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  1. #1
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    Default Boring Bar Question

    What is preferred for a small diameter solid carbide boring bar that has some reach to it? I see various models by Kyocera but there are so many choices that my head starts swimming. They all seem short, 1/2Ē or something. I tried to grind my own and I unsurprisingly snapped it off.

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    I make a lot out of old endmills.

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    Minimum bore diameter will be your guiding factor, so how small you wanna go?

    I've had good luck with Maritool's solid carbide insert-type bars. They start at 1/4" OD with .31" min ID. SOLID CARBIDE BORING BAR .250 MariTool

    If that's not small enough, preground from Micro100 would be my next choice. https://p.widencdn.net/3dj8ro/Micro100_FullCatalog 6xD seems to be about the limit of their preground units, but they get as small as 0.050" min bore with .400" DOC.

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    Default Boring Bar Question

    Quote Originally Posted by Cole2534 View Post
    Minimum bore diameter will be your guiding factor, so how small you wanna go?

    I've had good luck with Maritool's solid carbide insert-type bars. They start at 1/4" OD with .31" min ID. SOLID CARBIDE BORING BAR .250 MariTool

    If that's not small enough, preground from Micro100 would be my next choice. https://p.widencdn.net/3dj8ro/Micro100_FullCatalog 6xD seems to be about the limit of their preground units, but they get as small as 0.050" min bore with .400" DOC.
    Excellent, very helpful. Thank you.

    Iím not knowledgeable about insert tooling. Iíve got a few I seem to get along with but just out of sheer luck.

    If a guy was looking at boring barrel steel material or similar, what would be a good insert? I have a manual lathe and Iím limited to about 800 rpm. Past that and it throws the beltBoring Bar Question. Iím working on a sight project for a model 92 clone and I donít like whatís available commercially.

    Thanks again for the guidance.

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    Quote Originally Posted by gbflyer View Post

    If a guy was looking at boring barrel steel material or similar, what would be a good insert?
    Still boils down to how small you wanna go. You boring pilot holes for #0-80 screws or rechambering a Mk45 deck gun?

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    For really small holes forget using inserts.

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    Anything under 1/4" dia I most of the time go with solid carbide. Much stronger.

    Solid Carbide TiN Boring Bars - MariTool

    Solid Carbide Multi Extension Boring Bars - Made in USA - MariTool

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    Quote Originally Posted by Cole2534 View Post
    Still boils down to how small you wanna go. You boring pilot holes for #0-80 screws or rechambering a Mk45 deck gun?
    I would like to be able to get small enough for a 8-40 screw for one application. .250 for another.

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    Why do you want to use a boring bar in this instance? Tiny holes mean tiny reaches. I would use a drill ( and ream if that much precision is needed.) A gun drill would probably be best (but not cheap) if the hole is really deep.

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    Mostly just the challenge. Hobby guy not in production setting.

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    boring bars have a stickout length to diameter ratio
    .
    obviously when you get much above 5 you start have deflection issues
    .
    1" dia thats 5" stickout
    0.1" dia thats 0.5" stickout
    .
    when you 2x stickout length deflection is 2x2x2 or 8x more
    when you 3x stickout length its 3x3x3 or 27x more deflection
    .
    its one of those laws of the universe. it is what it is

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    Quote Originally Posted by fmari --MariTool- View Post
    Anything under 1/4" dia I most of the time go with solid carbide. Much stronger.

    Solid Carbide TiN Boring Bars - MariTool

    Solid Carbide Multi Extension Boring Bars - Made in USA - MariTool
    I'm not convinced it is a strength issue. I've used inserted bars down to 3/16". The problem I always had was the teeny tiny torx screw to mount the insert, drop it and it's gone!


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