80% Receivers On A Lathe Milling Attachment???

cdhknives

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I've been wanting to complete an 80% AR15 receiver and reading everything I can find. My equipment is a 20 year old 15 speed drill press and a well used but serviceable 10x36 Atlas lathe with the milling attachment that replaces the compound.

Most of the talk is that the drill press alone just isn't up to the task unless you like sloppy work. I can see that.

I have used the milling attachment for a couple of small jobs, like making a t-nut for a quick change tool post, and rigidity/chatter was an issue. From that I assumed using this for milling the 80% receiver would not work well...but the more I think the more I question if I'm overthinking this. It's aluminum, not steel, and while it would be hanging pretty far out could I use high spindle speeds and light cuts to get the job done?

Yes I know a true mill would be better, but with the "must own your tools to complete a receiver" ruling I'm limited to what I have and a mini-mill isn't in the budget anytime soon.

Should I give it a try or am I going to be chasing my tail and ruining parts?
 
On the lathe it would be a challenge. I don't think you have to own your own tools, just have to do the work your self.
 
I don't see why you couldn't accomplish this on a lathe. In reality all you are doing is cutting a slot or two in aluminum. Once you have the lower fixtured in your milling attachment just clear out as much material as you can by plunge cutting. You can then take a long 7/16" end mill to finish the sides, corners, and bottom of the main slots. Here is a shot of a lower where I had just finished up the plunge cutting:

arlowerjig15.JPG

When doing the plunge cutting, as well as the finishing, just make sure you keep the cutting path clear by getting the chips out of the way. I used a vacuum attachment that I positioned over the cut as it was being done. It'll make for a much cleaner cut.

Best of luck,

-Ron

arlowerjig15.JPG

arlowerjig15.JPG

arlowerjig15.JPG

arlowerjig15.JPG

arlowerjig15.JPG
 
Don't see why not. I think I would use your DP first to rid the slots of a bunch of material where possible. Drill bits plunge better than even center cutting EMs. Leave some around the perimeter and then go light on the milling cuts with your lathe and attachment.
 
As a part time gun smith I've done a couple of these. I can't imagine doing this on a lathe, or without a drilling fixture. Check out kearms.com; americanspiritarms.com or acttactical.com. will get you a high quality tool and instructions. Also I recommend downloading a set of blueprints for exact tolerances. If you can look for a back issue of ShotGun News, 15th. annual edition, has a four part article that will save time and grief. Dave..............
 
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As a part time gun smith I've done a couple of these. I can't imagine doing this on a lathe, or without a drilling fixture. Check out kearms.com; americanspiritarms.com or kearms.com. will get you a high quality tool and instructions. Also I recommend downloading a set of blueprints for exact tolerances. If you can look for a back issue of ShotGun News, 15th. annual edition, has a four part article that will save time and grief. Dave..............

Not to undercut what you're saying but it's my experience that a drilling fixture creates more problems than they are worth and really only good for trying to finish a lower on a drill press. A lathe is a VERY capable tool and in this case just think of it as a "horizontal mill" using the head stock as the milling head. With careful measurements or, better yet, an attached dro or iGage readout, I don't see why it would be that tough. It's not like we are talking about compound angles, etc. in the process.

JMHO

-Ron
 
Hi Ron. I agree totally, I've done a lot of projects with my milling attachment on the lathe. And it wouldn't be that hard really. I just meant that having a mill I couldn't imagine using my lathe. Using those jigs are the best when it comes to getting your holes right and keeping everything square with the quill. I drill my holes from both sides, not all the way through as they recommend. I didn't like using the guide for the fire control well though. Rather I used Dykem to ink the well area and scribed out the area to be milled using the guide for a template and milled them out without the guide according to the prints. Worked well for me anyway. Thanks! Dave
 
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It's very doable. A set of side plates is useful for clamping the irregular surfaces. For the fire control group pocket you don't need complex tooling. A 7/16" end mill that will cut 1.25" deep, 5/16" end mill for the trigger slot and drill bits to remove the bulk. Please follow up if you do the project.

Dave
 
Hey!!! Finally a question I can actually offer some insight on! I'm somewhat new at this, I just got my Atlas 10x36 a few months ago. The answer is yes you can, and it beats the heck out of a drill press. I did one on my drill press a year or so ago with the Bareknuckle defense jig kit and it turned out OK, but it took forever to do a good job and I swore I wouldn't do another until I had better equipment. I just did one on my Atlas 10" with the milling attachment a few weeks ago and was amazed at the difference. Surface finish was good, and as long as you don't try to climb mill, chatter was not an issue. I still used the jig to locate the trigger, hammer and selector holes and to remove as much material as possible with a drill bit. After that I found it easier to take the lower out of the jig and clamp directly onto the flat where the pistol grip goes. Worked like a charm.


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Thanks for the replies! Yes I fully intend to buy the full jig set. I did have a thought about dykem and marking vs. actually machining through (and probably nicking) the cutout templates. I do not have a DRO and do have a lot of slop in the cross slide screw, but I'm working to get that taken care of. Since the billets are on backorder (probably a mistake to use Ares, oh well), I'm still in the thought stage anyway.
 
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