A blue test shows pretty clearly that there is good contact for about the bottom half of my bt30 taper and fading to no contact at all towards upper half. Checking with blue was done with a few holders and got consistent results. This is a cheap aliexpress bt30 cartridge so im not really surprised its not perfect. This is resulting in not perfectly consistent runout every time a tool is loaded. Im waiting for a quote to see how much it is to send it out for a grind, but i think i might be able to do this myself. In the attached pic is my old z axis and chinese 2.2kw spindle. I have clearance on my machine to mount this entire assembly at an angle on my machine to grind the taper of the bt30. Couple questions before i try this. First of all, will this 24k rpm chinese spindle be up to the task? Is that rpm (or slower) suitable? It has an er20 taper so whatever grinding tool i use, it needs to have max 1/2" shaft. If it it will work, What type of grinding tool specifically am i looking for? Im assuming silicon carbide and i know about what dimensions it needs to be, just dont know where to look or what to search for.