Twist Drill Sharpening Helper

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Introduction: Twist Drill Sharpening Helper

About: I miss the days when magazines like Popular Mechanics had all sorts of DIY projects for making and repairing just about everything. I am enjoying posting things I have learned and done since I got my first ...

One day I discovered I could hand sharpen twist drills, even though I always thought I would never be able to do it. Still, it is helpful to have a guide to check the angle and to be certain the center of the drill is not off side. This Instructable will show how to make a simple, inexpensive low tech guide.

Materials

  • Stick of wood
  • Machine screw

Tools

  • Protractor
  • T bevel square
  • Drill with a brad point (drill) bit
  • Screwdriver

Step 1: 59 Degrees

Mark two straight lines on paper as shown at 59 degrees. General purpose twist drills use a 59 degree angle.

Step 2: Transfer and Mark the Angle

Use a T bevel square to transfer the 59 degree angle to a square piece of scrap wood. I am using a piece of hardwood from an old cabinet door. It is 5/8 inch thick. I will be using an 8-32 machine screw, so I selected a drill just a little smaller so the threads on the screw can catch in the wood as if it were a nut. A brad point bit is easier to start precisely when drilling at an angle. The drill is handheld, so I used my eyesight to align the drill with the 59 degree guide line as best as possible.

Step 3: Insert a Screw and Check

I inserted an 8-32 machine screw through the piece of wood. I doubt I will ever sharpen a drill larger than 5/8 inch. Select a screw long enough to come through the wood half the diameter of the largest drill you expect to sharpen.

If the angle of the screw is not close to the guide line, drill another hole and try again. (The line and the screw appear poorly aligned in the photo. But, I stood directly over both and placed a straightedge on the line. It and the screw are quite well aligned, despite how the photo appears.)

Step 4: Using the Guide

The threads on the screw are close enough together to use as a straight line to check the grinding angle.

Turn the screw so something fine, whether the end of the screw or one of the threads aligns with the web at the center of the drill. As you grind the twist drill to sharpen it, turn the drill one half turn to see if the web aligns with the marking point you chose on the screw. If the web does not align with the mark you set, grind a little on the short side to lengthen it and to bring the web into the center of the drill.

Step 5: Grinding

Here is a good video on sharpening a twist drill by hand. It is less than twelve minutes.

The photo provides an overview of the video. Begin by grinding the area on both sides shown in red. Raise the angle of the bit and grind the area shown in yellow. Finally, grind in a continuous motion beginning at the point farthest from the cutting edge and make a smooth grind that comes near to the cutting edge as defined by the blue lines. The video suggests grinding on the sides of the web to shorten or thin it some.

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    28 Comments

    Two help full hints learned a long time ago.

    When using two nuts. set them up by using a new factory ground drill.

    we soldered them to a 2 inch wide piece of 1/8 " Today one may use epoxy.

    Now the secret is to get the required flats into perfect alignment

    Then when epoxy is hard lay in the new drill again but this time mark the centre of the shank on the flat. One can then scribe a line down the flat bar as a centre line for any drill . Don't eye the point you are grinding. Grind for contact to keep the shank on the center line. this centers the drill .

    The other trick albeit for larger drills is to have a 2 x 1/8 flat with a 90 degree bend at the bottom. Through this drill and tap two bolts one with a cup the other with a point. Grind one face of the drill; set the shank on the right bolt and scribe a line on the steel. Use marking blue or chalk. Now grind the other cutting edge face to match.

    Interesting idea... or maybe just hold two nuts together to get the 120 degrees?

    120.jpg
    2 replies

    Someone else suggested that. Yes, the space below the nuts is 120 degrees wide and that is very close to the 118 degrees suggested as the standard. But, how do you make certain the 120 degree angle is centered or equally divided on both sides of the drill's center line? The guide I detailed shows you each face is 59 degrees from the center line of the drill. Two nuts show you only that both faces are 120 degrees apart.

    118 degrees is only for one particular material. Drilling wood, for example, one would cut a different drill point, say 90-100 degrees... drilling inconel otoh would require a geometry nearer 130-135 degrees. Tying yourself down to some vague 118 degree point geometry is actually missing the point.

    Are the commercially available drill bit sharpeners effective? I have a mechanic friend who claims they are not.

    5 replies

    First, great instructable!

    I've had a Drill Dr for many years and like it very much. It allows you to choose from a couple grind angles and it puts the relief on the back of the cutting edge as pointed out by jgaudreault. I've gotten very consistently good results. Occasionally I've struggled with small bits (less than 3/32). Sometimes I don't get the small bit in quite right and have to regrind it to center the point, but it's still very fast. Mine stays on the bench all the time. It's so quick I don't hesitate to touch up a bit if I have any concern about its sharpness.

    Drill on!

    My son-in-law has a smaller Drill Doctor. I used it successfully once, but got poor results another time. The very fine grit indicated to me it is a good machine for a light touch up, but very slow if substantial grinding is needed to restore the drill's profile.

    In my (limited) experience with a Drill Doctor, they can be very effective, but they aren't as easy to use as you would think. If you don't follow the instructions to the letter, (and iirc there are some counterintuitive things in the instructions,) you will not have good results. I think the DD should be good for sharpening a bunch of bits at once, because if you've got a bunch, you can afford to sit down and re-read the instructions and do it right. DD regrinds split points as well.

    I think if I only had 1/4" and larger drills to sharpen I'd do it by hand. A jig of some sort is more critical on the smaller bits.

    I purchased a Drill Doctor years ago thinking it would be quick and easy but found it worthless (MY EXPERIENCE) ended up redoing all the bits by hand after using the DD. For me it was a waste of money and time. It does however give me a proper center as a starting point for broken bits.

    I used to work in a machine shop. Tool crib manager used to hand sharpen all our twist drill bits by eye. They were like new. I used to sharpen all my own bits with the fine grinding wheel on my grinder. Got pretty good at it. As far as the $100+ bit grinders, I've never used one. I think the guide designed here along with a grinder would save anyone a lot of money.

    I think this is what instructables are all about. It's simple, it's effective, it's cheap and it will get used over and over and over. (In my shop anyway!) Thanks Phil.

    1 reply

    Thanks.

    For softer metals a sharper angle can be used . Put anither scew on the other end for aluminium. Good tool!

    3 replies

    Thank you for the suggestion.

    A friend bought one of those drill sharpeners (after I told him not to waste his money) and some dead bits around for me to sharpen as he had no clue how to go about it. I could sharpen 10 by eye on my bench grinder in the time it took me to set up and grind / regrind/ regrind 1 on the useless sharpener.

    This jig you have shown is nifty in the way you can see an off-centre grind.

    I have used a scribed line at 59 degrees on the work rest of the bench grinder, just fill it with white chalk every now and then.

    thank you for looking. A magnifying glass might be helpful when checking the grinding for a centered web.

    https://www.instructables.com/id/Sharpen-Your-Drill-Bits/

    A few years ago I did an Instructable on sharpening drill bits using a jig once sold by Sears and still available many places. It worked quite well, if set up properly and tweaked during use. I tried to include some hints I learned by experience. For bits smaller than 3/16 inch a speciallycut wood block and an oil stone works quite well. You should be able to search for that Instructable and find it. I am on an iPhone and there are limitations.

    In H.S. Metal Shop class when I learned to hand sharpen drill bits (and lathe bits) I had commercial gauges stamped from sheet steel for the correct angles necessary for cutting the appropriate materials. Grind and insert in gauge, rinse repeat until correct. Essential for threading on a lathe. Anymore I just eyeball it having sharpened thousands of drill bits over the years since.

    I have been trying to do this for years on and off. Thank you for a demonstration that uses the correct words, concepts and explains them well ! I wasn't far off, but I made too difficult by trying to continually cut back the relief. Addressing the web flat helps from drill skating also.