80 Percent Builder Forum

80% Lower Forums => 80% Lower Builds => Topic started by: 7.62X39 on January 20, 2016, 02:00:45 PM

Title: 80% receiver finishing tips
Post by: 7.62X39 on January 20, 2016, 02:00:45 PM
Just a few things that I've picked up along the way.

A short piece of 1-1/2" painters tape is just the right size to protect the lower while performing the machining operations.

(http://i395.photobucket.com/albums/pp31/aksmith762/tape_zpsgrv7g3si.jpg)

A 1/4" clevis pin not only works well to secure the front of the jig, it also makes a handy tool for installing the pivot pin detent and spring when the time comes.

(http://i395.photobucket.com/albums/pp31/aksmith762/setup3_zpsswytoogc.jpg)

 It is very important to keep the chips cleared out while machining. Unfortunately I was born with only two hands (both of which are kept firmly around the router) so I came up with this handy, dandy vac attachment out of a piece of 1" copper pipe and some 1" hose from Lowes.

(http://i395.photobucket.com/albums/pp31/aksmith762/vac2_zpsxg53tg2p.jpg)

(http://i395.photobucket.com/albums/pp31/aksmith762/vac3_zpsnkdoa2ga.jpg)

Just be sure to keep it way away from the machining area. I secured mine with a copper pipe hanger

(http://i395.photobucket.com/albums/pp31/aksmith762/vac4_zpssnroc4l1.jpg)
Title: Re: 80% receiver finishing tips
Post by: 7.62X39 on January 20, 2016, 02:06:34 PM
While on the subject of drilling, I have a certain order that I like to use. Imagine the holes in the drill guide numbered 1-9 top to bottom.

(http://80percents.com/smf/images/drillguide_numbered.jpg)

I like to start out with Hole number #4 which is the only "A" hole. Then I drill #8 which if using a gen ll receiver will be the only "B" depth hole.
Then set your drill to "C" depth and drill the rest of the holes in this order #1, #3, #2, #5, #7, #6. You will not be drilling #9 if you have a gen ll lower. By doing them in this order you will keep any tension equal on both sides of holes #2 & #5. I feel that it is worth consideration because those two holes are extremely close to their neighbors.
Title: Re: 80% receiver finishing tips
Post by: helidude350 on January 20, 2016, 03:56:04 PM
"A" hole...... ;D

I almost spit DR B through my nose.
Title: Re: 80% receiver finishing tips
Post by: helidude350 on January 20, 2016, 04:07:14 PM
If you buy a second drill guide, ( modulus replacement parts ) you could set one up like this and leave it that way.

That's a cool set up for the vacuum.  ( almost as cool as the bucket idea ;))

I am wondering if the "A" hole is too close to the adjacent "c" holes to cause the grabbing issue that I noticed on my 308 jig?  ( I omit using one of the aholes on that one)
I could use your bushing trick in the adjacent c holes if I find I have an issue with it when I get mine.
Title: Re: 80% receiver finishing tips
Post by: Jefe on January 21, 2016, 10:13:45 AM
Thanks for the detailed tips. I downloaded and then numbered your drill guide photo. I replaced your photo with the new numbered photo. I also created a second version that is numbered in order and color coded for depth.

(http://80percents.com/smf/images/drillguide_ordered.jpg)

I once tried to pre-drill with 1/4" holes but it didn't seem to help like I thought it would. Instead of bushings I just drilled slightly with the 3/8" bit to make a center mark for the 1/4" bit. Of course that only works with a drill press and if you are using a hand drill then a bushing guide would be a very good idea so you don't end up drilling at an angle. I explain what I tried in this topic.

http://www.80percents.com/smf/index.php?topic=35

I'm glad I'm not the only immature mind who laughed at "a" hole :)