The standard acrylic involute gears were driving me nuts with their incessant CLICK-CLACK CLICK-CLACK noises, so I designed these herringbone gears to replace them. Now I can't hear my printer from the next room :)
The motor gear has a 'floor' to help you position the grub/nut easily and precisely. The rebate for the nut has also been set back from the shaft a bit to make it easier to fit than ever.
An additional advantage is that they are constantly in mesh, so there is no slack to take up when reversing direction (if you use M227, this happens hundreds/thousands of times each print!) so you will have cleaner prints too.
Print using your favourite settings (no support material required) however do NOT print with PLA as the extruder motor heat will soften the drive gear and the grub nut will come loose.
When installing, replace the split-ring washer on the extruder drive shaft with a new M8 flat washer, and place the split-ring between the original washer and nut. This keeps everything from coming loose without letting the split-ring tilt the driven gear.
Lastly, face the grub slot up for aesthetics - not only will it hide the slot, but from the front of the machine the driven gear will look like arrows pointing and moving towards the filament.