Luckily, the pulley on the spindle assembly is not hardened. The inner / core / splined gear component IS hardened obviously but luckily the outer part I need to machine is not. So that makes it a simple matter of grinding myself a profile cutter for the lathe in HSS and setting to.
Here's the tool. The grooves just behind the cutting edges provide a nice high rake angle which is good for fine machining, particularly when you hone the edge to a razor edge.
Getting the work set up accurately in the 4 jaw is critical unless you want the thing to run with a nasty vibration. All the rotating parts on this machine are dynamically balanced, so should continue to spin quietly unless I screw this up.
I got the spindle pulley centred to within 1 thou (25um) or so which should be fine.
The roughing produced nice clean swarf and the finish cuts produced a nice bum fluff (very fine) swarf. The final width across the opening is pretty much bang on 11mm which should suit the SPZ772 belt I ordered.
The motor pulley was pretty rusty, so I scraped and brushed it before setting up and machining. This came out nicely too.
Both ended up looking pretty good:
Finally, the motor pulley was ready for reassembly onto the motor, after cleaning and brushing up the washer and bolt to remove the rust.
Refitted the bearings to the spindle drive sub assembly. I used the large machine vise to push them in straight, using ground parallels as spacers:
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