This job is extremely labor-intensive.
If the craftsmanship isn't good enough, it won't meet standards no matter how it's made, and when assembling, it might not fit. Forcing it together can cause shaking or scraping issues, wearing down the equipment.
He's getting better at grasping the spatial structure of geometrical bodies, but the requirements for making bearings are still too high.
The two bearings are more than a meter apart; inserting the spindle must ensure the size fits just right, so it doesn't wobble when rotating.
Each bearing consists of a large steel ring surrounding a smaller steel ring.
His lathe isn't precise enough, capable of processing only a rough form, while finer adjustments depend entirely on his hands.
He needs to do a lot of observing, trying, grinding, and adjusting.
He also processes the gear shafts with the lathe first and then adjusts them by hand.
All of this is extremely painstaking work.
