I need to start making the pulleys for the drill press i'm building and was planning to make them for standard v belts, but got thinking what if i use PK4 belts, are they more grippy on smaller pulley?
Sure, that belt will be grippyer, but does it matter? Regular v-belts perform very well, within their design capability. There are many thousands of DPs out there that have been running the same belt for many decades. If it works, then don't mess with it.
I have a 9" SBL that was modified to run on a "J" size poly groove belt. Been using it like that for 50 years now. On its third belt. The real draw back is keeping oil off the belt. I gave up on that years ago. Seems to help for some reason.
Do little searching for "Poly Groove " . You should get lots of hits. A few will give dimensional information.
Also go to "ToolFlo's" website and download either their turning tool catalog or specialty tooling. You will have to dig thru the catalog to find it.