80% Lower finishing step

[Gatorade]

Okay, I want this to be simple as possible to follow so I am creating a new thread with the stages i did it in. Acquiring the materials, drilling, milling and assembling. I don't have time to do everything at once but will update the thread as I am able to.

Here are the materials I either bought or already had

80% lower
http://www.rangetool.com/store/index...80percent.html

80% lower jig
http://www.rangetool.com/store/index...lower-jig.html

End Mill
https://www.midwayusa.com/product/84...m-1-4-end-mill

Other tools I either already had or are general purpose:
5/32, 3/8, cobalt drill bits
Harbor Freight drill press
WD40
Shop vice

[Gatorade]

Assembling the jig and drilling the safety and trigger pin holes.









I switched the clamp to a metal clamp that was made for drill presses for the second Lower. The metal clamp was much stronger and made drilling easier. I went a little too fast with one of the holes and there was some binding that stopped the drill. I tapped the jig off the bit, added some WD40 and went slower.

One other note, I am doing two lowers so I wanted to drill these holes with fresh new bits. Drilling the holes for removal of the material in the trigger pocket may wear the bit so I wanted those holes drilled with new bits.

[Gatorade]

My jig set didn't have the drill guides so I had to free hand it, I tried using the 5/32nd bit to drill pilot holes for the 3/4 bit. That didn't work out so well for me. I didn't want to make a mistake so I only went about half as deep in the pocket and will go deeper for a second adjustment. The smaller holes were not aligned with where the larger ones would be and I was going at too slow a speed. Looks a mess and I was not happy but was going to see how it would be after the end mill went in. I got a little close to the guide on a couple holes.





The endmill did its job and my lack of machining skills are evident. I did read up last night and found out my drill speed was way too low. Speeding up the drill worked better with the endmill but it was pretty rough and lots of chatter if I tried to push it too fast. When I got deeper I was able to use the jig top plate as a guide for the smooth shank of the mill.



Not finished but looking better. You can see the trigger pin holes and I have re drilled deeper with the 3/4 bit. Faster speed made that much easier. I am leaving the back section for right now because that is a different depth and I want to get the main pocket cleared out first.

It won't win a beauty contest but I have heard some sand paper and a dremmel may help the smoothness on the inside. Truth be told I would be happy if it just functions well no matter how it looks inside. This is the first and I will be doing more so I can only hope to get better as well.

More milling later!

Milled out the front pocket and the safety pocket. Could have gone a little farther on the safety pocket but it looks like it will clear everything. Put the drill guide for the trigger slot. Two big holes should have been easy but looks like I walked one one the holes just a bit.



Finished milling! (Or so I thought!)

[Gatorade]

Stripped the parts off another build and assembled them!

The trigger pin holes are not as tight as my other factory lowers. Anti-roll pins will take care of that.



The rest of the assembly went great! Safety works, trigger works. Bolt catch works, mag release works all set!



The rear take down shelf was already milled out from Range Tool. I left it as is and it looks like it may be about 1/64" or 1/32" too tall. The rear takedown lug on one of my uppers wouldn't fit. I am going to try and smooth the insides out with a dremmel sander and that should also take the top off that rear shelf. One of my PSA uppers fit but I had to get a punch and force the rear pin out to remove it.



On the whole it is my first pretty much complete AR lower. It functions and is not pretty but looks like it will be functioning soon! Woo Hoo!

[Gatorade]

Testing and range report

[RKP]

May I suggest to that this thread become a 'Sticky'.

[Gatorade]

Originally Posted by RKP

May I suggest to that this thread become a 'Sticky'.

I would be happy if the other thread was un-stuck. This is a better thread than the original.

[Caleb]

Nice! I love project threads. Looking good bro.

[Gatorade]

Updated with milling and drilling pics.

[RandallZ]

May I suggest you use the top plate as a template rather than a guide? If you scribe a line on the 80, then remove the top plate you can use the line as your guide and save the plate from being chewed by the bit or end mill.

Randall