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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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!
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.
Has anyone done one of the plastic 80% lowers? YouTube videos make it look easy enough.
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… 
Poly lowers would be much easier to machine, probably even on a drill press, but I just don’t trust em yet… LOL
It may sound off the wall but you could practice on a bunch of 2x4’s until you perfected the process.
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.
I don’t know about others but the one I have for my old Clausing,Atlas is almost useless! GH
I’m sure it would work fine. In fact, I’d rather use the attachment before a drill press any day. Realistically though, unless it’s a small garage hobbyist, chances are if someone has access to a lathe, an actual mill would probably be parked nearby.
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You would be better off finding an aluminum supplier or shop where you can get a scrap of aluminum (preferably 7075) and practice with that… milling wood and alum are quite different animals… .lol