Replies

1. 
   Steinmetz | Aug 08, 2003 04:15am | #1

   Asennad,if you buy a good pair of safety goggles,(wrap around is best)

   and buy a medium grit  4" round 'Cup' wheel with 1/2"center hole (Or,bushing)

    Buy a 1/2" arbor to fit your 3/8" drill  Sears sells excellent arbors but doesn't carry cup wheels.

    Since this method of drill grinding is easily done on the side of the wheel, either a regular flat wheel or a cup wheel will do. (Sears has the flat type)

   If you examine a typical new twist drill, You can imagine the point looks somewhat like the point on a pencil.

   If you held the dull drill bit to the wheel, and "twirlled"it evenly arounda few times you created a nice even conical point.(like a pencil's)

   While this looks to the eye as a copy of the new bit, it won't cut a hole no matter how hard you push the rotating bit.

   "What's wrong,?"  you ask.The two lands each have a cutting edge 'zackly like the new bit you think.

   NO! the two cutting edges are not doing their job   because they are exactly in line with the trailing 'lands'

   In order for any cutting tool to do it's job of peeling off metal, It's cutting edges must be prominant: that is, sticking out beyond the lands.

   If you daub a blue magic marker on the lands, (The better to comparethe next trick)

   You are ready to twirl those lands again, but now as you twirl, tilt the bit back a bit (at the same time) to grind off the material beyond the leading edge and going gradually deeper and deeper.

   After a few trials (And errors) You will do this in your sleep. You'll never have to pay for new bits again, as most bits can be resharpened many many times.

   One important bit of bit advice, is to hold the grind stone directly in front and level  (Like a bench grinder)  and position the leading edges so when you start grinding, the edge is facing you while it is also VERTICAL 

   (Imagine a plumb bob,s line hanging there)

   Twist the bit toward your right. and under cut the land more and more

   Practice practice and compare and compare with the new drill bit.

   If you want to cut wood or soft stuff, grind a steeper angle (Like a pencil's)

    Iron and steel require a stubby angle.

   Do the two lands equally and hold the bit steady as you do the other land. 

   Let me know how you're doing, and I'll tell you how to sharpen bits for brass and copper too. Stein.

1. 
   Senna | Aug 08, 2003 10:29pm | #3

   safety goggles - check

   flat wheel - check

   that is, sticking out beyond the lands. - got it

   "You are ready to twirl those lands again, but now as you twirl, tilt the bit back a bit (at the same time) to grind off the material beyond the leading edge and going gradually deeper and deeper.

   One important bit of bit advice, is to hold the grind stone directly in front and level (Like a bench grinder)

   Twist the bit toward your right. and under cut the land more and more"

   OK I have the drill and round flat stone set up hanging off my work bench. When I try to sharpen the bit I get a rounded off point and the under cut doesn't look like it is undercut. How do I hold the drill, horizontal and but angled to the face of the grind stone? Do I go down to form the undercut?

   Edited 8/8/2003 3:30:12 PM ET by ASENNAD

1. 
   Steinmetz | Aug 08, 2003 11:23pm | #4

   ASENNAD, THAT'S RIGHT DROP DOWN ON THE /AS YOU ROTATE THE BIT.

     Bobress say's it more succently than I, and although  he does it from trailing edge to cutting edge, I do it from cutting edge to trailing edge.

   I like his rationale,  so i'm gonna change my evil ways.

   You should too, or try both??

   Thanx for the prompt reply and good luck.Stein.

   Thanx also to Bobkress, for enlightening me (An old dog who learns new tricks)

1. 
   robkress | Aug 09, 2003 01:31am | #5

   No problem but I can hardly take any credit.  I am just a young dog who happened to be in the presence of an old master who taught me a thing or two.  And in fact, with the method I described, it is sometimes necessary to "dwell" a little at the leading edge to make a very small flat (almost too small to see).  Otherwise, especially for metal work (brass in particular), the grid is incredibly TOO sharp and cuts too aggressively (if you can believe that).

   Rob Kress

1. 
   Steinmetz | Aug 09, 2003 03:23am | #6

   Bob,You have been very helpfull. I do believe we will have converted a new 'Old hand' (maybe more?) with these postings.

    Before your post appeared, I was just finishing up a response to our new drill sharpenerAsennad .I posted it but then lost it to the ether? 

    Maybe I should get a keyboard with those giant buttons (like my wall phone) to fit my fatfingers? Stein.

   Edited 8/8/2003 8:25:27 PM ET by steinmetz

2. 
   robkress | Aug 08, 2003 04:07pm | #2

   I have a drill doctor which is excellent but for an inexpensive solution I like an attachment to a drill.

   For sharpening, I twist from the trailing land to the leading cutting edge.  Let me explain a little more.  Imagine a perpendicular line to the grinding face coming out of the grinding wheel.  Then, hold the drill bit with the but end left of the perpendicular line at the proper rake angle for the drill bit and horizontal to the ground.  Now if you were to twist the drill bit counter clockwise it would make a perfect pencil point.  This is the perfect position to be in.

   Here's where practice comes into play... To make a good point with the trailing landing "relieved" from the cutting edge:

   twist counterclockwise

   at the beginning of the twist on a landing, push the drill bit into the grinding stone hard to grind a bit of material and lighten up this pressure as you twist.  By the time you twist over to the leading edge, you should be barely pushing the drill bit to the stone.  And the stone should be rotating down onto the leading edge of the drill bit (not spinning from the trailing land off the edge of the leading edge).  By grinding this way, you reduce the chance that the metal will "roll over" the cutting edge and make sort of a blunt rounded burr on your cutting edge.  This happens because the metal at the grind heats up and starts to flow.  If you are then grinding from the trailing land to the leading edge, you essentially roll this metal flow right over the edge.

   Also by grinding in this method, you can very accurately control the temperature of the grind and line of your grind (because you can see it very clearly).

   Once you have the technique down, you will find that you "dress" your drill bits more than grind them.

   And of course you can do the converse of this method staring at the leading edge and pushing harder as you twist clockwise.  But I find the above method gives me more control and to be more accurate.

   Good luck.

   Rob Kress