80% jigs

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So, I'm toying with the idea of building an 80% lower for my .300BLK pistol build, but I've never done it before. While it's not a 'budget build', it is a build on a budget. The core parts I'm still lacking are lower, barrel and gas tube/gas block, and handguard.

Since I know we have plenty of 80% lower experience here, what's the best bang for the buck when it comes to jigs? And 80% lowers, for that matter? Looks like no matter which way I go, it's not going to make $$ sense to go the 80% route unless I do at least a few of them or convince a few friends to build 80%'s and go in on the jig. Even at that, blem lowers can be had for about the same price, but, whatever. I want to do it this way.
 
Well, if I was making a few, and some friends were making a few, I'd consider going in together on a used "mill-drill", rather than a jig. It's easier to do right with a mill, and you'll find lots of other fun projects to make later on. Or just sell the mill when done.
A small mill-drill can be found used for ~ 600 or less, depending upon size.
 
There are jigs available from the Ares Group buy for loan. Talk to Golddiggie about one.
They are the AimSmall jig.

Malodave
 
The jigs are made by aimsmall on calguns.net... You'll still need access to a proper mill in order to machine the lowers, held by the jig. You'll also want some specific end mills to do the job. DRO's, while not critical, will ensure you don't have any ****ups while machining. While you can get a mill for ~$600, you'll also spend another $150-$300 on tooling to make it functional. That includes a good vise, collets (to hold the bits), end mills, etc. Then more on good DRO's (don't get the cheap ones, spend the $$ to get good ones). By the time you're done, you'll spend another $600+ to get that mill to an usable state.

If you don't want to spend that kind of money, but still want to go the 80% route, PM me. I can help you out for a lot less $$. [wink]
 
Yup, you can spends LOTS o cash on tooling! For doing some "80%" lowers, you won't need too much though. A couple colllets, a drill chuck, an end mill or two, an angle plate, a few clamps, and maybe a dial indicator & edge finder. Shouldn't even need a vise. Many used mill-drills will come with most of the above. Mine did.
Sell it all when done if you have no further need for it. But trust me, you'll want to keep it for other fun stuff [smile]

DRO's are nice, but really no need for a small project like an "80%" lower. I don't even use mine most of the time - just keep count of those dial turns. [rofl]

Also, if you have a mill, no need for a jig at all - just make some cheap clamping plates out of scrap 1/2" aluminum plate (see the "Ray Vin" tutorial).

PS - I have some tooling available for the job (drills, reamer, - maybe some other stuff - send a PM if interested).
 
DRO's are nice, but really no need for a small project like an "80%" lower. I don't even use mine most of the time - just keep count of those dial turns.

The problem there is that these Sieg X2 clones (harbor freight, grizzly, homier, cummins) that most of us bought use a funky calibration. Oddball pitch on screw leads for some reason. Straight counting turns doesn't work. I said screw it and add the DRO's. Easy peasy now.

http://www.northeastshooters.com/vbulletin/threads/202496-Finishing-80-AR-receiver
 
Bits needed to properly process an 80% lower:
5/8" two flute end mill with flute length between 1.25" and 1.5"
7/16" two flute end mill with same flute length as 5/8" bit
5/16" end mill long enough to reach about 1.5" deep to cut trigger slot. A 2.5-3" bit is good.
#23 drill bit and .156" reamer (or drill bit/reamer combination). Used for the hammer/trigger pin holes.
U bit and .375" reamer for the safety/selector hole.

The jig has real advantages such as placement for the holes you need to drill. Without the jig, and solid DRO's, you're just being stupid (IMO). I've seen what happens when people either use shitty jigs. Without a solid/proper vise, your chances of getting true holes is remote. Also, with the good jigs, you have a much higher success rate, and the lower looks damned close to factory finished. With a proper mill (not the cheap mini mills you see) your time to process is significantly less. I went from 2.5-3 hours on a mini mill to an hour on a proper (knee) mill. The knee mill has proper DRO's on it, so you can do it by the numbers. You still turn the handles to move the table, but you have less to worry about. Also, the rigidity of a knee mill simply cannot be matched by the small mills.

BTW, sure, you can finish an 80% lower with a drill press and dremel tool. If you don't mind it taking several hours and maybe not working properly even after all that time.

AS I had mentioned before, if the OP wants to get his lower processed, he can PM me. If he doesn't mind it looking like ass, and maybe functioning properly, then he can go with Archilochus' method. IME, doing it right actually takes far less time than trying to do it ghetto. Plus the end result is often night and day.
 
Perhaps I should have mentioned - I don't have access to a mill. A big old beastly drill press with an X/Y vise, I do have ready access to. Is this a fools errand to attempt it without a mill?
 
Perhaps I should have mentioned - I don't have access to a mill. A big old beastly drill press with an X/Y vise, I do have ready access to. Is this a fools errand to attempt it without a mill?

With the X/Y vise, you cannot mill. Put side load onto the drill bit (or even end mill in a drill press) and your chuck WILL drop. Unless you have one of the drill presses that actually uses a draw bar to keep the drill chuck in the spindle.

PM me, if you want to connect up to use a proper mill.
 
With the X/Y vise, you cannot mill. Put side load onto the drill bit (or even end mill in a drill press) and your chuck WILL drop. Unless you have one of the drill presses that actually uses a draw bar to keep the drill chuck in the spindle.

PM me, if you want to connect up to use a proper mill.

Supposedly this drill press does - been meaning to check for myself, since the person I asked might have remembered seeing a trailer hitch in the same shop bay as a cordless drill and got confused. (He's that guy)

More I look at this, the more I realize how much more expensive it would be than just buying a $60 blem lower. I'm not sure if I'd save money by not being able to do it, or spend much more having an excuse in mind to buy a mini mill next time I see a good deal on one.

Really appreciate the offer to use a mill, but I'm stationed out of state right now. Hopefully forever, in fact - I don't think I could take moving back to MA after living in Oregon for a few years.
 
Cnc guns fixture you use a drill press . If your drill press spins fast the little bit of metal left after drilling won't effect it.
You can also you the jig and a router for the clean up.
 
....Without a solid/proper vise....

I dunno, I (and friends) have done a bunch of "0%" & "80%" lowers with no jig and not using a vise - just the table and a 6" angle plate. This on a Rong Fu RF45 - one of the larger of the small mill-drills. (yes, I have a good vise - Kurt D675)

I bought it (~600 with tooling & DROs included) instead of a jig, with the idea to sell it when done - but cool projects just keep coming along - All sorts of fun possibilities [smile] A jig has only the one use.
 
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The problem there is that these Sieg X2 clones (harbor freight, grizzly, homier, cummins) that most of us bought use a funky calibration. Oddball pitch on screw leads for some reason. Straight counting turns doesn't work. I said screw it and add the DRO's. Easy peasy now.

Yup - my mill-drill (RF-45) is the same. On mine, it only really matters on cuts longer than about 5" - longer than that and the DRO's get switched on. For shorter cuts, the error is well within tolerance for most work. More precise and I'd use the Bridgeport at work.
 
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