Is it possible to use the Openbuilds XYZ probe to find work zero point with a 60 deg. vbit or do I have to use a type of end mill (say 1/4 inch) to find the zero ?
Use a regular endmill (or even better a precision gage pin https://www.grainger.com/product/VERMONT-GAGE-Class-ZZ-No-Go-Pin-Gauge-0-5VUG0 ) to set X and Y, then swop in the V-Bit and probe Z-Zero. Amazon also has a couple "gage pin 1/4 inch" results