EA, I agree the sharp edge on the OD of that 15* cutter isn’t good.
I’ll be interested to see if there are any gains to come from putting a radius in the corner(clay).
The cutter I use for that relief cut is 20* with a radius on the outer edge.
I finally bought a couple single cut 15 degree cutter after being told to do so by you and my fishing buddy that bought my old flowbench. It took me awhile to properly use it with his coaching. I thank you for the recommendation. Honestly since it’s racing season and other priorities are going on I used it after I hand formed the chamber then just used it to fix the bottom radius and add the 15 degree top cup. I’ll do the second head the same way but for now on I’ll cut the 15 first shaping the chamber and giving me a FULL 15 degree then do my 4 angle cut to meet it. This may sink my valve .010-.015. Thanks again. I still have to do what I do to the chamber above and below the 15 degree cut but it will sure take some labor out of it.