80% oops, subsurface broken bit

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Or better yet just don't fool with aluminum 80% lowers

Aluminum is a very easy metal to work - the cutting forces are low, it doesn't work harden, and so on. You can work it with woodworking tools like routers and tablesaws.

It's really unfortunate that you had a hard time, but I'd hate to see folks put off from trying. I'm not sure the difficulties you encountered are common.
 
Pinter, your probably right. I am really wondering if I just got a "unknown" lower. It has one serious void in it which likely led to one of my broken drill bits, it had some notably hard and soft spots too. It finished out nicely enough in the end. I would recommend getting a quality aluminum lower from a reputable company.
 
Pinter, your probably right. I am really wondering if I just got a "unknown" lower. It has one serious void in it which likely led to one of my broken drill bits, it had some notably hard and soft spots too. It finished out nicely enough in the end. I would recommend getting a quality aluminum lower from a reputable company.

:what:

Yeah it would seem you got a bad one. If I found a large void in my "forged" lower while machining I would really start to wonder whether there were more in area's I hadn't removed.

FWIW, I've never ran across a void in a forged aluminum 80% lower.
 
Aluminum as jacked up with voids, inclusions, & hard spots as you've described is almost unheard of in developed nations; where'd this crazy piece of junk come from? Backyard casting project? It almost sounds as though this was a forging-plant reject that some budget maker churns into "80%'s" as a way of hiding these defects (metal defects are more common in bad forgings than rolling-mill billet stock)

Your lower sounds like the worst metal horror-story I've heard since half-melted bolts visible in a cut Chinese girder (though the radioactive waste dosed into Russian aluminum as sneaky disposal method was a close second). No worries about strength, it's undoubtedly still a sight better than the polymer lowers. The bigger issue long term is corrosion, since aluminum succumbs easily if very bad quality.

But there are 6061 lowers out there, and 6061 is pretty sticky compared to 2000 or 7000 series.
I'll bet 6061, since it sounds like quality was less than stellar here, I'd wager more corners were cut. Nasty, nasty metal to do cutting on (hate the 6000-series; loves to build up on and break lathe inserts), only worse stuff I've played with is 2024.

TCB
 
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