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Technical Shop Class Basics: How to Properly Drill a Hole in Metal

Discussion in 'The Hokey Ass Message Board' started by phartman, May 13, 2019.

  1. What is the smallest drill that the Drill Doctor will reasonably sharpen? What is your experience (as opposed to what the company advertises)?

    And all those odd leftover sets and odds-and-end bits I have in my shop from who-knows-how-long-ago, are they worth trying to sharpen? Or just start over fresh here? Maybe the leftovers can provide good practice material?

    And I saw an ad for a spring-loaded centering punch tool. Worth the money? Or just use the traditional punch granddaddy gave me and whack it with a ball peen hammer the old fashioned way?
     
    Boneyard51 likes this.
  2. 19Fordy
    Joined: May 17, 2003
    Posts: 6,307

    19Fordy
    Member

    Spring loaded center punches are very convenient and easy to use.
    Old drill bits are worth saving if they still have a usable length and the shank is not damaged to the point where it's not concentric with the body of the drill bit or cannot be held in a chuck.
    High quality drill bits are expensive so it's worth the effort to save and sharpen them especially if they are
    over 1/4" dia. Fraction sizes or Number and Letter size drills which are not commonly available.
    If it's a left hand twist drill sharpen it, label it and keep it.
     
    olscrounger likes this.
  3. fordrodsteven
    Joined: Apr 1, 2017
    Posts: 96

    fordrodsteven
    Member

    I can't say that I know about the drill doctor tooling. I learned how to sharpen by hand on a grinding wheel.
    I would sharpen any drill bits that I have because i's like throwing money away for a tool that may have plenty of life left in it. And yes you can keep working to improve your sharpening skills on those old drill bits.
    Again, why spend money if you already have the ball peen and center punch? You can probably spend your money on other things that are more desirable for you.
     
  4. alchemy
    Joined: Sep 27, 2002
    Posts: 13,850

    alchemy
    Member

    A decade ago I bought about 20 pounds of used drill bits for a couple bucks. I'd sit down at the Drill Dr. for an hour and sharpen a bunch til I got bored. That would last me a couple years. I've given a bunch to my brothers and Dad too. The only reason I throw away a drill bit is if it's bent.

    I can't say I've ever sharpened a bit smaller than 1/8" and had real good luck with it though.
     
  5. DDDenny
    Joined: Feb 6, 2015
    Posts: 11,651

    DDDenny
    Member
    from oregon

    Great points here.^^^^^
    Forty years ago my machine tech. instructor said "you can't move a punch mark", well I've been trying for forty years to prove him wrong, he's mostly right but if you flatten it and hit it enough times you can.
    It wasn't until my eyes went to hell that I put much value in those automatic center punches but they are looking pretty handy right about now.
     
  6. H380
    Joined: Sep 20, 2015
    Posts: 390

    H380
    Member
    from Louisiana

    1st is to understand the geometry of the point. You can't sharpen a bit without knowing and understanding it. 2nd when drilling a pilot hole the starting bit should be the thickness of the web of the finial size bit. Also you need a grinding gauge to get good points.

    472011-1.jpg

    4-11_drill_bit_geometry.jpg Drill-bit-geometry-a-twist-drill-bit-and-b-drill-bit-tip-11.png
     
    continentaljohn likes this.
  7. Ziggster
    Joined: Aug 27, 2018
    Posts: 213

    Ziggster
    Member

    Always clamp what it is your drilling or this can happen...
    image.jpeg
     
    clem, continentaljohn and wicarnut like this.
  8. Fortunateson
    Joined: Apr 30, 2012
    Posts: 2,173

    Fortunateson
    Member

    Good point and evidence to back it up! Your name isn't Frank N. Stein by any chance?
     
  9. 19Fordy
    Joined: May 17, 2003
    Posts: 6,307

    19Fordy
    Member

    Just one more point. Avoid buying those drill bit sets where the shank is
    1/4 in. and the drill bits are 3/8's and up. Total waste of money. Buy a 1/2 in. chuck drill that will hold a 1/2" drill shank.
     
    brad2v likes this.
  10. ??? What is the thickness of the web of the bit??? The center part of the bit, the thickness of the material there between the flutes? Just hold up the intended pilot bit and compare to the very center thickness of the final size bit? I think that's what you are getting at.

    Interesting. I never knew. Learning quite a bit here.
     
  11. Love this idea. I see those boxes of bits at yard sales and flea markets. Great suggestion. Thanks!
     
  12. 19Fordy
    Joined: May 17, 2003
    Posts: 6,307

    19Fordy
    Member

    This shows the web. It does no cutting.
    https://www.google.com/search?q=wha...rome..69i57.8079j1j4&sourceid=chrome&ie=UTF-8

    You are correct in your assumption about selection of the pilot drill in relation to the size of the web. However, it's always best to drill a pilot smaller in dia. than the web when drilling larger holes over 1/4 in. to increase accuracy.
    I even drill a pilot hole for smaller drill bits if I want the most accuracy and ease of cutting with a hand drill.
     
  13. 19Fordy
    Joined: May 17, 2003
    Posts: 6,307

    19Fordy
    Member

    So true.. I used to secure the chuck key to the head stock with a length of chain just long enough to reach the chuck. That way, if a student ever forgot,they wouldn't get hit with a flying chuck key. Thank goodness, it only happened once in all those years with all the students.
     
    X-cpe and brad2v like this.
  14. wicarnut
    Joined: Oct 29, 2009
    Posts: 2,990

    wicarnut
    Member

    SAFETY FIRST !!! ALWAYS securely block or clamp material down when using a drill press or mill. When drilling thin material use step drill or sheet metal bit, has center point and reverse angle. If you do not have either, use depth control on spindle because the drill bit will want to screw itself through. NEVER hold material in hand. Some coolant and slow spindle RPM is the way to go for a backyard guy. I hurt myself a few times being in a hurry when I first got into trade, 50 years, Tool & Die Maker and had my shop for 36 years, way more to drilling holes than most think, BE SAFE !
     
  15. trollst
    Joined: Jan 27, 2012
    Posts: 1,424

    trollst
    Member

    Jeez, all these 40 years, I thought you just pushed harder on the drill press till it wore through......seriously, learning to sharpen bits is one of life's most valuable skills.
     
  16. A friend of mine gave me a neat snap punch years ago and I consider it a necessary tool to prevent the drill bit from walking across the surface of the metal whether it is aluminum or steel. HRP

    [​IMG]
     
    gimpyshotrods and VANDENPLAS like this.
  17. You are talking about Deming Drills. They have a purpose in this world.
     
  18. Am I the only one who is bothered when people refer to the chuck key as a chuck. Or the other one that gets me is calling a drill motor as a drill.
     
  19. I will admit that I have never mastered the art of sharpening drill bit's, I am a pro at taking a poor cutting bit and after making a attempt to sharpen it make it completely useless.

    I have a old friend that can sharpen any bit and I honestly believe he could do it blindfolded, with one hand behind his back and gripping it with his teeth, OK a slight exaggeration with the teeth but you get where I'm coming from.

    I can do many different things but this is one I still have trouble with to this day, I suppose I am the kind of guy they invented the Drill Doctor for. :rolleyes: HRP
     
    Last edited: May 15, 2019
    olscrounger likes this.
  20. Ah but, I have a reduced shank ( 1/2" ) set from 9/16" - 1" that help out immensely and always use a 1/2" collet with them. Smaller ones not so much...
     
  21. gatz
    Joined: Jun 2, 2011
    Posts: 1,356

    gatz
    Member

    An old trick that an "old" machinist (my boss) taught me;
    On a drill press, when stepping up or opening up an existing hole or even just getting to a 1" diameter from a smaller hole for instance, fold a paper shop towel in 4ths. Nylon scrim type works well.
    Although it would work, it's not recommended to try this with a cloth towel !
    Have the larger size drill eye-balled over the smaller hole.
    With the drill motor off, bring down the drill and capture the folded towel under it by exerting a little downward pressure. Helps to coat the towel with cutting oil first.
    Keeping the pressure on, turn the drill motor on and proceed to cut the hole. Let the drill do the work.

    This works especially well for taking out a small amount of material, will keep the drill from "walking" around avoiding that nasty, inadvertent out-of-round chamfer.
    Main thing is to keep the material from moving while drilling.
     
  22. continentaljohn
    Joined: Jul 24, 2002
    Posts: 4,129

    continentaljohn
    Member

    All very good points here Also Know the materials your cutting as well . It’s not only speed but its also cutting angle. For instance when cutting brass or bronze you put a flat on the cutting edge . This is taking the sharpness out a bit ,so it will not grab and pull the material up . When drilling a unspotted or punched surface I like to use a center drill.. a example would be on a lathe or mill but also can be used on a drill press . A punch would be the correct way on a drill press followed by center drill . image.jpg
     
    Bearcat_V8 likes this.
  23. Went to try and buy one of these last night on-line. The Amazon reviews for all of them that I found were less than stellar. Anybody have a recommendation? I don't care so much about the cost- just don't want to get it and have it not work, or fail after the first couple of times it is used. That seems to be the biggest two complaints. Open to suggestions here on brand.
     
  24. DDDenny
    Joined: Feb 6, 2015
    Posts: 11,651

    DDDenny
    Member
    from oregon

  25. DDDenny
    Joined: Feb 6, 2015
    Posts: 11,651

    DDDenny
    Member
    from oregon

  26. Pete1
    Joined: Aug 23, 2004
    Posts: 1,630

    Pete1
    Member
    from Wa.

    "??? What is the thickness of the web of the bit???"

    Little publicized or discussed. It varies. The web gets thicker as the drill gets shorter.
    It is a whole other science to properly narrow the web to keep the drilling pressure down
    and 2 clean chips coming off.
     
    Als27T likes this.
  27. DDDenny
    Joined: Feb 6, 2015
    Posts: 11,651

    DDDenny
    Member
    from oregon

    I was a machinist for thirty years, twelve of which were in the toolroom, hand sharpened thousands of drill bits as well as doing all the large drill bits on a machine.
    I never was good at thinning the web on small drill bits and I attribute that partly to eyesight issues but a big part was not having a dedicated grinder/wheel for that purpose.
    One guy in the shop was good at it so he did them when needed.
     
    Als27T likes this.
  28. How about people that call a key a keyway??
     
  29. Not to be confused with a New Zealander.
     
    delaware george, D-Russ and X-cpe like this.
  30. DDDenny
    Joined: Feb 6, 2015
    Posts: 11,651

    DDDenny
    Member
    from oregon

    The one that makes me go "cripes" is when someone says "just run a tap over the bolt to clean up the threads".:confused:
     
    Truckdoctor Andy likes this.

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