Just completed a large diameter clam shell type knurler for my quick-change tool post.
The type that is pushed against the part being knurled I believe applies excessive load on the lathe spindle bearings.
I fabricated this item to knurl the bodies of two tailstock die holders. I have a smaller version I made some time ago but it was not large enough to encompass the part being knurled.
The second and larger version is very similar to the first one except the arms are machined from 4130 steel for added strength and a hex nut was utilized instead of the knurled wheel used on the smaller version.