Camshafts and gear shafts carry oil galleries that feed the lobes, journals and gear teeth. They are short, angled, small-diameter deep holes drilled in high volume — the bread-and-butter of automotive gundrilling.
A camshaft lobe needs a small oil passage from the central (or drilled) gallery out to the lobe face or journal. On a gear shaft the passage feeds a gear hub. These holes are typically Ø3–8 mm, drilled at an angle from the shaft surface or from a pre-drilled center gallery, and they must land inside the target without breaking through a flank.
| Configuration | How it works | Use case |
|---|---|---|
| Drill from center gallery out | Center bore (or hollow shaft) pre-exists; angled blind holes connect to it | Hollow / pre-bored camshafts |
| Drill from OD to center | Angled blind holes from the journal face to meet the center gallery | Solid camshafts, gear shafts |
In both cases the entry is angled and usually on a cylindrical surface, so a spot face or milled flat at the entry is standard practice before gundrilling.