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View Full Version : agggh is my 80% useless?


tisguy409
09-17-2012, 8:12 PM
so I did an 80% lower build and ran into a problem milling. I cut away too much on the floor plate for the trigger, and now it's just an empty hole. Now there's no way to mount the trigger spring.

I installed the hammer and trigger without the trigger spring, and it seems to function well up until the point I try to test the reset. Obviously there's no force pushing the trigger forward anymore.

Is there any way to make the lower functional? I had the hammer spring installed backwards and it would reset properly, but would this cause problems firing?

Thanks guys!

Update:
I just reinstalled the safety selector and tried holding the trigger down and locking the hammer back, and it locks, but I need to manually push the trigger forward for the disconnector to release the hammer to the trigger. May be good enough... can it be better?

bloodhawke83
09-17-2012, 8:16 PM
Weld a plate in?

Sent from my DROID RAZR using Tapatalk 2

barbasol
09-17-2012, 8:20 PM
Plus one on the weld. A guy did this when I was milling my first. I'm pretty sure it was saved

bohoki
09-17-2012, 8:21 PM
put a little pin across to act like a floor for the spring legs i would probably use a threaded rod thread the holes and loctite it in then grind it flush

its neat now you got a drain


maybe you can bend a little thin piece of steel plate into a u shape flat bottom and have it stay in place with the hammer and trigger pins

apatomae
09-17-2012, 8:24 PM
Drive a thin roll pin through tiny drilled holes across the gap to support the spring. File the pin on both sides carefully till flush . Might have to mod bottom of trigger to clear. I' m no gunsmith but that's what I would do. Again I'm just throwing out suggestions

Intimid8tor
09-17-2012, 8:24 PM
Oh snap.

There are probably ways to fix it, but with that much I would destroy it and start over.

apatomae
09-17-2012, 8:25 PM
Will be a lot easier to clean now, just blast away

tisguy409
09-17-2012, 8:32 PM
thanks for the advice guys! i don't want to throw the lower away cuz i had the custom engraving work done to it (so no I have a sentimental attachment to it).

I want to find something I can sneak in between the floor plate and the back of the trigger that could naturally push it forward- like a spring- but it would definitely need some pressure to counter the hammer spring's tension.

Tripper
09-17-2012, 8:35 PM
I'm curious;
With the 80, cut as he suggests, is it considered a firearm yet?

tisguy409
09-17-2012, 8:37 PM
I'd consider it more like a 110% lower now.. extra metal missing =(

Chaos47
09-17-2012, 8:47 PM
I'd consider it more like a 110% lower now.. extra metal missing =(

That had me laughing so hard, lol thanks for that.

Sorry OP! GL

ramathorn
09-17-2012, 8:49 PM
Maybe you can use one of those upgrade "drop in" triggers that has the parts and spring enclosed in a housing. If you are going to upgrade your trigger in the future look into them now. May work.

dmcmillenfv
09-17-2012, 8:52 PM
Try bending the feet of the trigger spring down some, to get enough pressure to reset the trigger.

Thordo
09-17-2012, 8:52 PM
That's some pretty severe chatter. Did you do that on a drill press or a milling machine? You may have a bigger problem with the wall adjacent to the bolt catch slot. The pressure of the bolt slamming the catch may cause that to deform.

That's gonna be tough to weld. You could cut a plate at a thickness that replaces what you over cut, JB weld it in place, mold a JB weld wall to reinforce the wall mentioned above. Or, call it a loss and start over???

Thordo

sharxbyte
09-17-2012, 8:52 PM
That had me laughing so hard, lol thanks for that.

Sorry OP! GL

+1!

I second (third?) drilling another pin hole for the spring legs to sit on.

clay32
09-17-2012, 8:58 PM
Keep it in your bedside table drawer and when someone breaks in you can bludgeon them over the head with it.
Kidding aside, get in on another GB and cut a new one I say. It seems the 80% lowers all have something wrong after machining anyway, even if it's minor dimensions being off, but it looks like you did some irreparable damage to that bad boy.

bomb_on_bus
09-17-2012, 9:02 PM
What kind of set up did you use? And did you use the recommended jig with guide holes in place?

You could take the lower to a place that is set up for 80% lower mill work depending on where you are or how far you're willing to travel that is.

There are a couple of shops here in CA that are set up specifically for 80% lower finishing and that would be my first stop. Other than that see about JB weld and plug in place. Or like others have said a drop in trigger housing set. Like the Timney AR trigger group.

Jayruta
09-17-2012, 9:04 PM
Get a block of aluminum and mill it out into the hole shape .004 thicker than the hole and Press it into hole and re-mill it out. It can be fixed just have to figure out a way to smash material in the hole so it holds then remill it out.

SunriseF150
09-17-2012, 9:15 PM
I agree on welding a piece in that fits in the cut out shape. Like mentioned above, it might cause structural integrity to that wall? Timney or Wilson Combat or other drop in trigger would be your next option.

SunriseF150
09-17-2012, 9:17 PM
Oh and next time get the engraving done after you finish the milling.

Bug Splat
09-17-2012, 9:28 PM
I would dam up the bottom and fill it with Durafix then re mill the trigger hole. No welding machines needed for this stuff, check it out.....


2rH681CYDgw

wash
09-17-2012, 10:48 PM
That's some pretty severe chatter. Did you do that on a drill press or a milling machine? You may have a bigger problem with the wall adjacent to the bolt catch slot. The pressure of the bolt slamming the catch may cause that to deform.

That's gonna be tough to weld. You could cut a plate at a thickness that replaces what you over cut, JB weld it in place, mold a JB weld wall to reinforce the wall mentioned above. Or, call it a loss and start over???

Thordo
+1

The bottom of the FCG pocket is not really a high stress area.

A closely fitted plate and good application of epoxy should do the trick.

It's hard to see from the top but if you can cut a little shelf or notch so that the pistol grip holds the repair plate in place, that will reinforce the whole thing.

http://www.calguns.net/calgunforum/attachment.php?attachmentid=170018&d=1347941510

This is the reason why I strongly suggest CNC build parties.

Even though I have access to a Bridgeport style mill with DRO and I can borrow AR jig plates, I still spend the money to clamp it in at a CNC build party and press GO.

RECCE556
09-17-2012, 10:53 PM
Yeah, Sawsall that lower into three sections and start again. The missing portion is just one of several issues with that lower. You can always get another one engraved...but do it after you cut it (at a CNC party) and after you make sure it works...

Intimid8tor
09-18-2012, 7:02 AM
I'm curious;
With the 80, cut as he suggests, is it considered a firearm yet?

The first hole drilled makes it a firearm.

Intimid8tor
09-18-2012, 7:06 AM
I would dam up the bottom and fill it with Durafix then re mill the trigger hole. No welding machines needed for this stuff, check it out.....


2rH681CYDgw

I used alumaweld (like dura fix) to fill an oversized hole and remachined. It worked well. Damming it up will definitely be required in this case.

Other than that a trigger pack would probably work as well.

The Virus
09-18-2012, 7:14 AM
Jeesus, trash that POS get another 80% and do it right.
Were not talking about alot if money.
Yes it's useless

rkt88edmo
09-18-2012, 7:17 AM
JB Weld or paperweight.

tisguy409
09-18-2012, 7:17 AM
Thanks guys. I'll probably DROS a new lower or wait for another build party and go that route. Maybe I'll get a drop in trigger to make it shootable- if the lower gets deformed/destroyed at least it dies serving its purpose and I'll keep it as a souvenir.

The depths were done with a drill press, then milled. My friend had ordered a small mill that literally blew its motor working its way on my lower. After he got a new mill, we milled without knowing the full controls of it and well... s* happened. Since the floor was milled out we just decided to clean it up and see if the FCG would still function.

I'll test it at the range this week manually resetting the trigger, but the CMC trigger looks like a reasonable option.

rkt88edmo
09-18-2012, 7:19 AM
+1

This is the reason why I strongly suggest CNC build parties.

Even though I have access to a Bridgeport style mill with DRO and I can borrow AR jig plates, I still spend the money to clamp it in at a CNC build party and press GO.

CNC build and go is cool, and I'm not knocking it - but it isn't the same kind of fun as a mujahadeen buildout! I love seeing lowers finished with nothing but a hand drill - great! They won't be as pretty or straight and true but they an be functional and you did it with a fairly low amount of tech.

P.Charm
09-18-2012, 7:32 AM
I would just call it an $80 lesson and start over.

hnoppenberger
09-18-2012, 7:37 AM
that looks like hammer'd **** man. cnc party for sure next time

sonnyt650
09-18-2012, 7:49 AM
As they say "you gotta know when to fold 'em" -- it's in a better place, let it go. It hurts a bit but you can do serious damage to your wallet trying to fix it.

That's not an opinion with no experience behind it: I finished up a couple of those 80% 10/22 receivers and on both couldn't get the barrel hole located and square to the shoulder that the bull barrel sits flush against. I spent a fair amount of money for tooling to cut the barrel hole on a mini-lathe rather than use the drill press jig (bought a drill press too), still don't have a solid way of mounting it so I only finished one and it's not pretty at that. The other one is going to sit under my desk until I decide to spring for real machine tools or time at some shop on a full-size lathe.

ouch1
09-18-2012, 10:17 AM
Get a block of aluminum and mill it out into the hole shape .004 thicker than the hole and Press it into hole and re-mill it out. It can be fixed just have to figure out a way to smash material in the hole so it holds then remill it out.
^ +1, but rather than pressing the plug into the hole just freeze the crap out of it, and warm up the lower to about 120F. The plug will just slide in.

Another thing to think about is to drill a couple holes through the lower part of the plug and receiver and drift some small pins in place with locktite. It will be very solid then.

-ouch1

BTW the quick way to freeze the plug is ti use something like this: http://www.google.com/products/catalog?q=freeze+spray&hl=en&prmd=imvns&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.&biw=1680&bih=878&um=1&ie=UTF-8&tbm=shop&cid=11041911730662588269&sa=X&ei=RrtYUIzqO4X2iQKLg4G4Bw&ved=0CI4BEPMCMAU

The Virus
09-18-2012, 11:00 AM
Yes, spend more time and money polishing a turd....

tisguy409
09-18-2012, 11:31 AM
Yes, spend more time and money polishing a turd....

Thanks for the optimistic comment, much appreciated. :rolleyes:

The Virus
09-18-2012, 11:47 AM
Thanks for the optimistic comment, much appreciated. :rolleyes:

Hey man, just keeping it real.

tisguy409
09-18-2012, 12:05 PM
Hey man, just keeping it real.

haha I know, but you don't have to crush the little bit of hope I have :p.

If anything this will be a "learning" process.

MrPlink
09-18-2012, 12:15 PM
Yes, spend more time and money polishing a turd....

I see God did not curse you with drive or ingenuity.

P.Charm
09-18-2012, 12:19 PM
I see God did not curse you with drive or ingenuity.

I think it's more of a cost thing. just spend the 100 and try again. 100 is a drop in the bucket to what comes after the lower is done.

I say buy another one (i see it's anodized already) and go to a CNC build party.

jsipe007
09-18-2012, 1:07 PM
I feel for ya man, but hey! If there was anything you didnt like before about the custom engraving, now is the time you can fix it and make it perfect!

Good luck with the next build!

foxtrotuniformlima
09-18-2012, 1:17 PM
I think that a CMC drop in will solve the problem. The thing is that the cost for one is $ 160 or so. Unless that was the way you were going, I'd say start over or try the JB Weld / dura fix if only for the fun .

P.Charm
09-18-2012, 1:22 PM
i guess if you do go about fixing it, it will give your rifle character.

The Virus
09-18-2012, 2:05 PM
I see God did not curse you with drive or ingenuity.

Just common sense

MrPlink
09-18-2012, 2:50 PM
Just common sense

common sense should tell you this is not load bearing portion and that it would function just fine with a simple patch job that could be performed rather easily by ALMOST anybody with a just a little creativity and elbow grease.

If you are smart about it it could also be done so that nobody would ever know, not even internet experts like yourself.

wash
09-18-2012, 3:14 PM
CNC build and go is cool, and I'm not knocking it - but it isn't the same kind of fun as a mujahadeen buildout! I love seeing lowers finished with nothing but a hand drill - great! They won't be as pretty or straight and true but they an be functional and you did it with a fairly low amount of tech.
I'm not sure I would spring for custom engraving for a Khyber Pass style build.

In fact I would choose an AK for a Khyber Pass style build or maybe a MAC.

I get your point but when you contrast how nice a CNC homebuilt AR can be with how badly a drill press homebuilt AR can go, drill press doesn't make much sense.

rkt88edmo
09-18-2012, 4:45 PM
C'mon now - you can say a Khyber Pass style build is DIY - a CNC'd build is pretty much a commercial lower with a few advantages of not coming from a commercial factory, but there is no DIY aspect to it - they are wholly different animals.

I will continue to insist that DIY makes sense!


I'm not sure I would spring for custom engraving for a Khyber Pass style build.

In fact I would choose an AK for a Khyber Pass style build or maybe a MAC.

I get your point but when you contrast how nice a CNC homebuilt AR can be with how badly a drill press homebuilt AR can go, drill press doesn't make much sense.

MrPlink
09-18-2012, 5:29 PM
I began a drill press build a couple years back. I ended up just milling it (not cnc).
If you have LOADS of time, no reason at all it couldnt come out nice.
Hell, somebody once posted a lower they did with nothing but hand tools.

6mmintl
09-18-2012, 6:21 PM
Id hate to see what you could do with a dremel tool.

You could weld it up with a bottom plate.

edwardjames
09-18-2012, 6:28 PM
I would dam up the bottom and fill it with Durafix then re mill the trigger hole. No welding machines needed for this stuff, check it out.....


2rH681CYDgw


woah:eek:! that stuff is impressive. from what i just saw that might be a good idea to try this method!

The Virus
09-18-2012, 6:32 PM
common sense should tell you this is not load bearing portion and that it would function just fine with a simple patch job that could be performed rather easily by ALMOST anybody with a just a little creativity and elbow grease.

If you are smart about it it could also be done so that nobody would ever know, not even internet experts like yourself.

Umm , ok buddy.
whatever you say.

wash
09-18-2012, 6:34 PM
C'mon now - you can say a Khyber Pass style build is DIY - a CNC'd build is pretty much a commercial lower with a few advantages of not coming from a commercial factory, but there is no DIY aspect to it - they are wholly different animals.

I will continue to insist that DIY makes sense!
I disagree, it's just DIY with better tools.

Here is one I did along with DIY laser etching:

http://www.calguns.net/calgunforum/attachment.php?attachmentid=160322&stc=1&d=1342909871

http://www.calguns.net/calgunforum/attachment.php?attachmentid=160323&stc=1&d=1342909880

Fitting an Arredondo mag well to a QD billet 80% lower is quite a bit of DIY too.

jbk
09-18-2012, 6:38 PM
If your Going to go the weld route, you need to figure out what kind of aluminum it's made of. I just built 80s and they were made of 70 series. If so they can't be welded by normal means. If you can get it to take the weld it will crack on weld or next to it easy. Your probably better off to start over.