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Thread: Building a 80%/90% M4 lower w/drillpress???

  1. #21
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    Quote Originally Posted by decodeddiesel View Post
    I understand the political appeal to "manufacturing" your "own" lower, but from a cost analysis, I don't see how you would save a penny without doing 10+ lowers due to the tooling cost of doing it right. Obviously folks who have a respectable hobby mill or better at home with the proper tooling are in a different boat, and I can see how it would appeal to them more as a fun machining project with tangible results. But to the guys trying to machine these on a $200 drill press, with little or most likely no machining experience, and a drill index as you only tooling, I think you're setting yourself up for disaster. I'm not even mentioning the measurement tools you would need to properly inspect your work and ensure you are adhering to the prints. If I were you, I really wouldn't trust an 80% done on a drill press for much more than a plinker.

    Evil thought: Give me a small CNC mill like a Tormach or whatever, a copy of EdgeCAM or Master CAM and I could crank out 3-5 of these a day once I got a good fixture setup.
    It has absolutely nothing to do with economics but I do agree about not doing it on a drill press. I have no plans on using anything but a mill, however, I have personally seen a few that did use a drill press. Aside from looking like complete ass, they functioned just fine.

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  2. #22
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    Quote Originally Posted by Ryno12 View Post
    It has absolutely nothing to do with economics but I do agree about not doing it on a drill press. I have no plans on using anything but a mill, however, I have personally seen a few that did use a drill press. Aside from looking like complete ass, they functioned just fine.

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    Quote Originally Posted by decodeddiesel View Post
    I understand the political appeal
    I get it, and I like the idea of 80% receivers a lot. I'm curious to hear some 1st hand feedback on folks who have done these successfully.

    I guess the OCD machinist/engineer in me has a hard time with half-assed drill-press/dremel jobs, but if it works for you then cheers!

  3. #23
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    I have built one with a 2/3 hp drill press and carbide end mills. final sanding with a dremel tool and sanding drums. I also used a cross slide vice on the press. It can be done. I have twice the cash in it than buying a stripped lower but the challenge was what pulled me in.

    I sold all the end mills and jigs to recover 1/3 of what they cost me.

    If I were to do another one, I would want a hobby mill machine to make it easier.
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  4. #24
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    Has anyone done one of the plastic 80% lowers? YouTube videos make it look easy enough.

  5. #25
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    Quote Originally Posted by decodeddiesel View Post
    I understand the political appeal to "manufacturing" your "own" lower, but from a cost analysis, I don't see how you would save a penny without doing 10+ lowers due to the tooling cost of doing it right. Obviously folks who have a respectable hobby mill or better at home with the proper tooling are in a different boat, and I can see how it would appeal to them more as a fun machining project with tangible results. But to the guys trying to machine these on a $200 drill press, with little or most likely no machining experience, and a drill index as you only tooling, I think you're setting yourself up for disaster. I'm not even mentioning the measurement tools you would need to properly inspect your work and ensure you are adhering to the prints. If I were you, I really wouldn't trust an 80% done on a drill press for much more than a plinker.

    Evil thought: Give me a small CNC mill like a Tormach or whatever, a copy of EdgeCAM or Master CAM and I could crank out 3-5 of these a day once I got a good fixture setup.
    To some, like me, who live in commie states, it's not about economics, it's about not having to file paperwork with the state agencies or feds. The climate in MD right now, like a handful of other leftist led states is just too risky for me to tell them what I have, so...

    Fortunately for me, I have access to a machine shop with non cnc setups (mills and lathes) and my work leads me to use some local cnc shops to make parts that we need in quantity or of high quality. The allure of 'doing it yourself' is what got me into black guns and I started out with a forged 80% lower conversion, have done a few raw forgings on the Bridgeport and finally just succumbed to having a local shop cnc the 80's and then I finished them from there. It's not hard, plenty of resources out there for doing the AR-15 lowers. They don't have to be pretty inside, but the holes have to be done properly and the pocketing has to be adequate to allow clearance for all the parts to move and also enough left on the sides to give it the structural strength required (which isn't that much on a lower receiver).

    AR-15s are about to be banned in MD, including finishing lowers, if the law withstands all the challenges. The only real option left if that happens for us is AR-10s or 308 variants as they are not affected presently. I'm done with AR-15 lowers, have what I want, now on to the 308 variants for a couple builds..
    Beware of Dog. Shoots to kill...

  6. #26
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    Quote Originally Posted by FloridaWoodsman View Post
    Has anyone done one of the plastic 80% lowers? YouTube videos make it look easy enough.
    Poly lowers would be much easier to machine, probably even on a drill press, but I just don't trust em yet... LOL
    Beware of Dog. Shoots to kill...

  7. #27
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    It may sound off the wall but you could practice on a bunch of 2x4's until you perfected the process.

  8. #28
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    Quote Originally Posted by polymorpheous View Post
    Drill presses are not intended for side loading.
    A vertical milling machine is.
    How well does a milling attachment for a metal lathe work?
    Train 2 Win

  9. #29
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    Quote Originally Posted by T2C View Post
    How well does a milling attachment for a metal lathe work?
    Hell if I know.
    I've only ever seen a lathe used for profiling and o-ring grooves in flanges in my line of work.
    I'd be curious to see how one machines a FCG pocket on a lathe.
    Quote Originally Posted by scottryan View Post
    Anybody that owns or sells pistol versions of assault rifles is a bottom feeder, irregardless of the ban status of certain ammunition.

    They are illigetimate weapons that have no real purpose other than to attract retards to the gun community.

  10. #30
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    Quote Originally Posted by T2C View Post
    How well does a milling attachment for a metal lathe work?
    I don't know about others but the one I have for my old Clausing,Atlas is almost useless! GH

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