i have described how to make concave knurls before. I just run the blank wheel against a tap that is rotating in the lathe. The concave surface of your knurl blank must pretty well match the size of the knurl at its diameter at the tips of the teeth,or you ill get a messed up knurl. I make them from 01 or W1 drill rod,and harden after completion. Draw the color to a dark brown or purple.
By tilting the blank knurl blank,you can make the rope knurl type of knurl. I use a round ended knurl holder that I make,so it can be tilted in the tool post holder. I can get away with about 20º tilt towards the right. Too much tilting,and the knurl will start getting "serrated" by the back side of the tap's teeth. Tilt the knurl wheel a LITTLE bit back towards the left,and you can make the knurl grooves perfectly vertical. Otherwise,the knurl grooves will have a bit of tilt to them,as if they were threads,since taps do cut threads,of course,and the threads do have a bit of tilt so they'll screw into a hole ! I hope you can make sense of my rather poor description.