AR blank machining

[yamaha415]

I see alot of threads about 80% builds, but has anyone taken on machining one from a blank casting?

[darkcbr1000rr]

Takes too much time if you aren't doing it cnc. Too many operations.

[jamesob]

I tried one along time ago, almost did it right to.

[Bhobbs]

I have a 0% forging at home and I want to try it but I have access to 3 CNC mills at work I can cut it on.

[punkur67]

We talked about doing some on my friends cnc mill. Just one of those projects that there is not enough time for at this time. I would really love to do some ar 10 lowers too.

[VaderSpade]

I have a new CNC mill ordered, and I plan to do a couple just to say I did, but unless you have a big CNC with tool a changer and you’re doing big batches I don’t think they are worth the time.
Now billets that let you draw outside the lines those will be worth the time.

[P.Charm]

I was just talking with my co-worker (CAD drawer; is that the right term?) he has the full CAD drawing for an upper and lower semi-auto AR. I'm sure it would just take us going to our machine shop and jump on the CNC, but how many hours do you think it would take to cut one? I would assume alot. but then, how about a 0% would it be the same drawing?

[darkcbr1000rr]

Haha. Machining isn't just taking a drawing and walking into a machine shop. You have to put a tool path to your geometry, figure out how to hold the part, knowing your speeds and feeds, calculating for certain ops (like thread milling), and knowing which tool to use.
And make sure your CAD drawer knows how to use a CAD/CAM program.

[Nathan Krynn]

Yeah take it from me it isn't worth it for you the home builder. Even most machinists.

First the magwell. You can not machine out the correct magwell. It is impossible to make a square cut with a round tool. You need a broach or EDM. You can plunge ears in the corners to give you clearance but most of the time I see this people fail to do it correctly. (like my technical terms).

Next the print is 50 years old and ridiculously over complicated. So handing it to a machinist with their labor rate you will loose an arm or leg before you make chips.

I even highly recommend getting a jig as the time involved without one you will loose time and money locating properly, and making soft jaws or your own jig. I cant tell you the times I have asked customers if they want a jig and they reply "no I'm a machinist", Then get a web order of a jig a week later. Can you do it without, sure. But is it worth the time and material involved to do so?

Seriously 80%'s are the way to go, simple and WILL save you time and money, as will a jig.

[Calif Mini]

0% Ar-15 Machining guide

If one has to try it on their own...................

Check out Ray-Vin. Ray Brandes.

https://www.ray-vin.com

Or go direct to here ......

http://arlower.ray-vin.com/ar15/

[Joewy]

For a AR-15 lower, 7075 billet is more than $45. 6061 is cheaper but still around $30. You can pick up 0% 7075 forgings for less than $20 http://www.baforging.com/m-16-and-ar-15-components.html and most of the profiling is already done. You can make your own broaching tool for the mag well and plunge cut it using M19 on fanuc contols after milling it out with a center cutting end mill.

M19
G10 L50
N4077 R(xxx) (depends on angle)
M19

You will have to reorient the spindle prior to tool change using N4077 to the original angle.

Unless you have lots of skill and lots of time it is better to buy a 80% lower.
However there is nothing more satisfying than doing it yourself.

[FashionBiff]

I tried one along time ago, almost did it right to.

Not a dig but this made me LOL.

[Holescreek]

I've done a couple, the hardest part is the mag well. Rather than buy a tap for the buffer tube I caved in (cheaped out) and helical thread milled the threads on my CNC. The rest of the machining I did on a manual Bridgeport.
As a real machinist that is old enough to know how to run a manual mill (and not just push buttons) I will tell you that unless I'm running a lot of parts, I can finish the machining manually in the time it takes to get the CNC set up.

What everyone's saying is true though, it isn't worth the time for me to even machine an 80% when Aim will sell you a perfectly good 100% for $59.

[couch]

Please tell me you made that PRS yourself!

[Holescreek]

I had to look up "PRS" to see you meant the stock. Yep, all home made. Had to make a special length buffer tube to use it though. My point is that when so many people on internet forum tell you that you can't do something, no one tries. A lower is just a piece of aluminum.