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Thread: W point drills

  1. #1
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    Default W point drills

    Sort of wood/ sort of metal related -

    Previously to join planks of wood together I used a biscuit jointer but that technology is back in Adelaide, so I'm having to resort to wooden dowels. The drill bits I have here are 'normal' 118 degree pointed bits and without a centre punch can wander (and who centre punches wood?).

    Ideally a W point drill would be used (also known as a brad point drill, woodworker's drill and several other names). These have a central spike and a couple of wings so the outside of the hole is cut before the material in the middle is removed. These are also apparently used for sheet metal - the point geometry means that the sheet material is less likely to pull itself up the drill.

    I tried buying the ready made item from Bunnings, but they came in a set of 8 for $8, were out of carbon steel, wobbled like crazy and were in the bin after 2 holes. A sheet metal worker I once worked with taught me how to produce them off hand though, so tonight I tried it.
    Start with a normal drill bit like this -
    P1020014.JPG
    The grinding wheel you use must have a sharp corner on it. By holding it so that the tip and the outside of the flute are untouched, the W shape can be produced. The grinder I have here has not seen a dresser for many years but you can get the idea.
    P1020018.JPG
    The result is something like this
    P1020015.JPG
    In hindsight looking at the photo I could have gone a little further out towards the edge but it's a 6mm drill, so I might need some better magnification to get really close.

    Don would use these for drilling through thin sheet metal but I found that drilling into moderately hard hardwood they are fine (certainly better than the Supercraft carbon steel drill...)

    Michael

  2. #2
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    Good post Michael,

    Hopefully, some of our numbers will be encouraged to try this one. It is a fairly easy task, once you get the geometry sorted in your head.

    Indeed, the same grind, cuts shim metal with no burrs, given you use that timber support underneath.

    Once you can grind that drill, hand sharpening the jobber drills will be a piece of cake.

    Grahame

  3. #3
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    G'Day All,
    Thought that I would add a little to the "sheet metal drill" discussion.
    For sheet metal I have found that grinding the drill to points on the extremities of the drill flutes cuts a very round & true to size hole in sheet metals. Provided that, the web of the drill is 1 to 2 mm proud of the cutting points & that the hole is drilled at a very low spindle speed. Cutting oil also helps. The drill (25/32") below has had the web width reduced to a point to locate in a centre punch mark as the unreduced web is far too wide & the drill will wander uncontrollably.
    Regards,
    Don.

    DSCF4731.jpg

  4. #4
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    G'Day All,
    I do not know if this has been shown previously, apologies if it has!
    Further to the previous posts, I have made a short video of a modified standard twist drill for use on sheet metal. As mentioned, the web needs be proud of the two cutting edges to stop the drill wandering. Only the web point & the two cutting edges are cutting the material. Note the disk of material removed from the hole. As with any drill the web must be ground in the centre of the drill bit to cut an accurate diameter. Drill spindle is set at the lowest speed & a wipe over of straight cutting oil used.
    Regards,
    Don.


  5. #5
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    You know, the most annoying thing about discovering that there are special grinds for particular applications is that you want more drill sets
    • Set of Jobber drills
    • Set of stub drills
    • Set of drills set up for brass
    • Set of W point drills
    • Set of drills with flat ends (for drilling counter bores once the hole is started with a normal drill)


    Then, multiply that by 2 because you need both metric and imperial.

    Michael

  6. #6
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    Micheal
    Funny that you should mention drills in that context.

    This weekend the plan is to collect the drill bits from all over the shop and clean them up, resharpen them into sets for
    steel,
    brass and plastic
    timber

    I estimate I have a couple of kilos of drills just because of my poor habit of not always returning the drill bit to its index.They had become scattered all over the shed.

    It is a New Year resolution to create indexes / sets for all my types of drills.

    I am half way there having :
    a Metric to 13mm Cobalt set. A small set to 6mm Cat
    2 x complete Metric HSS sets to 13mm, in as one for the lathe and one for the D/Press,
    A nearly complete set of Imperial drills to 1/2" Sutton
    1 set Irwin spade bits- nothing fancy
    A boxed set of Forstener bits- Asian .

    It will be nice to find a nice sharp specific size drill immediately without having to hunt for it.

    Grahame

  7. #7
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    Quote Originally Posted by Don@2480 View Post
    Further to the previous posts, I have made a short video of a modified standard twist drill for use on sheet metal. As mentioned, the web needs be proud of the two cutting edges to stop the drill wandering. Only the web point & the two cutting edges are cutting the material. Note the disk of material removed from the hole. As with any drill the web must be ground in the centre of the drill bit to cut an accurate diameter. Drill spindle is set at the lowest speed & a wipe over of straight cutting oil used.
    Regards,
    Don.
    Hi Don,
    You hit the nail squarely on the head.The trick, of course, being to grind the drill center guide just a tad lower than the wings.

    The winged edges cut through first and there is no danger of the drill biting in.

    Thumbs Up Don

  8. #8
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    May 2015
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    Richmond
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    Found these sheets which look like they may be helpful. Best to use a 60 grit wheel to hold a 30 deg bevel (gives 60 deg inc on Zero Angle and Sheet metal points).

    Zero Angle (Other names also used for this point!) great for stitch drilling using overlapping holes. No runoff into adjacent hole. Also reduces load for harder/tougher materials.
    Attached Images Attached Images

  9. #9
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    I've had a set for at least 20 years. Also got another set ground up as flat bottom. You can never have too many drills. I've also got an assortment of "shorties" for when you need to get into confined spaces with an angle head attachment.

    Funnily enough, these were not something we were taught about when I was an apprentice.

    peter

  10. #10
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    Quote Originally Posted by OldRustyToolie View Post
    Found these sheets which look like they may be helpful. Best to use a 60 grit wheel to hold a 30 deg bevel (gives 60 deg inc on Zero Angle and Sheet metal points).

    Zero Angle (Other names also used for this point!) great for stitch drilling using overlapping holes. No runoff into adjacent hole. Also reduces load for harder/tougher materials.
    Was wondering when someone would say that the chisel point left would be a problem locating in a prick/centre punch mark. The full grind process of a Zero Angle drill point and Sheet Metal drill point is to rotate the cutting lip to around 45 deg from initial lip grind so that a secondary land is ground to the centre CARFULLY to create a proper point to locate in punch mark if needed.
    Attached Images Attached Images

  11. #11
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    What is it with drill bits all of a sudden, a mate just dropped of about 15 with a please sharpen note! ( don't ever tell people you can sharpen drill bits )

  12. #12
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    Richmond
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    Old China! Make the person who owns the drills stand there with you while you sharpen them. Although 15 drills should only have them in your hair for 15 minutes! Second thoughts, in this weather get him to bring a couple of 6 packs and extend the session to a couple of hours AFTER you sharpen the drills.

  13. #13
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    The problem of drilling or enlarging holes in sheet metal can often be solved by using a small pad of heavy cloth (at least four layers) This prevents the drill chattering and producing that ubiquitous three lobe hole! It also works when you have to enlarge an hole in solid metal and you want a clean sharp edge.
    Graeme

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