80% AR lower tips?

[Texas by God]

I'm going to build a couple of these in the future. I have the 80%Arms gen 2 jig, bits, two 80% lowers and all the stuff to make 2 5.56 ARs. Any tips for a first timer? This project kind of fell in my lap so here we go.
Thanks in advance!

Sent from my SAMSUNG-SM-G930A using Tapatalk

[trails4u]

Drill press and patience. And don't drill quite as deep as the jig....I mean not by much. Will be much cleaner with the endmill on the router as you won't have the drill tip dimples left behind....

[rancher1913]

use a quality jig, the ones that you drill and dremil out are crap for a hobby guy to get right. I got the 5d tactical that uses a router and if I take my time you can not tell it from a factory one.

[Texas by God]

Yes, this one uses the router. Good stuff, any videos you recommend?

Sent from my SAMSUNG-SM-G930A using Tapatalk

[Sig556r]

lotsa patience, measure twice/cut once...

[cwtebay]

I'm a little different I guess, I like the drill method. I use the included plate but then drill between the large holes with a 1/16" bit until no more holes will fit. Then I use a router to finish the material removal. I use headlight buffing compound to polish. There was a video on this on YouTube but I think it must have been taken down since I last used it.

Sent from my Pixel 3 XL using Tapatalk

[cub45]

Use a milling machine, you have total control and can see what you are doing.
I've done a few.
kurt get a long 2 flute tool

[cub45]

oops, tried to edit, should be gap between kurt and the get 2 flute tool stuff

[merlin101]

Short of a milling machine the router method is next in line. When using the router chips fly EVERWHERE! After doing the first one I used a cheap harbor freight blue tarp and cut a hole in the center big enough to fit over my vice, the tacked up the back and sides. That made clean up a breeze. Cut slowly and carefully wear PPE! Make sure you check the collet is tight especially for the final cut they seem to want to loosen and the bit slides out making a deeper cut ending with a cut all the way thru the trigger area! Pay special attention to the difference in depth, notice that the rear is not as deep. Don't forget gloves, al. slivers are small and hard to get out.

[cwtebay]

Short of a milling machine the router method is next in line. When using the router chips fly EVERWHERE! After doing the first one I used a cheap harbor freight blue tarp and cut a hole in the center big enough to fit over my vice, the tacked up the back and sides. That made clean up a breeze. Cut slowly and carefully wear PPE! Make sure you check the collet is tight especially for the final cut they seem to want to loosen and the bit slides out making a deeper cut ending with a cut all the way thru the trigger area! Pay special attention to the difference in depth, notice that the rear is not as deep. Don't forget gloves, al. slivers are small and hard to get out.

Excellent point, long sleeves and gloves (and something to keep them from going down your neck!!!) and face protection are definitely necessary. I built a mount for a shop vac on my vice which helps a ton. Good quality cutting oil helps with keeping the chips under control also.

Sent from my Pixel 3 XL using Tapatalk

[ScrapMetal]

I haven't used the jig/router method and have only done it on my mill. The number one thing (after safety) that you need to make sure of is having a solid, stable vise to hold the work.

I made a set of vise jaws to hold mine. There are some pics at the start of my first 80% build at AR lower build



-Ron

[Texas by God]

It turns out that the router adapter is not present but Midway to the rescue. No directions either but the video is good.
I don't have a mill- yet.....

Sent from my SAMSUNG-SM-G930A using Tapatalk

[justashooter]

parts kits from palmetto state are reliable lately.

[nun2kute]

WHOA !!!! Scrapmetal Dude !!!! You stopped Waayyyyyyy to soon with the pictures. ! We need to see that whole process, step by step. With NFL instant replays. PLEASE !!

[ScrapMetal]

WHOA !!!! Scrapmetal Dude !!!! You stopped Waayyyyyyy to soon with the pictures. ! We need to see that whole process, step by step. With NFL instant replays. PLEASE !!

Okay, but if this is deemed to be too "off topic" for the OP I'll pull this post. I'd hate to hijack someone's thread.

I started with a set of 6" x 3" x 1.5" aluminum soft jaws from Monster Jaws, fired up the mill.



Here is a shot of the completed "first operation". I set the quill stop for the proper depth and then "went to town" on drilling.



I pulled the lower out and swapped out the jaws to do some other work and here I put the drilled out casting back in the vise and used the DTI to make sure it was true with the mill.


I installed the pivot pin and touched off of it with the edge finder to set the "0" on my X-axis.


To set the Y-axis "0" I touched off one side of the casting, set the zero on my DRO, then switched to the other side and used the "1/2" distance function to find the center line.


Finally, here is a shot just as I'm finishing up the plunge/roughing out.


Finished with the firing mechanism cavity.


Switched back to a set of flat jaws and used some spacers to set the lower on it's side, level, and with enough clearance to drill through.


Installed a 1/8" spotting drill and marked the location.


Followed that up by drilling a 1/8" hole all the way through both sides of the casting.


End of part I see next post for part 2.

-Ron

[ScrapMetal]

Continued from part I

To finish out the first hole I used a 5/32" chucking reamer. Back gear and around 80 rpm.


Now it's on to the hole for the safety selector. Now with a 3/8" spotting drill.


In the next pic I used a 23/64" drill to make the hole through the casting. I could have maybe used a 3/8" but I don't trust the drills to be accurate and that would have left very little room for error.


Like the previous holes I chucked up a reamer, 0.376" this time, and put the finishing cut on the hole. Here you can see where I had to slide the aluminum spacer out of the way. Once again, back gear and 80 rpm.


The "finished" lower (sorry, I didn't take pics of milling out the hole for the trigger.)


A shot of the test fitting of both the hammer and trigger assemblies. I disassembled it and hit the milled area with Brownell's Aluma-Hyde II paint.


Finished lower waiting for upper.


I finished it up with Troy Industries folding battle sights, front and rear (in the lower picture the eyepiece is moved to the side in order to raise the rear sight), an EoTech holographic sight and magnifier, and all Magpul furniture. The Troy battle sight is high enough so that it can be used without removing the EoTech sight though it might not look it from the pictures.


Sorry for all the pics/detail but I tried to trim it down to the essentials (I really did!)

Let me know if this was too much,

-Ron

[nun2kute]

Beautiful !!! TY !

[Texas by God]

Actually kind of fun this way.

Sent from my SAMSUNG-SM-G930A using Tapatalk

[cwtebay]

Actually kind of fun this way.

Sent from my SAMSUNG-SM-G930A using Tapatalk

Ok, that's cheating!!! But in a fabulous way!!

Sent from my Pixel 3 XL using Tapatalk

[BNE]

Ron,

Thank you for the pictures and guide. I had always wondered what was involved.

Texas by God: - What are you showing? We need more details / pictures!

BNE