80% lower Build problem

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Brass2grass

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New here, first post. Hope this is the right section for this.

I went to the vallejo gun show a few weeks ago and bought an 80% lower from a guy. The company logo and all info had been machined off. He said that the company is no longer around. I ordered a jig from Daytona tactical and it came in yesterday. I was pretty excited for this build as its gonna be my fist 80. My excitement was soon killed. It turns out that my lower was less than 80% and would not fit in the jig. Now I'm no metal worker an I don't have a mill so I had to use a dremil tool and a sharp chisel to grind and scrape away at the receiver in a few spots to get it to fit.

Well after I managed to get all the parts lined up, I started to drill the safety, trigger and hammer holes. After I took the jig out of the vice and looked at it I noticed the safety hole is high and to the right and the pin holes aren't in line where they should be. I Assume this is from a receiver. I'm gonna go ahead and mill out the rest of it just to see if my LPK will fit.

The last picture is pretty rough. I've smoothed it out but haven't taken a picture yet. When I get off work I'll get some better ones.

Has anyone had any experience with Daytona jigs?
 
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I'm no expert on 80% lowers! or jigs.

But I think what you got is a DT jig, that fits DT 80% lowers.

And your lower isn't.

rc
 
The site says that it fits all mil spec receivers. I compared my lower to my RRA lower and the parts that I had to fix were different than the completed receiver. I think I may have got a less than 80 or just a jacked up one. Idk.
 
b2g,

I've done a number of 80% lowers from different manufacturers. There are two types of lowers, billet (totally machine cut from a chunk of aluminum) and forged. The billet ones, like yours, may not fit into a standard milspec jig. The billet ones have milspec dimensions in the critical areas but may be modified in other areas (thicker walls, different shape mag wells and trigger guard, etc). The forged ones usually fit most jigs. When doing some of my billet receivers I had to modify the jig to get it to fit the 80% lower. No mods were necessary for the forged ones.

While it is possible to complete an 80% lower with a drill press or router it usually gives less than stellar results compared to a mini-mill. Good luck.

best wishes- oldandslow
 
You must be!

Turn the jig clamp over so the curve on it matches the curve on the lower???

rc
 
Well, it's gotta be closer turned over then it is in the two photos you posted.

It is clearly upside down in both photos.

rc
 
Yea that was my fault with the pictures. After all was said and done I started my milling process. Needless to say, it was pretty rough. I don't have a mill or a traversing vice so the chatter was a pain and made the sides rough. For a first time build I think it went good. Learned a lot and know what to do next time.

http://youtu.be/sDBM8P_-sqk
 
Geeze!

No wonder you got rough cuts with what you are using for a drill press!

You do realize you can buy another lock-nut for your depth stop at any hardware store for .29 cents??

And you can buy a heavy cast-iron table vice at harbor freight for half what you paid for the 80% lower!
And even that weight will take a lot of chatter out.

I'm speechless you did as well as you did with that set-up!!!

Hate to see what you could do with a real drill press, and a real table vice!!!!

You could probably put Colt out of business!!!

rc
 
I bought a stop set while I was there but I couldn't get it to keep hold of the bit and it kept slipping off as well so I took a little at a time and checked with my calipers to make sure I didn't go to far.

I will definitely get a bigger and better press next time. This was a quick, I just off work set up.
 
b2g,

Making mistakes is good. It teaches you what not to do the next time. I damaged a couple AR lowers while learning to work a minimill but kept on milling until finished. They were used for milling practice and as test pieces for a home anodizing setup.

So keep on learning and good luck with the next one.

best wishes- oldandslow
 
Did you try to fit an LPK yet?

You may have issues with the selector, your oblonged hole allowing it to move where it shouldn't. But that is fixable. I can explain how if it proves problematic for you.
 
Not yet. I ordered it from Psa last week and it just shipped yesterday. As soon as it gets here I'll try and fit it in. How can I fix it? JB weld?
 
How can I fix it? JB weld?
Click to expand...

I suppose, but an insert is what I have in mind.

You simply make a larger hole in the right place, then drive bushings in, such as these:

http://www.ebay.com/itm/Mountain-Bi...125?pt=LH_DefaultDomain_0&hash=item25a4461c3d

You just make the hole a little bit smaller than the bushing (0.001"-0.002" undersize) so that it's a pressed fit. It's easier than it sounds, and even if you don't have a mill, reamers, etc, if you take your time, this is doable with a dremel.

Obviously you'd have to trim the bushings, but absent the ability to put metal back, that is the correct way to repair a hole that is oversized or not exactly where it should be.
 
Well after I managed to get all the parts lined up, I started to drill the safety, trigger and hammer holes. After I took the jig out of the vice and looked at it I noticed the safety hole is high and to the right and the pin holes aren't in line where they should be. I Assume this is from a receiver. I'm gonna go ahead and mill out the rest of it just to see if my LPK will fit.
Click to expand...

On all of the lowers I've done, the last thing was to drill the trigger/hammer/selector holes. Drill bits, even in a good press or mill, are not the most accurate critters out there and will drift as you drill deeper. That's why I drill each hole from each side after finishing the pocket.

I don't have a mill or a traversing vice so the chatter was a pain and made the sides rough.
Click to expand...

Drill presses are not designed for lateral loads in the first place. Mills and routers are. This is the primary reason I went with the 80% arms jig.

I will definitely get a bigger and better press next time.
Click to expand...

Tools on the low end have a pretty high marginal utility... $10 saved on a tool will often cost you $100 in time.
 
Figured out the problem I was having with the hammer not falling. The freaking pin holes are too close together. Measured the jig and it's at .84 all my factory receivers are .90. I'm so pissed off and the company that made the jig Daytona tactical stated that all sales are final and they don't accept returns. Wth is that bs
 
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You mean to say she's complete, and works?

Or you mean to say the pin holes are still too close together and it still doesn't work??

Rc
 
Since my jig was off I welded up the holes and scribed them by hand with calipers from CNC plans. Everything moves smoothly and function checks cleared. Just need to throw some paint on it.
 
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