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Posted: 8/1/2016 9:54:01 AM EDT
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I done goofed Gents, That being said since ive crossthreaded the receiver what would be the best course of action? Ive got a tap and die set, it probably wouldn't be too hard to set some new threads in there. Has anyone else made this mistake? If so, how did you correct it?
Edit: I could also run that screw down with an impact since I have no intentions of changing the BCM grip I had planned on putting on, I also have no plans to ever sell the rifle. |
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I agree with trying the tap first. Short of that working your best bet to properly fix it would be to put in a helicoil repair. These can work very well, but require proper drilling out of the hole. Without the right set-up and prep you are asking for trouble, IMO.
I cant imagine you would have any luck "jamming" the bolt into permanent place. |
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Quoted:
I agree with trying the tap first. Short of that working your best bet to properly fix it would be to put in a helicoil repair. These can work very well, but require proper drilling out of the hole. Without the right set-up and prep you are asking for trouble, IMO. I cant imagine you would have any luck "jamming" the bolt into permanent place. Ive heard of these helicoil things but don't have any experience with them, If the tap doesn't work im just gonna impact it on down to where it wont come off. its a cheap Rguns lower, I may end up just swaping it out for an Anderson or something. I don't know yet though. |
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Run a regular threaded bolt through from the inside of the receiver to chase out the threads. Presuming you don't have a crappy lower that's not threaded all the way through.
This is why I strongly recommend that people throw away the "milspec" grip screws and use hex head screws with a T handle hex driver. Also helps a lot if you know the proper technique to back up and find the start of threads, which applies to any threaded fastener. |
| Im gonna have another go at it this weekend, (my rifles don't get to stay with me due to living in the barracks) I know for a fact that the lower isn't treaded all the way through, its an RGuns lower that was kinda rough but I expected that because it was 50 bucks OTD. I ease the tap first and see if I can get some desirable product, if that fails its getting swapped with an Anderson and my machinist buddy can have a go at it. its kind of a win win, it gives me a reason to buy another lower lol. I was using a t handle hex when putting it on, I eased in and it was feeling tighter than usual, I turned it another quarter of a turn thinking it might have just been some grit in the threads, I backed it out after that and out came some threads with it. the screw was fine but the threads where mangled. |
| Ok you need to learn the technique to back up screws then. Turn them backwards slowly, and you'll feel the click when the threads are properly engaged, then start turning forward. Go 2 or 3 revolutions slowly backwards if needed and make sure the click is at the same spot each time. |
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How deep is the 'screwed up thread' area? By correctly tapping with the correct tap, you should be able to clean up, or just remove, the screwed up threads. Then simply use a longer screw to reach the good threads deeper in the hole. You mentioned that the hole /threads do not go all the way thru - this can be fixed at the same time. No need to junk it, nor do you need to 'marine' it.  |
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It's Aluminum and it is easy to cross thread it .
The screw is pretty long and it is usually just the first little bit that gets messed up so running a tap (1/4-28) up it will straighten it out and although the start will be loose and sloppy there will be plenty of material to hold things together. Take your time with the tap and everything will likely be cool |
| As mentioned, I would use the correct tap for the grip, ¼x28, and go slowly while backing out every few turns. If the tap felt loose when fully engaged(meaning the hole has broken threads and is fuked), I would use a helicoil repair coil to create an even more secure ¼x28 hole. It's easy and if you haven't done it, check some YouTube videos. It will cost like $10-15 for everything and you'll have piece of mind. That's just me. |
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Yep, 1/4-28TPI tap from the top downward to see if you can clean the threads to begin with.
If this is a no-go and the threads are toasted instead, the Hexicoil is the solution instead. Here, the tap kit will come with a drill bit to slightly over size the channel, then it's tape threaded to accept the Hexicoil insert, which it inside ID threads are 1/4-28tpi instead. http://www.walmart.com/ip/Helicoil-Kit-1-4-28/19655135?wmlspartner=wlpa&selectedSellerId=51&adid=22222222227016766526&wmlspartner=wmtlabs&wl0=&wl1=g&wl2=c&wl3=51753059951&wl4=pla-67800182224&wl5=9028718&wl6=&wl7=&wl8=&wl9=pla&wl10=100362769&wl11=online&wl12=19655135&wl13=&veh=sem 
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since when? can you document that, or is it lore? Quoted:
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Over the counter taps are oversized, so don't tap the hole any further than necessary to clean the threads up. That's what I would like to know as well, I'm a HE mech and all of my taps seem to be the correct size when ever Ive had to use them |
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No, I am thinking of all the times I have tapped factory holes, even just to clean them out, and the hardware store taps usually remove some metal. Run one through a nut and see if it does not cut.
The hardware store class fit, as I recall, is a looser tolerance than what factories or production uses. If anybody has a regular tap, bought over the counter from a hardware store, and can run it all the way in the grip screw hole without cutting into the factory threads, I will be amazed. |
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Standard taps are the correct sized, and you are either yaw'g the tap by hand cranking to cause the channel to be over sized, or you have run-out in the machine tool holder that your using to tap the channel or the the Z axis has not been trammed correctly, which will cause the same problem as well.
Hence if you want to tap true, then you pretty much need to run the tap in a mill with a collect in the spindle, so the tap is running true to the drilled channel, without any run out in the tap as it threading the channel. |
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