. Stop modifying at 10.3mm
- Bristle wheel cylinder size fits bearing inner diameter of 15.0mm. Stop modifying at 15.3mm
- Hole size for motor wheel fits bearing outer diameter of 10.0mm. Stop modifying at 9.7mm
- Hole size for beater wheel fits bearing outer diameter of 15.0mm. Stop modifying at 14.7mm
- Hole size for bristle wheel fits bearing outer diameter of 21.0mm. Stop modifying at 20.7mm
D. Voila – you now have a working iRobot Roomba with modded Gray CHM gearbox.
Have fun and enjoy your Roomba, Avi
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