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jbultman

Stripped screw on red dot mount?

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Posted (edited)

I just bought a open gun and when I was removing the optic/red dot mount from the frame to replace it I realized that it had a stripped screw hole on frame of the gun and was only using 4 screws instead of 5. I was going to use a gogun thumb rest and need all 5 holes.

Any suggestions on how to fix?

thanks

J

Edited by jbultman

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Posted (edited)

If you have access to a drill press I’d try to drill off the head of the stripped screw. Then use a pair of needle nose vice grips to remove the rest of it. 

 

Or just use 2 screw holes for the gogun thumbrest. 

Edited by McGunner

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Posted (edited)
4 minutes ago, McGunner said:

If you have access to a drill press I’d try to drill off the head of the stripped screw. Then use a pair of needle nose vice grips to remove the rest of it. 

I’ve got the screw out of the mount and frame. The screw came out easy, just not fully able to tighten the screw to the new mount. The issue is what would I do next to put the new mount on...

Retap with same thread?

Helicoil?

Enlarge and retap with a larger hole?

Deal with and use 4 holes?

Thread in new screw and red locktite  and not tighten down all the way?

thanks

Edited by jbultman

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You could try to retap (I’m guessing it’s the standard 5-40) and use the red locktite. See if you can get it snug. If the threads are totally shot you’d have to go up a screw size to 6-40.

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Posted (edited)
27 minutes ago, McGunner said:

You could try to retap (I’m guessing it’s the standard 5-40) and use the red locktite. See if you can get it snug. If the threads are totally shot you’d have to go up a screw size to 6-40.

Nope, It’s already a 6-40. But I’ll give that a go 

if it doesn’t work, would a 8-40 be too large?

Edited by jbultman

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Fill it in with JB weld, let dry, drill and tap.

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Hello: Weld it up and redrill and tap it in a milling machine. Not sure why it is 6-40 already? Thanks, Eric

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16 minutes ago, Aircooled6racer said:

Hello: Weld it up and redrill and tap it in a milling machine. Not sure why it is 6-40 already? Thanks, Eric

Thanks.  Not sure why either. 

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I would not use JB weld. Ain’t gonna last

 

I would not weld it up and try to drill and tap. A weld is super hard and you will have a heck of a time doing that. Even with a mill and high end carbide bits and taps. 

 

Best bet, if there is enough material, drill and tap to the next size up. 

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I would try the epoxy and drill and tap. Epoxies today are really good. Worse case your back to square one, with no damage. Don’t know if heli coils go that small, but that has to be done perfect. Going up one size would rely on the spacing of the screws, so the heads might touch, or not even be feasible because of spacing. Welding up is possible but you better know what your doing. Could warp frame, filler weld is hard and drill might walk if not done perfect.

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I put 5-40 holes in my guns so if this happens I can punch it out to 6-40.  Since you're already at 6-40 I'd helicoil it.  It's a little expensive to get all the tools, but it's a legit repair that works well.  I also think punching it out to 8-36 is a workable option.  

 

The issue with helicoil will be locking the screw as you don't want to use loctite.  However, you can get a distorted helicoil in 6-40 to be your locking mechanism.

 

If you have material to punch to 8-36 you can loctite like usual.

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On 8/11/2019 at 2:06 PM, jpm2953 said:

I would not weld it up and try to drill and tap. A weld is super hard and you will have a heck of a time doing that. Even with a mill and high end carbide bits and taps.

 

Not always the case.  You can get welding wire that produces quite soft welds.  That type is used often for medical equipment.

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Hello: I have welded up 6 STI 2011 frames that had stripped threads on them. No problem drilling and tapping them if you use the correct filler rod. As a note I was a Tool and Die maker in a past life. Thanks, Eric

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