Need to modify a part by changing straight grooves for helix?

I have a cylindrical part with grooves cut into it lengthwise the whole way around, 11 total. I need to make a part with the same size grooves, but rather than have them cut straight, i need them cut in a helix. I realize that due to the helix grooves taking up more surface area (parallelogram), I'm going to have to decrease the number of grooves to get the same width. I need to figure out what angle to cut the helix to get the same groove uniform. I need the angle of cut for a ten grooved helix part down to the smallest possible number. The dimensions are, in hundreths of an inch, cylinder diameter 2.19, cylinder length 2.06, groove width .46, groove depth .19, there is a small plateau between the grooves which is .08. I need the plateau's and the grooves of the new parts to be uniform which is why getting the correct angle is so important. Please show work. Thanks.