We wanted the pivot on a new folder model to run on bearings we control, not on whatever OD and thickness we could source. So we cut the cages ourselves.

Material is C360 brass sheet. It sits in a 3D-printed workholding frame we made for this job — the frame indexes the plate and clamps it at eight points, so it stays flat through the whole run. Coolant is a steady low-pressure flow, enough to clear chips out of the pockets without washing the small parts around. Ball pockets and outer profiles both get cut with a 0.8mm carbide end mill. Small tool, so the pockets come out clean and the parting pass leaves very little to clean up.

A full plate comes off the machine as one panel with the cages still attached. Then it's deburring, which is the slow part. Nothing technical about it, just time.

Balls are silicon nitride. They seat into the pockets and stay put during assembly without any retainer.

The obvious question is why bother when a bag of bearings costs almost nothing. Answer is fit. When the pivot boss, the washers and the lockup are all made in-house, having the bearing dimension as a variable you set yourself instead of one you design around saves a lot of shimming later.

Anyone else here cutting their own cages? Curious what material and ball combination you've settled on, and whether you run them dry or with anything on them.

Disclosure: we make knives commercially (Noblie Custom Knives), so this is shop work, not a hobby build.

Machining custom brass caged thrust bearings for our new folder model