80% AR Lower build

CStirling8011

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Was looking for general advice from those who have done the 80% AR lowers in the past. I have to jig coming in the mail and a couple 80% lowers. Have watched several youtube vidoes but don't have much experience with a drill press. Any info from past experience would be greatly appreciated.
 

Golddiggie

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I've done all of mine on a milling machine. I actually have three I need to process currently and another three on order (one AR10, one AR9, and one AR-45). I've got another AR9 and two AR15 80% lowers coming (soon I hope). Takes about an hour to process the lower on the mill. Including drilling and reaming the side holes. IIRC, it takes at least a couple/few hours to do with either the drill press or trim router. I've not used any cooling/lube in the past on the mill (I've heard of people using WD40 with the trim routers). IF I need to, I have a mist cooling system already in place that will be easy to employ.

I would make damned sure your drill press spindle is trammed to the bed of whatever vise you're going to use. Also use under sized drill bits and ream the side holes if you want to get them the correct size. Drill bits are NOT 100% round and can deviate from the listed size by enough to make it a PITA. I trammed the spindle to table and vise bed on my setup last night and made sure the vise was square to the spindle earlier today.

BTW, a few years back someone walked into a gun store I was in looking to get help with the 80% lower he had been spending several hours on. Hammer wouldn't fall properly. He got tired of using a file and Dremel to attempt to get it correct.

Yes I know people can do it with the drill press or trim router options. Just seems more complicated (to me) than using a milling machine. I also realize that not everyone can have a milling machine in their garage/home shop. Luckily I do have one.
 
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I’ve done probably 6-8 of them on a very cheap benchtop drill press. It’s tedious, but definitely doable.
Couple pieces of advice:

1. Make sure the end mill cutters aren’t set high enough to chew into the top of the jig.

2. Make sure the end mill is chucked into the drill super tight. I’ve had them walk out of the chuck and go straight through the bottom of the lower. (This can be fixed with JB Weld, btw)

3. I always use anti-rotation pins in 80% lowers, just in case the holes end up a tad funky.

4. My jig didn’t originally have a top plate with all of the little holes in it - just the outer perimeter. Later, the mfg came out with a separate top plate with the little holes. The little holes help a lot. Cuts down on a bunch of milling.

5. No matter how ugly they came out, every one of them functioned just fine.

Good luck
 

Individualist

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I've done all of mine on a milling machine. I actually have three I need to process currently and another three on order (one AR10, one AR9, and one AR-45). I've got another AR9 and two AR15 80% lowers coming (soon I hope). Takes about an hour to process the lower on the mill. Including drilling and reaming the side holes. IIRC, it takes at least a couple/few hours to do with either the drill press or trim router. I've not used any cooling/lube in the past on the mill (I've heard of people using WD40 with the trim routers). IF I need to, I have a mist cooling system already in place that will be easy to employ.

I would make damned sure your drill press spindle is trammed to the bed of whatever vise you're going to use. Also use under sized drill bits and ream the side holes if you want to get them the correct size. Drill bits are NOT 100% round and can deviate from the listed size by enough to make it a PITA. I trammed the spindle to table and vise bed on my setup last night and made sure the vise was square to the spindle earlier today.

BTW, a few years back someone walked into a gun store I was in looking to get help with the 80% lower he had been spending several hours on. Hammer wouldn't fall properly. He got tired of using a file and Dremel to attempt to get it correct.

Yes I know people can do it with the drill press or trim router options. Just seems more complicated (to me) than using a milling machine. I also realize that not everyone can have a milling machine in their garage/home shop. Luckily I do have one.
Great, when is the NES milling party? I’ll bring beer and chips.
 

schemingbunny

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Seen it done with a hand drill and router. Works, but NOT advisable. Takes way too long and risks chipping the end mill.
 

71montess

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I've done all of mine on a milling machine. I actually have three I need to process currently and another three on order (one AR10, one AR9, and one AR-45). I've got another AR9 and two AR15 80% lowers coming (soon I hope). Takes about an hour to process the lower on the mill. Including drilling and reaming the side holes. IIRC, it takes at least a couple/few hours to do with either the drill press or trim router. I've not used any cooling/lube in the past on the mill (I've heard of people using WD40 with the trim routers). IF I need to, I have a mist cooling system already in place that will be easy to employ.

I would make damned sure your drill press spindle is trammed to the bed of whatever vise you're going to use. Also use under sized drill bits and ream the side holes if you want to get them the correct size. Drill bits are NOT 100% round and can deviate from the listed size by enough to make it a PITA. I trammed the spindle to table and vise bed on my setup last night and made sure the vise was square to the spindle earlier today.

BTW, a few years back someone walked into a gun store I was in looking to get help with the 80% lower he had been spending several hours on. Hammer wouldn't fall properly. He got tired of using a file and Dremel to attempt to get it correct.

Yes I know people can do it with the drill press or trim router options. Just seems more complicated (to me) than using a milling machine. I also realize that not everyone can have a milling machine in their garage/home shop. Luckily I do have one.
Can we be friends ?
 

hminsky

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I botched a polymer lower. It was working really well with just a drill press, everything was going well, but I didn't follow the advice to use a hand drill
to do the holes for the safety, I used drill press instead. That was a mistake because apparently the hand drill will center itself in
the plastic jig, whereas the drill press stays in one place and doesn't automatically center itself. So the hole on one side was just a hair off and the safety wouldn't slide in
flush.
 

enbloc

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Hey, I’m good, thanks! Riding out the apocalypse at my empty campground in upstate NY. Coming back to NES more these days because it’s the only source of news that I’ve ever trusted 👍.
I think it's called a BIVOUAC now... [rofl2]

or, maybe a REDOUBT...

Stay healthy, stay safe, stay FREE.
 

jkelly1229

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I've done all of mine on a milling machine. I actually have three I need to process currently and another three on order (one AR10, one AR9, and one AR-45). I've got another AR9 and two AR15 80% lowers coming (soon I hope). Takes about an hour to process the lower on the mill. Including drilling and reaming the side holes. IIRC, it takes at least a couple/few hours to do with either the drill press or trim router. I've not used any cooling/lube in the past on the mill (I've heard of people using WD40 with the trim routers). IF I need to, I have a mist cooling system already in place that will be easy to employ.

I would make damned sure your drill press spindle is trammed to the bed of whatever vise you're going to use. Also use under sized drill bits and ream the side holes if you want to get them the correct size. Drill bits are NOT 100% round and can deviate from the listed size by enough to make it a PITA. I trammed the spindle to table and vise bed on my setup last night and made sure the vise was square to the spindle earlier today.

BTW, a few years back someone walked into a gun store I was in looking to get help with the 80% lower he had been spending several hours on. Hammer wouldn't fall properly. He got tired of using a file and Dremel to attempt to get it correct.

Yes I know people can do it with the drill press or trim router options. Just seems more complicated (to me) than using a milling machine. I also realize that not everyone can have a milling machine in their garage/home shop. Luckily I do have one.
You uh... wanna have me over for a glass or 4 of burbon when your next one shows up in the mail... show me how it works/ mill mine I'll bring the booze
 

jkelly1229

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I botched a polymer lower. It was working really well with just a drill press, everything was going well, but I didn't follow the advice to use a hand drill
to do the holes for the safety, I used drill press instead. That was a mistake because apparently the hand drill will center itself in
the plastic jig, whereas the drill press stays in one place and doesn't automatically center itself. So the hole on one side was just a hair off and the safety wouldn't slide in
flush.
Its ok I drilled through my rail on my first p80 glock build... luckily a light covers that sumbitch right up
 

GM-GUY

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Some advice on milling:

Wear heavy gloves to hold the part and jig under drill head.

Over speed on the bit can soften and melt the aluminum that will clog the flutes (grooves) and gum up the works.

The bit cuts in a clockwise direction, if you go the wrong way it will skip and make a mess or make the part jump out of your hand.

Shallow passes - taking too much will cause poor quality.

Don’t plunge with an end mill, use a predrilled hole as your start point.
 

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Did I do good Meg, did I do good?

 

Golddiggie

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Also keep in mind that if you put a side load on a mill in a drill chuck (as in drill press with a MT spindle/arbor) it WILL drop on you. The listed depth of the FCG pocket is +/- .010".

Coming set of lowers I plan to index off of a fixed position and use the vise stop to retain that point. Should make it easier to locate the side holes (do it by the numbers). I really only need to locate one of the holes since I have the distances for the rest of them. Thinking about using a 5/8" roughing end mill for the main FCG area and then just use some good two flute end mills for the rest (correct length of course).

I use the top plate of the jig ONLY to make the outline of the overall pocket. Mark the upper with either layout fluid or a Sharpie and trace that outline. DROs help make sure you get things right.

I didn't get the end mill, and all the other things I have for it, JUST to process 80% lowers. But it was one of the things that made the decision much easier.
 

jkelly1229

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I wish I could get some 80% lowers for a reasonable price. Been thinking of making some my self. Work in process
You into polymer I found a site that had 10packs with jigs for like 400ish... not that I don't need 10 lol just have other things I want to buy before joe

I'll split them plus I live in nh so I can get them shipped
 

Shark_Cage

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You into polymer I found a site that had 10packs with jigs for like 400ish... not that I don't need 10 lol just have other things I want to buy before joe

I'll split them plus I live in nh so I can get them shipped
Thank you but I don’t know about polymer. I would prefer metal if possible.
 

dhuze

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Seen it done with a hand drill and router. Works, but NOT advisable. Takes way too long and risks chipping the end mill.

My first one was with a hand drill and a router. It came out great. It just took a while to drill because pushing a hand drill down that long sucks. Then I got a drill press and use my router. Way easier to drill using a drill press.

OP, the best advice I can give you is don't buy cheap drill bits from HD or Lowes and such. Buy some metal drilling bit, preferably Cobalt. If they cost $2 they suck for anything but wood.
 

schemingbunny

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My first one was with a hand drill and a router. It came out great. It just took a while to drill because pushing a hand drill down that long sucks. Then I got a drill press and use my router. Way easier to drill using a drill press.
Agreed. Came out fine but the hours spent drilling was excrutiating... But hilarious for me to watch while enjoying a nice cold drink.
Go slow and shallow, like real slow with the router.
 
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