Re: Drill bit sharpening help

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Posted by Tim Daley(MI) on July 21, 2018 at 07:29:03 [URL] [DELETE] :

In Reply to: Re: Drill bit sharpening help posted by TheOldHokie on July 20, 2018 at 18:30:45:

Yes, that is true, however, if you are using a lathe and your set up isn't absolutely perfect, with tool aligned dead nuts center, square and perpendicular in X, Y, and Z axis, even a new drill will cause it to only cut off one flute. New drills out of the box these days can be poorly sharpened as well. the art of hand sharpening should be taught in every High School, trade school, and college machine tool class in the USA. One problem is that the instructors never were trained properly. Some younger ones these days had always used drill sharpening devices and never learned the hand method. It's like the machine tool industry today whereby some kid on a tube using CAD/CAM software thinks he is a CNC Programmer. If he has never had to learn the actual NC G-Code, write an actual working program out by hand, and has had no hands-on machining experience, he has no clue what feed and speed are all about. Back in the day, a real NC Programmer (like me) had to learn binary coded decimal, how to trig out angles and then add in tool nose radius compensation constants, how to generate arcs and partial arcs with TNRC and then enter the absolute values in the G-CODE punched tape for the machine control/tape reader to operate. CNC machines do not use punched paper or Mylar tape anymore, and CAD'CAM systems will use ATNRC codes too BUT if the "programmer" doesn't know what the true value should be, relies on whatever info he inputs, expect errors. By teaching hands-on with Bridgeports and engine lathes, a student needs to get and understand the 'feel' of feed and speed, what torque is, and what too much or too little of any one will do. One example, by hand drilling a piece of steel on a Bridgeport, one can feel what happens when they try to feed the tool too hard or fast. Also, temperature affects everything too. Workhardening is a term you never hear anymore. Ask any modern CAD/CAM CNC "programmer" what the sine of 30 is or what a G30 command is for. I'd bet he can't answer you.

Tim Daley(MI)

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