Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Allan,
First off don't buy Carbide drill bits if you are hand drilling the holes.  The carbide is so brittle that you will snap them off on the first hole.   Buy high speed steel, they have some flex and don't snap as often.  However they will become dull much faster.  The good news all you need is a small fine bench stone to freshen up the cutting edge.  Only takes a few strokes at the correct angle (not running of course).   I have a little fine pocket stone about  1" x3" x .5" for the task.   To use carbide you really need a very rigid drill press,  even a slight side load will snap them.

What I use is a small  1" dia x 2.5"  long brush DC motor that came out of some old piece of military gear (ie has real ball bearings and a metal case)  The shaft is coupled to a small pin chuck.  I hand hold it when drilling like you would a Dremel but because its much smaller its easy to hold in the palm of your hand with two fingers an you thumb.  I run it at 30V with foot switch, the switch shorts the motor out when released.  The result is the motor runs very fast and stops very quickly.  The 30V is not a problem because the foot switch modulates the motor on and off for each hole so the average power is lower than you would expect.    Because the motor is stopped when going to the next hole the bit doesn't  want to walk as with a Dremel.  Center the bit on the hole hit the foot switch and the hole is through in a fraction of a second, foot off the switch and the bit is stopped for positioning to the next hole.  Works great.   It helps if the pads have a small hole in the copper from the artwork/etching.  This helps assure the drill is in the center of the pad.
Photo if the link works: PCB_Stuff

 

Craig