How to Make a Hobbed Bolt

How to make a hobbed bolt using a drill press and M4 tap. If you don't have a grinder, you can chuck the bolt in the drill press and use a dremel tool to cut the groove. The groove gives the tap something to bite into. fwiw, I'm CodeCreations* on #reprap. Please pardon the focus hunting and lighting -- first video with the DSLR... Here's a step-by-step description of what you see me doing in the video: 0:10 - Mark the bolt where the filament will be 0:19 - Chuck the bolt into a drill 0:34 - Grind a groove along the marked line 1:02 - Re-mark the location of the filament 1:21 - Chuck the tap into the drill press 1:51 - Put the bolt in two bearings 2:00 - Apply cutting oil to tap (probably not necessary) 2:25 - Press bolt against turning tap at the marked line until teeth are sharp. (It will turn by itself once the tap starts grabbing.) 3:07 - (Clear out gunk with compressed air if necessary.) 3:16 - Test for sharpness by carefully examining. I put my fingernail against it to see if it grabs well. 3:24 - Close-up view of finished bolt 3:30 - Tools used and end credits Tools: Ryobi DP120 12" benchtop drill press, Central Machinery (Harbor Freight) 8" Bench Grinder, M4 tap, cutting oil, two 608 bearings. The drill press was set to 450 RPM. Music: "Me Robo El Show" by Alex, 2011 - Licensed under Creative Commons Attribution (3.0) http://ccmixter.org/files/AlexBeroza/... (BTW: Yes, I'm aware that the lyrics have nothing at all to do with making a hobbed bolt, but this is a great mix of an excellent vocal by Farina, and so I used it anyway.)