How to make a Hobbed bolt

http://www.youtube.com/watch?v=4OEjcpbdBe0

2 pcs - 608 bearings
2 pcs - 626 bearings
1 pcs - tap screw M6

myhb - first with 0.7 groove depth
myhb1 - second with 0.9 groove depth
myhb2 - third with 1.2 groove depth