simonr Posted May 21, 2006 Share Posted May 21, 2006 This is a fairly frequently asked question, but is difficult to explain in words. I've drawn the diagrams below in the hope that it will help. Although the subject of sharpening drills is HUGE, what I've drawn below will do for 99% of holes through most materials, especially mild steel. If it doesn't work so good on a particular material, try making the drill bit more or less pointy. If the drill bit keeps going blunt, slow down the drill speed. And my top tip for easier drilling with big (>10mm) bits: Si Quote Link to comment Share on other sites More sharing options...
LR90 Posted May 21, 2006 Share Posted May 21, 2006 Good post Si. Not seen the concave/convex tip before, thanks Quote Link to comment Share on other sites More sharing options...
istruggle2gate11 Posted May 21, 2006 Share Posted May 21, 2006 Although the subject of sharpening drills is HUGE, Nice one Si, I hope this makes it to the Technical Archive Web thinning should also be considered when a drill is getting shorter due to regrinding as the shorter the drill the thicker the web gets, giving a much greater length chisel edge which in turn creates more heat and requires more power to drive. Be carful when thinning the web (reducing the chisel edge) it is not unknown for the drill bit to split vertically up the drill if the chisel edge is too small. Quote Link to comment Share on other sites More sharing options...
simonr Posted May 22, 2006 Author Share Posted May 22, 2006 Nice one Si, I hope this makes it to the Technical Archive Web thinning should also be considered when a drill is getting shorter due to regrinding as the shorter the drill the thicker the web gets, giving a much greater length chisel edge which in turn creates more heat and requires more power to drive. Be carful when thinning the web (reducing the chisel edge) it is not unknown for the drill bit to split vertically up the drill if the chisel edge is too small. Cheers! People have talked about drills splitting up the web - but I've never seen it! Must try harder! Agree re the web getting thicker along the length of the drill - but figured most people will loose or break the bit before it becomes an issue & decided to keep it as simple as possible! Si Quote Link to comment Share on other sites More sharing options...
MogLite Posted May 22, 2006 Share Posted May 22, 2006 Good post Si. Not seen the concave/convex tip before, thanks Nah me neither - thats a good tip <groan> I sharpen my drills on a linisher, I find it a lot easier than the side of a grinder wheel. Quote Link to comment Share on other sites More sharing options...
istruggle2gate11 Posted May 22, 2006 Share Posted May 22, 2006 Nah me neither - thats a good tip <groan>I sharpen my drills on a linisher, I find it a lot easier than the side of a grinder wheel. I used to work with a guy who could grind a ø6" drill to perfection on a linishing belt, and then add chip breakers and web thinning with a 1mm grinding cut off disc! Quote Link to comment Share on other sites More sharing options...
Phil Hancock Posted February 16, 2012 Share Posted February 16, 2012 Another trick for checking the included angle of the cutting edges is hold 2 hexagon nuts together flat to flat and hey presto an angle gauge. I have seen a drill split up the web, it was a brand new 3" diameter job being used for the 1st time. Quote Link to comment Share on other sites More sharing options...
bushwhacker Posted February 17, 2012 Share Posted February 17, 2012 Hello there There is a small drill bit holder that can be bought. It holds/clamps the bits at the correct angle, it has variable angle settings and I have sharpened up to 16mm (reduced shank) with no problems it might do bigger but 16 is my largest. It might be a Draper tool. I could never get the angle correct before for sharpening. Ended up buying new bits for each job, but not any more. Quote Link to comment Share on other sites More sharing options...
Phil Hancock Posted February 17, 2012 Share Posted February 17, 2012 Would it be this that you are thinking of. http://www.drapertools.com/b2c/b2citmdsp.pgm?pp_skmno=44351 I have a very elderly Picador version and it worked very well, although i can free hand sharpen twist drills so i did not need to use it every time but just occasionally to true the edges up. Quote Link to comment Share on other sites More sharing options...
bushwhacker Posted February 17, 2012 Share Posted February 17, 2012 Yes thats the boyo, it works really well for just a small piece of equipment and £20 on everyones favourite buy stuff place. I need to get my youngest to show me how to do them linky things. Quote Link to comment Share on other sites More sharing options...
fatbloke Posted February 17, 2012 Share Posted February 17, 2012 When I was an apprentice one of the first things we made was a drill bit angle gauge. Then we spent a whole week grinding drills..........Oh what fun. You can buy the little angle gauges and with a bit of practice grind drills very well. Then I was taught to grind "fish tail" drills, bit like the spot weld drills which are brilliant for sheet metal as a normal drill can make a triangular hole in thin sheet. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.