Tripod mounting threads
I have to get a mounting thread cut in a bespoke tripod I am using so that I can mount a ball head on it. I know that the threads sizes are quoted as 1/4 inch for the camera and often 3/8 inch for the mount of the head to tripod. But what I dont know is what type of thread to tell my metal turner to cut. Can anyone enlighten me as to exactly the specification of both of these threads please?