You can have a go but trying to cut a helical scroll on a lathe is not the easiest as the larger lead you generate [i.e.. your scroll vs a screw thread] the mechanical set up means you need the saddle movement to turn the chuck? Others will come along with more details I'm sure, also rough the bore do your groove & finish the bore as the last operation.

Tony

Hi Martyn

I did something similar for a Bultaco gearbox bush and as Tony suggests I had to drive the lead screw because using a mandrel handle in the spindle didn't feel right, something was going to strip. My lathe is the ubiquitous Chinese mini lathe with plastic change gears.

HTH

Cheers Michael

If you wanted to make it complicated you could watch this:

Producing a shallow thread with a 10 mm pitch will be difficult.

I would prefer Graham Meek's suggestion of turning a plain groove on the line of the grease inlet, and relying on the clearance to distribute the grease.

To my mind this will have advantages

The entire bush / kingpin interface will be lubricated.

The grease will fill any clearance and improve alignment/fit..

Having grease oozing from the ends of the bush should reduce the risk of water ingress.

Howard

Set up to screwcut a coarse pitch and drive the leadscrew. Constant result and if you need to make th ecut in more than one pass each will follow the same path.