Deep Hole Drilling for EV Motor Shafts: What I'm Seeing on the Shop Floor

I’ve been seeing more EV motor shaft work in the last couple years. The pattern is consistent: a shaft maybe 300-600mm long, 30-50mm OD, with a through-hole of 10-25mm that needs to be straight and smooth over the full length. The reason is weight reduction. A hollow shaft spins up faster and puts less load on the bearings than a solid one. And the balance is better — which matters when the motor is spinning at 15,000 RPM or more. (If you’re more familiar with gun drilling solid shafts, the hollow ones have their own quirks.) ...

June 11, 2026 · Engineer at the Deep Hole