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Thread: fuller bit for brass

  1. #1
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    Default fuller bit for brass

    i'm about to install a brass strip on a keel bottom. do you need a special fuller bit to countersink a hole in brass?

    thanks

    David

  2. #2
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    Default Re: fuller bit for brass

    i would drill the holes for screw shank diameter first and then use something like this


  3. #3
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    Default Re: fuller bit for brass

    Quote Originally Posted by coelcanth View Post
    i would drill the holes for screw shank diameter first and then use something like this ...
    The technical name is a countersink, they come in different angles so make sure to ask for the one you need, places like McMaster-Carr carry them, or your local machine shop supplier.

    But I hate the ones you pictured. They chatter way too easy. The single-flute version works better.

  4. #4
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    Default Re: fuller bit for brass

    Yes, the Ford Uniflute countersinks are available from most of the big supply houses like Manhattan Supply, Grainger, or McMaster-Carr.

  5. #5
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    Default Re: fuller bit for brass

    +1 on single flute countersinks. Make sure the angle matches the screws,
    Everything changes . Everything is connected . Pay attention

  6. #6
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    Default Re: fuller bit for brass

    I just use a high carbon bit that's the same diameter as the screw head. Sometimes I need to change the angle to the point a little.

  7. #7
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    Default Re: fuller bit for brass

    ^ Real countersinks do not grab and pull in just at the wrong moment...when depth is critical, for example when matching screw head depths, a real countersink has the accuracy needed. I find using drill bits ok for some jobs, but not when it absolutely must be accurate.

  8. #8
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    Default Re: fuller bit for brass

    Quote Originally Posted by Ian McColgin View Post
    I just use a high carbon bit that's the same diameter as the screw head. Sometimes I need to change the angle to the point a little.
    Like this? https://youtu.be/pAngKHIZgyA
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  9. #9
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    Default Re: fuller bit for brass

    A countersink like this is the best:
    https://littlemachineshop.com/produc...ProductID=4542

    Before using, a hole must be drilled with a jobbers type bit, but is best if dubbed for brass.

    Jeff

  10. #10
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    Default Re: fuller bit for brass

    MN Dave, neat and more sophisticated than my own learn by breaking approach. Since I'm not drilling through, but rather am making a countersink, I grind the tip angle to match the screw and set the screw on the drill press for firm stop.

    I erred in my first remarks. I use an old bit that's a bit larger than the screw head controlling the depth of the countersink by the drill press stop. The messy tear-through that can happen with soft metals happens when the full width of the drill is engaged.

  11. #11
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    Default Re: fuller bit for brass

    Quote Originally Posted by jpatrick View Post
    A countersink like this is the best: ...
    Those are nice but I wouldn't say "best". Different materials, different uses, different styles work better or worser. The single-flute is the most versatile (except maybe for the hack job of using a regular drill bit, ahem. And I'm a cheapskate but the FIRST principle of metalworking is short = rigid, rigid = works best. A big-ass long thing with half the metal removed does not do the best job.)

    You can use a single-flute sink in wood, too, which might be nice for woodboat people. It's worth the ten bucks.

  12. #12
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    Default Re: fuller bit for brass

    Drilling more than a couple holes? I had to drill and countersink a BUNCH in 1/2” brass 1/2 oval rub rail. This is the go to tool. Set it in a drill press with a vice holding the brass. You’ll get very consistent depth, professional results.

    https://www.northerntool.com/shop/to...1725_200451725
    Fight Entropy, build a wooden boat!

  13. #13
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    Default Re: fuller bit for brass

    yes these are great especially if the speed is right, work well-supported and you use thread cutting oil or the like.
    Quote Originally Posted by Rob Hazard View Post
    Yes, the Ford Uniflute countersinks are available from most of the big supply houses like Manhattan Supply, Grainger, or McMaster-Carr.

  14. #14
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    Default Re: fuller bit for brass

    i'm confused about angles. from what I can tell is that countersinks for metal have a different point angle than the wood screws that I'm going to use to attach the brass strip to the keel. ??

  15. #15
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    Default Re: fuller bit for brass

    I seem to recall I used 82 degree countersinks, but I wouldn't worry too much about a degree or two. My preference would be that the c'sink be a little "pointier" than the underside of the screw head, so the screw fetches up tight around its rim. This is metalworking, yes, but it's not "machining". You're just attaching rub strips to slide the boat over the gravel!

  16. #16
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    Default Re: fuller bit for brass

    All the wood screws I've used are 82 degrees. In metal working, most inch-sized machine screws in North America are 82 degrees, but 90 degree screws are also available. The default angle in metric machine screws seems to be 90 degrees. If you are planning to use a lot of flat head machine screws it is a good idea to have both an 82 and a 90 degree countersink. Using the wrong one makes for a really poor fit.

  17. #17
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    Default Re: fuller bit for brass

    Quote Originally Posted by dposner View Post
    i'm confused about angles. from what I can tell is that countersinks for metal have a different point angle than the wood screws that I'm going to use to attach the brass strip to the keel. ??
    The countersink and head should have the same angle. Most likely, the screw will have an angle between 80 and 82, so you need the same for the countersink.

    After years of dealing with fastener specs, I'm not surprised that you are confused. Fastener standards are like software user agreements. 20 pages of muck to say that you are screwed. I worked at a place that had a hallway filled with sample fasteners mounted on the wall. There were hundreds of them. The angle is hard to control perfectly, so the specification always has a 2 range.

    In the US, most flat head screws are governed by ASME B18.6.3 for machine screws and ASME B18.6.1 for wood screws. The flat head angle is normally 80-82. Most metric flat heads are 90 - 92 and governed by ANSI/ASME B18.3.5M in the US and and DIN standards like DIN 7991 in Europe. 100 flat heads are governed by aircraft standards such as FF-S-92, MS24693, NASM24693.

    Machine Screw, Flat Head, Cross Recessed, Zinc Plated (80-82)
    Dimensions: ASME B18.6.3
    https://www.fastenal.com/content/pro...s/MS.FPH.Z.pdf

    Wood Screw, Flat Countersunk Head, Cross Recessed, Brass (80-82)
    Dimensions: ASME B18.6.1
    https://www.fastenal.com/content/pro...WS.FPH.BRS.pdf

    Metric, Flat Head Socket Cap Screws, Class 10.9, Black Oxide
    Head angle is 90 +2/-0 degrees for sizes M3 through M20 and 60 +2/-0 degrees for sizes M22 and larger.
    Dimensions: DIN 7991
    https://www.fastenal.com/content/pro...CS.10.9.BO.pdf

    Metric, Flat Head Socket Cap Screws ANSI/ASME B18.3.5M (90-92)
    https://www.fastenersuperstore.com/p...ead-cap-screws

    Mil. Spec. Stainless Steel Phillips Flat Head Screws
    100 Degree Countersink Angle, 8-32 Thread, 5/8" Long
    Specifications Met Fed. Spec. FF-S-92, Fed. Spec. QQ-P-35, MS-24693-C51, NASM 24693
    https://www.mcmaster.com/93085a196
    Last edited by MN Dave; 06-07-2019 at 01:50 PM.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  18. #18
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    Default Re: fuller bit for brass

    If the boat is to be used in salt water, you might consider using bronze rather than brass both for the strip and screws. Brass and salt water have a short life span with the brass being the looser! It will rapidly corrode and disintegrate in a few years.
    Consider using bronze, even though it will be a bit more expensive than brass, the savings in having to do the same job a second time in a short while will justify the extra expense!
    Jay

  19. #19
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    Default Re: fuller bit for brass

    i have never been able to find bronze half round or half oval or even plain strip from any common supplier..
    do you have a good source for silicon bronze material that would be suitable for this purpose ??

  20. #20
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    Default Re: fuller bit for brass

    It used to be pretty easy to find. But advances in boat construction methods have now made it scarce are builders now seek places to save dollars. You need to start a search on line. Alaskan Copper and Brass would be a good place to start unless you can think of a bronze supply near you. Wishing you good luck with your project!
    Jay

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