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Drill bit sharpening....Fact or fiction?

Discussion in 'The Hokey Ass Message Board' started by ROADRAT EDDIE, Oct 5, 2006.

    Joined: Apr 17, 2005
    Posts: 1,349

    from New york

    Nothing worse than spending $25.00 on a 3/4" bit, have it go dull, and not being able to sharpen it like when it was new.....Anybody have the secret?
  2. mpls|cafe|racer
    Joined: Jun 18, 2006
    Posts: 1,323


    Yeah, get a drill gauge and sharpen it on a belt sander. Proper sharpen angle should be 118 degrees, or 59 degrees per side.

    Practice on an older bit.

    I'll post a pic of my drill gauge I made in a minute.
  3. brokenspoke
    Joined: Jul 26, 2005
    Posts: 2,910


    Get a Drill doctor...
  4. It is kind of hard to explain.
    Use a fine grinding wheel.
    Grind the back edge of the bit against the side of the grinding wheel
    Be careful to not get the bit too hot or off center.
    The bit will probably never be as true as original, but it will still be functional.
    I have managed to salvage several bits in this manner.

  5. Hey, another Houstonian! Have you used one? I've heard mixed reviews on these...
  6. Kilroy
    Joined: Aug 2, 2001
    Posts: 3,225

    from Orange, Ca

    I've used it...

    It seems to work but the bit gets dull faster than a new bit...
  7. chopolds
    Joined: Oct 22, 2001
    Posts: 5,894

    from howell, nj
    1. Kustom Painters

    I, myself, an completely inept when trying to sharpen drill bits.
    Bought a Drill Doctor, and everything is great!
  8. Were they good bits to start with, or cheapies? I BENT some Northern tool bits. Actually several of them from the same box, on sheetmetal, no less! I've broken bits in the past, but never fuckin' BENT one till now.
  9. Flexicoker
    Joined: Apr 17, 2004
    Posts: 1,416


    Drill doctors are wonderful... get the diamond grit one and it will last a long time.

    Its not hard to sharpen bits by hand though... just use a sanding wheel and follow the contour thats already there.
  10. mpls|cafe|racer
    Joined: Jun 18, 2006
    Posts: 1,323



    Using a drill doctor for this is like paying someone to wipe your ass. lol

    If you're gonna be doing it often, might as well learn how to do it right so you don't get screwed when you have to try.
  11. buschandbusch
    Joined: Jan 11, 2006
    Posts: 1,279

    from Reno, NV

    never been able to get the Drill Doctor to work. Tried hundreds of times but it never got them right. Since then I just do it on a bench grinder freehand- it's best if you have your work shelf angled up correctly into the grinding wheel, with one of those bit sharpening attachments. Then you split the point by turning it over and grinding off the backside, hard to explain without pics. It takes pratcice on a grinder, but I haven't bought bits in years.
  12. REJ
    Joined: Mar 4, 2004
    Posts: 1,612

    from FLA

    I for one, can not do it right, so therefore I use a drill doctor.
    It works a hell of a lot better than when I try to sharpen one by hand. I always manage to get one side longer than the other if you know what I mean.
    Joined: Apr 17, 2005
    Posts: 1,349

    from New york

    Never heard of that........
  14. mpls|cafe|racer
    Joined: Jun 18, 2006
    Posts: 1,323


    Yeah I do know.... it means you don't use the right angles on the sander, and you overpressure the one side. Just takes some practice.

    I just think that stuff like this is basic tooling, and we should all know how to do it by hand, in case our handy dandy "do it for me" tools aren't available to us. :D
  15. marq
    Joined: Aug 22, 2003
    Posts: 1,423


    When i was doing my Apprenticeship my instructor told me never ever use the side of a grinding wheel.............they can and do explode.........Marq
  16. Petejoe
    Joined: Nov 27, 2002
    Posts: 10,807

    from Zoar, Ohio

    I bought one of those "drill doctors". reasonable and worth it.
  17. Appleseed
    Joined: Feb 21, 2005
    Posts: 1,053


    My old man swears by his. We were like " this thing'll work great, or we'll be screwed out of $60.00." His only regret was he didn't get the bigger one.
  18. That is the difference between a hobbyist(me) and a professional(you), I never considered that possibility. Looks like I will dress my grinding wheel straight across the face and go about it that way.
    Thanks, Chip.
  19. scottybaccus
    Joined: Mar 13, 2006
    Posts: 4,109


    Had a Drill Dr.
    Used it in a production shop for years, until it just fell apart. Probably sharpened 1000 bits with it. Havn't needed one much lately, but I'll pay for another when I do.
    Old guy that owns the shop swore up and down he could do just as well by hand. After a while, he used it more than the rest of us. Hmm.
  20. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,682

    Bruce Lancaster
    Member Emeritus

    The angle and the centering are only part of it--also, there's the relief: Thr flutes on each side have to be angled slightly away from the leading cutting edge...very hard to describe. They slant down away from that leading edge a very few degrees if you are looking down at the point... The big bits you can do by eye, the tiny ones require a kind of blind sweep and twist motion to get those reliefs done by pure zen voodoo since you'd have to be crazy to put your eye close enough to actually see what's happening there!
    And keep a cup of water by the grinder and dippit after each hit on the grinder--it's very easy to get local overheating and cook the metal at the point.
  21. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,682

    Bruce Lancaster
    Member Emeritus

    Some pics:

    The normal angle is kinda a general purpose choice; if you look in books like old Machinery's Handbook, there are different tip angles for different metals. Cast iron likes a different angle than steel. Some results are very strange--a decent bit that will drill steel perfectly well sometimes won't even touch crappy diecast stuff--I remember being unable to get a good bit started into the potmetal stuff in a broken Chevy window handle knob, metal I probably could have sliced away with my pocketknife. I finally gave up, turned the bit backwards, and ground a primitive 19th century looking V tip flat point into the shank, and buzzed right through...
    My own biggest drilling bugaboo: leaving the damn drill motor in reverse--by the time I realize that I'm going nowhere, I have polished the edge right off of the bit.
  22. bobw
    Joined: Mar 24, 2006
    Posts: 2,368


    When they get dull I just push harder. Actually, I just replace the small ones and dress the large ones on a grinding wheel. I always drill a small pilot hole and use progressively larger bits til I arrive at the desired hole size. The large ones seem to stay sharp a long time that way.
  23. I almost always use some type of lube when cutting or drilling...I've even used Pam (the cooking spray, not the girl) in a pinch!
  24. plan9
    Joined: Jun 3, 2003
    Posts: 4,045


    drill doctor is $60.00 at Sears, good tool to have around.
  25. REJ
    Joined: Mar 4, 2004
    Posts: 1,612

    from FLA

    Speaking of oil on bits, has anyone tried Gibbs in this application?
  26. mustangsix
    Joined: Mar 7, 2005
    Posts: 1,297


    Drill Doctor. Got one two years ago. So much fun to use I sharpened all my stuff, my neighbor's stuff.....this thing has saved me tons of time and aggravation. Yeah, you can sharpen bits by hand, but believe me, this is fast and effortless.
  27. Brad54
    Joined: Apr 15, 2004
    Posts: 6,015

    from Atl Ga

    Yup, got a Drill Dr. too. Love it, and wouldn't be without it.
    There are two different tip angles: one for wood, one for steel. (Don't remember which is which).
    My drill doctor also has a setting that can split the point, so it doesn't walk or skate off the mark.
    Center punch all your holes, and drill slow. "High Speed Steel" does NOT mean you use the drill at the fastest possible speed you can spin it! (I actually had an idiot I worked with tell me that one time. "Well if you're not supposed to spin them fast, why do they call it High Speed Steel?!" Never argue with someone who says that.)
    Starting with high quality drill bits will help the new points last longer, but even if they go dull quicker than the factory point, you've got a drill doctor, so just resharpen it? I don't throw pencils away just because I have to keep sharpening them, and I don't dislike my electric pencil sharpener because it does the job quicker and eats more material.
  28. Digger_Dave
    Joined: Apr 10, 2001
    Posts: 2,517


    Ah ha, so I'm not the ONLY one who does that!! :D

    I bought a drill doc several years ago ... but still, (even after watching the included video tape 88 times!! ) I just can't seem to get a good point on my dull drill bits.
    Solved the problem for all sizes up to 7/16ths ... buy NEW ones in BULK!! :D :D
  29. flatheadmalc
    Joined: Mar 4, 2006
    Posts: 245


    Got a Drill Dr. think it's great, dull bits go into a can until i have several then it's sharpening time!
  30. Vance
    Joined: Jan 3, 2005
    Posts: 2,135

    from N/A

    I used to work at a machine shop and we had what looked like a Drill Doctor on steriods. This thing was huge and the wheel was like $160 to replace.

    When I first started working there, one of my jobs was to take a big box of old bits and sharpen them. Man, there musta been like 300 bits in there. After I cleaned up them, I brought all mine in and dressed them. I miss that beast. Made me decide to buy a Drill Doctor and get the big one to boot.


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