Roomba 5 series green CHM (cleaning head module) quiet replacement gear set. Note different Roomba models use different gears.
Herringbone involute tooth profile with zero backlash.
This gear set is designed for vic7767 ball bearing hair reduction modification circa 2009 (http://www.robotreviews.com/chat/viewtopic.php?f=1&t=11591)
The transmission has 6 gears and two of them are identical, I included only 5 files, you need to double print roombaherringR.stl
The three idlers gears roombaherringR.stl roombaherringL.stl roombaherringR.stl
are installed with the smaller and deeper circular depression facing you.
The axle hole is very slightly undersized. The holes need to be straight and have minimal shaft clearance. Very carefully run a drill through the axle holes.
The gears are a bit tricky to install because one at a time is not easy with a herringbone profile with zero backlash. You need to engage all the gears and slide them down all the shafts at the same time or fiddle with them almost falling off the shaft if attempting one at a time.
Grease only the axles and run them in for 10 minutes or until the gear surface finish improves and the transmission runs smooth, then grease the gear faces. If you have an adjustable bench power supply you can run in the gears with the transmission cover open because the herringbone profile tends to track the motor mounted gear position.
In the photo of the closed transmission you can see I put tape over the shaft bushings. This is an additional mod of mine that keeps the grease in and the hair out, not actually required.
Hobby King PLA
motor shaft gear solid others 15%
Designed in Fusion 360 high STL refinement
using the Helical Gear Generator app by Ross Korsky
You need to double print one of the gears.
Cetus3D MK2 0.4mm nozzle
Fine (best print setting)