Drill bits for forged and billet 6061 and or 7075 aluminum
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    Default Drill bits for forged and billet 6061 and or 7075 aluminum

    I have recently been doing some gunsmithing and building from 80% aluminum receivers.
    They are either forged or billet 7075 or 6061 receivers and looking for some recommendations on drill bits that work the best in this type of material.
    TiN coated bits were recommended buy a few folks but wanted to get some input on what others have used to drill clean holes in aluminum.
    Any info would be greatly appreciated.

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    Bright finish HSS. Sharp and fast

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    What I do on 80% receivers is to drill a bit under-sized holes (never trust a drill bit to make a round hole or be "accurate") and follow with the proper size reamer. Brand of bit doesn't make much difference this way as long as it's reasonably straight. IMO it's the best way to get good results.

    FWIW

    -Ron

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    Parabolic flute if you're going deep say over 4 xD


    Just my 2 cents YMMV

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    I like TiN coated stub drills on steel, but they suck when drilling aluminium on my small CNC, the swarf seems to bind to them more readily. So I'll echo the recommendation for bright or steam tempered.

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    NIST has published material sheets that describe various metals and how they are best machined. The one for aluminum is here: https://materialsdata.nist.gov/bitst...=3&isAllowed=y

    When drilling a material, to get the best possible result you should determine the optimum rake and relief angles for the material and feeds you are using. Insight into these two angles can be gathered from the aforementioned material reports.

    Once you know the angles, take standard HSS metal cutting drill bit and grind the rake and relief into the tip of the drill bit. You will then have an optimum tool for your drilling operation.

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    If you are drilling through a steel or annodized guide it will be hard on the drill tips causing burrs on exit especially given the quality of the average drill press these days

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    is this aircraft billet or military grade billet?

    Use a three flute Super Twister. That is the BEST

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    Yup. Military grade billet is really tough and yells Go! Go! Go! a lot.

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    I agree bright finish is what you want. Coatings tend to pick up aluminum.

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    Amazing and good information from all of you and really gives me a different perspective on just what drill bits to use. Most of jigs for these receivers use drill guides so I had never toyed with the idea of drilling undersized and reaming to correct size.

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    We sell these Nucon HSS drills. Lots of great feedback. Very affordable as well. We also have them in ZRN coating.

    Tool Holders, Collets and Machine Accessories NUCON Drills - MariTool

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    Quote Originally Posted by Spruewell View Post
    Bright finish HSS. Sharp and fast
    This, there is no need to spend money on fancy drills working in 6061 or 7075 unless you have an excessive depth to diameter ratio. Unless of course you are trying to machine crappy Chinese 6061, then all bets are off.

    P.S. Refrain from buzz words like billet. I can't believe it took till post #8 for a comment.

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    Gunsmithing, Aircraft piloting. Horse riding. Video game playing. Drinking, especially in nightclubs. Mainlining heroin. All activities in which I'm dead thankful I never took an interest.

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    Quote Originally Posted by GregSY View Post
    Gunsmithing, Aircraft piloting. Horse riding. Video game playing. Drinking, especially in nightclubs. Mainlining heroin. All activities in which I'm dead thankful I never took an interest.
    Horse riding isn't bad, it just isn't as easy as the experts make it look.

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    Quote Originally Posted by Dualkit View Post
    This, there is no need to spend money on fancy drills working in 6061 or 7075 unless you have an excessive depth to diameter ratio. Unless of course you are trying to machine crappy Chinese 6061, then all bets are off.

    P.S. Refrain from buzz words like billet. I can't believe it took till post #8 for a comment.
    ×3 on this, with an addendum. Don't spend money on fancy drills unless you have a high quantity of parts to do. It's not worth it. The benefit is small and it takes a lot of parts to add up to anything relevant in terms of the time spent. A plain bright drill or even black oxided drill will work just fine for one or two parts.

    I've just been working on about 6 or 7 of these 80% lowers for a friend of a friend, using plain old black oxide drills. No problems whatsoever. Absolutely do use a reamer for things like the pin holes, and WD40 for cutting oil works great.

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    Lookmif it's a forged billet part he needs to use a forged, billet drill. Buncha novices....

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    Quote Originally Posted by jim rozen View Post
    Lookmif it's a forged billet part he needs to use a forged, billet drill. Buncha novices....
    Just purchased the forged, billet drill. Thanks for moving me out of novice territory and into the RozenZone ; )

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    Quote Originally Posted by fmari --MariTool- View Post
    We sell these Nucon HSS drills. Lots of great feedback. Very affordable as well. We also have them in ZRN coating.

    Tool Holders, Collets and Machine Accessories NUCON Drills - MariTool
    And made in the USA I see, ..big

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    Quote Originally Posted by GregSY View Post
    Gunsmithing, Aircraft piloting. Horse riding. Video game playing. Drinking, especially in nightclubs. Mainlining heroin. All activities in which I'm dead thankful I never took an interest.
    I think Oscar Wilde said "I'll try anything once except folk dancing and incest."


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