internal spline into a square block of metal (steel) like this: image 1 image 2
I'm trying to figure out if i have a 6"X1.5"X1.5" piece of steel, in which i need to put a 5/8 OD spline centered in the middle, how would one be able to do this??? How would i be able to heat forge the spline shape into the piece??? Or is this something that blacksmithing can't do???