Am thinking of doing my first 80% receiver but would like to have more info. Anybody here ever done one and which method of drilling the holes is preferred?
press to drill the holes, then the small router to cut it out. stay with the guide measurements on poly, 1/2 the measurements on alloy use a decent jig. I use the gen 2 but the three wasn’t out yet. if you get one of these get the sideplates as well.
for drilling the holes its too easy to drift with a hand drill.
If you go to that link I sent you … that guy explains how to do it right and fit and finish… he also sales tool kits and stuff like that
I started out with the drill press and gave up on that in about 5 minutes. Got online and found a print with all the dimensions for a lower and put it on a Bridgeport mill. Only took about 30 minutes and came out really nice. Owning a machine shop for 31 years now I was fortunate to have the knowledge and equipment to do the job.
Did have a buddy who has never even shot an AR machine and build his first one using a router. His also turned out nice. He did spend quite a bit on his fixture and router though. All of the ones I and my buddy did were from 7075 aluminum forgings.
The drill bit method would be a LAST resort.
Router hands down. It can be done with a drill press however it’s easier and more accurate with a router. Several outfits offer jigs along with cutting bits, either as a kit or a package deal. Most will usually recommend specific routers and have the correct end mill for it.
Concur with Festus.
I have a mill, a drillpress, and a router. Do ar15s, ar308s, and 1911s.
The router and 5D jig is the ticket for ARs
I would just add, take your time. Use a good cutting oil and have a shop vac attached to the port on the jig.
For me i have only milled 6 lowers out so far 2 poly ar15 lowers 3 billet ar15 lowers and 1 billet 308 lower. I done the first poly lower with router and it worked out pretty good but i really like my drill press with xy milling vise. Ive got a couple good jigs and i invested in a couple good end mills. The end mills make all the difference. I used the end mill that come in kit for first couple lowers and had alot of dremel clean up to do. But after forkin over 45 dollars each for a couple top shelf end mills the difference is night and day. And like the guys here have allready said use some good tools and good cutting oil on your aluminum lowers and take your time. Remember you can allways take a little more out but cant add it back.
Nothing like a sharp, quality mill bit.
Been sending mine out to a company in OH getting them re-sharpend 8 or 10 at a time, they will also do TiN and other coating. Was going to get a sharpening grinder but $$$ and no shop space left, glad I gave them a try.
If you can get access to a mill that’s as good as it gets. Like @HandyDave said a good premium end mill is the way to go. I used solid carbide mills and ran them dry, no cutting oil or coolant but did have constant air blowing to keep the chips evacuated out of the pocket.
Love solid carbide but almost cry when I accidentally let one drop out of the collet and hit the table.
Use a misting system lots of pressure to keep the cut clean and a little cutting fluid to keep things cool.
Yup, when I downloaded prints from online I noticed that also. I chose the print that left the most material. Actually machined mine so they have a slight interference fit with the upper. Last step was to mark it with the date made and that’s where things went bad. Lower moved while marking it.
Van Norman Knee with a cold air rig and carbide…poly’s with a router, its easier and a lot cleaner than running them on single point… 7075 and billet, i let the big dog eat.
talk about sharpening bits. I have 1 wheel for a grinder i use for carbide. that wheel cost me 500$ 12 years ago. it stays in the locked, only i get to use these tools box.
I’m guessing that’s either an Elgin or Norton diamond wheel.