80% lower help. Knox/Blount area

[jaxjohn419]

I run www.facebook.com/2ndAmendmentUSA. I have @44000 followers and decided to do a video project on an AR build for everyone.

I got all of the parts donated and started the build. 

Well, I had some help from a friend who has a press and jig. The drilling fine, until I started milling out the lower. My friend was out of town for that part and I f'ed up.

I made a small mistake and blew out there bottom where the trigger hole would be. 

Taking it to a gun show, a couple of people thought that I could finish it off and then use an epoxy in the bottom, and then drill it out. 

This is WAY above my level and I was looking for someone in this area who might be able to help. My video will now be on what to do in a similar AR build situation.

 

Thanks in advance.

[gjohnsoniv]

My first thought would be to weld it back up. Some one more knowledgeable might chime in and say don't do what I'm thinking though.

If you have access to a welder and the correct filler I think it could be plugged up and re-milled. See if you can a chunk of copper that can fit in the trigger guard that's flat. Clamp that in some way and weld from the top. Mill out what you trying to do originally. Or see about finding a piece to stick in to fill the hole and weld around that. Those are just my initial thoughts, hopefully some of the smiths will have a different method. I too would like to know what to do in a similar situation.

[Dolomite_supafly]

Never, ever try to hold something by hand while trying to mill something out. And ALWAYS have the speed up very, very high.

 

With that being said it will cost you more to fix that one than it will cost to buy a new 80% lower.

[Omega]

Never, ever try to hold something by hand while trying to mill something out. And ALWAYS have the speed up very, very high.

 

With that being said it will cost you more to fix that one than it will cost to buy a new 80% lower.

Maybe not, I used some low temp aluminum solder on a few other things and it may just work:  Not sure of availability, but I found some rods at my local hardware store many vids out there here is one:  http://www.youtube.com/watch?v=aiThO-UQIWE

[jaxjohn419]

not holding it in my hand, but didn't bolt down completely. 

as far as what some of the gun people at the gunshow told me, i should finish milling and then use epoxy (http://www.brownells.com/gunsmith-tools-supplies/stock-work-finishing/stock-bedding-adhesives/epoxy-metals-prod5808.aspx) to fill in the hole and then finish. It's just a little above my skill level though, and I was wanting some assistance.

[jaxjohn419]

the pressures on that trigger hole are apparently low enough to allow this type of fix

[jaxjohn419]

oh, no access to a welder.

[Raoul]

I always trust what people at gun shows tell me.

[jaxjohn419]

what i neglected to say was that this lower was donated and even has an engraving on it for my page

[URL=http://s771.photobucket.com/user/jaxjohn419/media/IMG_0944_zpsde7824e2.jpg.html][/URL]
 

[jaxjohn419]

I always trust what people at gun shows tell me.

I hear what you are saying, but I am talking about the vendors. I spoke with people who were gunsmiths from other parts of the state.

[peejman]

Ouch.

 

Welding it would be my first choice, and I know a couple local welders who could do it.  It might need to be re-heat treated after welding to ensure strength.  That likely would require stripping the finish.  I'll have to look up the temp for the heat treatment to see if that would kill the finish. 

 

There are structural epoxies available that work well with aluminum and applying them is pretty simple.  We do it all the time at work (I fix jet engine parts for a living).   You'd need to blast the area to remove the finish so the epoxy will stick.  Then you basically just mix the stuff, glob it in there, cure it (typically heat cure), and then machine it back to final dimensions.

 

That said, fixing it will cost more than just replacing it.  But since is a special one, you might not have a choice. 

Talk to Mike at Lawenforcementsalestn here... He's got the machine capability to do the work properly and he's in Oak Ridge.  Getting another lower and having him re-do the engraving and the machine work might be the best option.  Or if you just want to fix it, that's fine too. 

[raildog]

Let start by saying im a machinist/welder for a living you can tig or hile arc weld the hole up it would be slow and tedious it will kill the finish most shops in the Nashville area will charge $65 to $100 a hour to do the job and it will take a lot longer than a hour just my two cents good luck

[Clod Stomper]

Ouch.

Welding it would be my first choice, and I know a couple local welders who could do it. It might need to be re-heat treated after welding to ensure strength. That likely would require stripping the finish. I'll have to look up the temp for the heat treatment to see if that would kill the finish.

There are structural epoxies available that work well with aluminum and applying them is pretty simple. We do it all the time at work (I fix jet engine parts for a living). You'd need to blast the area to remove the finish so the epoxy will stick. Then you basically just mix the stuff, glob it in there, cure it (typically heat cure), and then machine it back to final dimensions.

That said, fixing it will cost more than just replacing it. But since is a special one, you might not have a choice.

Talk to Mike at Lawenforcementsalestn here... He's got the machine capability to do the work properly and he's in Oak Ridge. Getting another lower and having him re-do the engraving and the machine work might be the best option. Or if you just want to fix it, that's fine too.

Mike could definitely fix it. But he may have to serialize it and add it to his records.

I have used epoxy to fix misdrilled pin holes before. It held up fine.

Were it me, I wouldn't have an issue with it. But I probably wouldn't use it to defend my life, either.

[jaxjohn419]

thanks for the advice guys. I think I am going to try that aluminum epoxy that Brownells has. I heard that is good stuff. 

[peejman]

thanks for the advice guys. I think I am going to try that aluminum epoxy that Brownells has. I heard that is good stuff. 

 

 

Prep work is key.  Note that you'll have to remove the finish all around the area so the epoxy will adhere properly.  Rinse it thoroughly with acetone and handle it only with rubber gloves after you remove the finish. It also states to use fiberglass to bridge "large holes"... I'd say yours qualifies as large.  I'd also do the heat cure. 

 

http://www.devcon.com/prodfiles/pdfs/fam_tds_107.pdf

[MacGyver]

You'd definitely benefit from buying an actual end mill as opposed to trying to do it with a drill bit.

[LawEnforcementSalesTN]

Raildog nailed it!

 

Welding aluminum is a real BEOTCH by itself.  Welding an AR receiver is a true Mother *&(*&((* ;o) ... You can stick a lighter to the side of an AR reciever for 5 minutes it seems and that puppy will pull to the side a few thousandths ... it's not hard at all to jack one up in a heartbeat.

 

It could be repaired by those more skillful than me (I am not a welder by any stretch) but due to the aluminum and heat disbursment it would be a tidius job .. family heirloom maybe but short of a $25K registered receiver M16 I wouldn't worry about that level of correction.  I do have a buddy who helps me who can weld on water ...  he can fix it but you're definitely then looking at a refinish, cleanup, etc.

 

Back when John Norell (infamous C2 from the 70s/80s) did a lot of demil jobs (old M16 receivers cut in half), he used all kind of jigs to hold things together .. aluminum shrinks too so he had to compensate for heat and shrinkange .. a true master when you look at his work...but none of that really applies here as you're hole isn't in a location I'd be that concern with.

 

If it were me, I'd just mill the area a bit to clean it up and make it looks as nice as it could - as if it were meant to be ... there's nothing underneath that needs the hole filled up other than your pride ;o) .. the trigger will pivot on its horizontal pin .. so short of the aesthetic attributes, it won't hurt anything to remain.

 

If you're going to do this in the future, you can get pretty decent results using a mill bit in a drill press WITH a milling vise.... the kind with the X-Y axis handles... you can get an adeuate one on ebay for $50-$60...drilling lifting, moving over, drilling .. it's going to look choppy and that's a very nice receiver blank you have there.

 

But looks is all you hurt... as other have suggested you could epoxy something, cut a small piece of aluminum and put it inside to cover, options are endless...   I'll be happy to help you clean it up a bit unless you want to remain loyal to the post and use only common tools someone would have lying around.  I can cheat a bit with the equipment I have lying around ;o)

 

Best of luck though.. I'll be around next week if you wanted to drive down and let me take a closer look...happy to do so...  but seriously, if you had to go and blow a hole somewhere, you nailed the best sacrificial spot ;o) 

Edited February 13, 2015 by LawEnforcementSalesTN

[jaxjohn419]

Raildog nailed it!

 

Welding aluminum is a real BEOTCH by itself.  Welding an AR receiver is a true Mother *&(*&((* ;o) ... You can stick a lighter to the side of an AR reciever for 5 minutes it seems and that puppy will pull to the side a few thousandths ... it's not hard at all to jack one up in a heartbeat.

 

It could be repaired by those more skillful than me (I am not a welder by any stretch) but due to the aluminum and heat disbursment it would be a tidius job .. family heirloom maybe but short of a $25K registered receiver M16 I wouldn't worry about that level of correction.  I do have a buddy who helps me who can weld on water ...  he can fix it but you're definitely then looking at a refinish, cleanup, etc.

 

Back when John Norell (infamous C2 from the 70s/80s) did a lot of demil jobs (old M16 receivers cut in half), he used all kind of jigs to hold things together .. aluminum shrinks too so he had to compensate for heat and shrinkange .. a true master when you look at his work...but none of that really applies here as you're hole isn't in a location I'd be that concern with.

 

If it were me, I'd just mill the area a bit to clean it up and make it looks as nice as it could - as if it were meant to be ... there's nothing underneath that needs the hole filled up other than your pride ;o) .. the trigger will pivot on its horizontal pin .. so short of the aesthetic attributes, it won't hurt anything to remain.

 

If you're going to do this in the future, you can get pretty decent results using a mill bit in a drill press WITH a milling vise.... the kind with the X-Y axis handles... you can get an adeuate one on ebay for $50-$60...drilling lifting, moving over, drilling .. it's going to look choppy and that's a very nice receiver blank you have there.

 

But looks is all you hurt... as other have suggested you could epoxy something, cut a small piece of aluminum and put it inside to cover, options are endless...   I'll be happy to help you clean it up a bit unless you want to remain loyal to the post and use only common tools someone would have lying around.  I can cheat a bit with the equipment I have lying around ;o)

 

Best of luck though.. I'll be around next week if you wanted to drive down and let me take a closer look...happy to do so...  but seriously, if you had to go and blow a hole somewhere, you nailed the best sacrificial spot ;o) 

 

I would absplutely appreciate the help. can I shoot you a PM? 

[LawEnforcementSalesTN]

I would absplutely appreciate the help. can I shoot you a PM? 

 

sure man

[van37725]

If it's 7075 T6 aluminum Don't try to weld it.  If it's 6061 OK.

 

Van