I finished my knurling tool tonight. Thank you for sharing the designs and plans.
Two additional notes:
1) I did this entirely on a grizzly mini-mill (and horizontal bandsaw). So if all you have is a mini-mill, like me, you can do this! Just take your time.
2) I adapted the idea for the QCTP mount to instead slide into a lantern tool post (about 3/8 x 1-1/4"). So far this is working fine, I did one test knurl and then knurled a thumb nut for the knurl itself. So if you have a lantern tool post and no QCTP, you can do this!
Edit: Adding note 3) I believe the original design welded the pivot pin for the cam jack. I could have built didnt want to weld, then grind smooth, etc. So far I've just placed the pin in the slot, and run with it (no fastening). I did apply red loc tite tonight to see if that'll hold the pin - merely for convenience sake. An expoxy like JB weld would surely work. So if you don't have a welder, don't let that step intimate you!
Edit: Adding note 4) Although I did purchase and use a ball end mill to cut the slots for the cam pivot pin, in retrospect I'm not sure this was necessary. I believe with a sufficiently long square end mill, the same technique shared by the original author to create 3/4" radii for clamping nuts, could be used to create these small slots. In the event it saves a tool purchase beyond budget. Perhaps with a solid spacer to avoid an interrupted cut a sharp drill could even be used as Hawkeye stated above.
I did notice the arms tend to pull to the side a bit. I believe someone in the thread mentioned adding support to prevent that. May not be a bad idea. Though my first 2 knurls in steel of unknown alloy look great.
I also noticed the need to hold the arms apart to position them onto the workpiece. Not a big deal. May look into spring options at some point. Just position the knurler arms lightly on the work piece with the lathe off. Seems to work.
Thanks again for sharing the designs and plans!