BoBro Mount: Need advice Extracting a Broken Screw

[DMK]

I have a BoBro Aimpoint 30mm ring mount that I'm using on my X95. The base is held on by two fairly large Torx screws. I wanted to flip the base to put the QD lever on the opposite side so I didn't scrape my knuckles when racking the charging handle. Apparently, they use red Locktite on those screws. The first screw popped free no problem. The second one immediately snapped right at the head of the screw.

I have an easy-out, but I'm concerned about that red locktite. If it snapped the screw, what are my chances the easy out will work?

I figured I'd ask for advice before I make any attempts and potentially make it worse.

Thoughts? Advice?

[Smoke & Recoil]

If there is any screw shank exposed, you could slot it and use a flat head screw
driver and also apply a little heat to the screw, the heat will soften the loctite.

[DMK]

If there is any screw shank exposed, you could slot it and use a flat head screw
driver and also apply a little heat to the screw, the heat will soften the loctite.

I think I'd rather drill the center and use the easy-out rather than try to slot it. The reverse threaded cone will dig in and apply more torque than a screwdriver blade.

Someone mentioned to me that using a soldering iron to heat up the screw might loosen the Locktite, so I think I'll try that. I'll warm up the easy-out too so it doesn't act as a heat sink.

[Smoke & Recoil]

Perhaps you can post a picture of the screw in question to give a little more insight of the problem ?

[BornFighting88]

I’ve never had good luck slotting them for a flat blade. I always end up boogering the slot, too. One step forward, three steps back for me.

I have one of those easy outs, and it saved my bacon when a broken off screw in an action. Also had loc-tite, but the blue goo. Easy break stuff.

I would second the soldering iron to dump a little heat to get the red glue tacky, and then backing it out with the easy-out. Be firm but gentle. Once you get that puppy out, if you can get your hands on the tap for the thread, run that in it gently to make sure you got all the crap out. Spiral flute, if you can get your hands on one. That will bring the debris up and out of the hole, not compact it at the bottom like some taps will.

Sounds to me like that particular screw had a weak point that finally fatigued and failed and sheared off.

[DMK]

Sounds to me like that particular screw had a weak point that finally fatigued and failed and sheared off.

Yeah, I'm wondering if that screw was defective or possibly over torqued at the factory.

[Pahoo]

I think I'd rather drill the center and use the easy-out rather than try to slot it. The reverse threaded cone will dig in and apply more torque than a screwdriver blade. Someone mentioned to me that using a soldering iron to heat up the screw might loosen the Loctite, so I think I'll try that. I'll warm up the easy-out too so it doesn't act as a heat sink.

I have used this method with good results. The first hurdle, will be to make sure your drill is centered. Did the first hole, show signs of lock-tite? This can get tricky and slow and easy wins this race !!! .....

There have been occasions where I had to drill all the way through add heat. this will weaken the screw body and relieve the fit. Not easy and I wish you success .....

Be Safe !!!!

[Scorch]

Drill it, heat it until the LocTite smokes, then use your EZ-Out.

[Nathan]

I wonder if they would do it for you, if it is off the gun….

[HiBC]

Screws typically break off to leave an uneven surface. Its very difficult to get a drill to start just where you want it on the end of a broken off screw.

The true running rigid spindle ,precise x and y positioning and rigid vise make a mill the ideal tool for the job.

But a drill press can do the job.

Do very carefully position/secure the workpiece in a vise under the spindle.

Now what you need is a small center drill. What might be called a "combined drill countersink" in the tool catalogue.

The original purpose is to drill those nice center holes you often see in the end of a shaft. The lathe tailstock center rides in those. Tts common practice to use a center drill to locate a precise starting point for a twist drill.

Use a center drill to create a "start" for your drill. They are short and rigid and they don't wander off. Get the center drill pilot started then some of the 60 deg countersink. Now you can start your drill.

One trick that sometimes works is a left handed drill. Its ground to cut in the counterclockwise direction. Generally as a drill breaks through it will catch and grab on the workpiece, and the stub of the broken screw will be heated b the friction of drilling. The left hand drill generally backs the screw right out.

Some EZ outs look like a left handed licorice twist. Some are just a tapered square with a groove for some "hook" at the corners. I've had the most success with the square type. I grind my own out of a lathe tool bit and use a tap wrench.

I'll throw in a bonus trick. Suppose you are changing the car's thermostat and break off a bolt. Pretty hard to start a hand drill in the center of a broken off bolt under the hood.
But if you look at it just right,that thermostat housing will do for a drill jig.
You just need a bushing that will just fit in the hole the broken bolt goes through. Its OK if it fits with a tap of a hammer. The hole through the bushing needs to just barely let the drill pass through. You can drill the hole with the drill bit size you are going to use to do the job.

Now,use the unbroke bolt to hold the thermostat housing in place, eyeball center it the best you can, tighten the bolt and at least you are hand drilling with a drill jig and drill bushing. It will probably work.

Beware a cast aluminum part will often be fitted with a helicoil or Threadzert
I'm not sure how that will affect the job, but keep your eyes open.
You may end up replacing a helicoil

[eflyguy]

If you didn't apply heat it's not surprising it broke off. Red is intended to be semi-permanent and takes a lot of heat to soften. It's recommended for blue as well, but not as much heat is needed.

I would seek out a left-handed drill bit first, and do this in a press with the receiver blocked up and stable.

If you're not equipped, you might consider asking a local smithy.

[DMK]

Update:

I clamped the mount in my vice with wood blocks protecting/insulating it.

The screw had broken off fairly flat, so I was able to center punch it and drill a centered pilot hole all the way through the screw. Then I drilled a slightly larger hole until I could get the Easy Out in. The Easy Out got a good bite, but the screw would not budge. I took a soldering iron, stuck it in the hole and let it get hot enough that it was too hot to touch the mount. Still would not budge.

After a couple of tries, I was afraid that I'd break the Easy Out, so I finally just drilled it out one size larger and tapped it to 10-32. Luckily, I had a 10-32 screw on hand that fit perfectly. I actually replaced both screws with stainless steel phillips head. I used blue Loctite and a Fatwrench to torque both to 25 inch lbs.

I didn't drill the other one out, so they are mismatched in size, but they are at the bottom of the mount where you can't see them anyway. I figured quit while I'm ahead and it's just a minor cosmetic issue.

So, this didn't exactly go as planned, but since a replacement mount is $175, I guess I did OK. It's back together, secure, and will work just fine.

Thanks for the help everyone!

[BornFighting88]

Glad you were able to fix it. Only other thing you COULD have done was drill it out like you did and get the heli-coil for the threads of the original. May be too small to even heli-coil like that.

But glad you got it fixed. Custom fixes add a personal flair to your gear.

[Unclenick]

You may have needed to heat it from the underside. If you read the instructions on high strength (Red) Loctite, it requires 500°F heat applied for 5 minutes to release it.