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Old 15-05-10, 10:37 AM   #1
gvinrad
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Cool Removing a broken screw or bolt from a blind hole

Hi Guy's,

Have you ever tried to get a broken screw out from a blind hole, I have had limited success with easyouts in fact I have found them to be anything but.

However by far the most successful way I have found is to start drilling them out with a lefthanded drill bit, most of the time the drill will bite into the screw and just wind it out. You do need to use a reversable drill though, it may also have been neccesary to soak or heat the screw first before drilling.

If it's a lefthand thread then you can use a normal drill bit (righthanded) with the drill running in the forward direction, I used this technique to remove a broken screw from a dynamo armature held in my lathe which had a left hand thread to good effect.

I have a few lefthand drill bits left from my days using a Britan lathe, although I have found them still available on the net if you google it.

Cheers, Gerry
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Old 16-05-10, 02:17 PM   #2
sidevalve
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Nice idea but my problem has always been trying to get the drill to stay anywhere near central. All depends on the size of screw and if you can get a punch into the remains. Worth a try though.
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Old 16-05-10, 02:49 PM   #3
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Default Drilling bolts.

You should always use a centre guide. A piece of bar at least 1" thick with a hole the size of the drill You are using and have it firmly clamped to the workpiece with the hole lined up with the bolt, and plenty of cutting compound. I'll agree with You on the "Easyouts". The taper makes the bolt swell and defeats the object, unless you use a skinny one then it snaps!!
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Old 16-05-10, 08:50 PM   #4
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At work we used to have an extractor set made by Blue Point (part of Snap On), they were parallel but with flutes that cut a groove into the stud etc and therefore didn't expand it. The set came with drilling guides as well so that drilling dead centre wasn't a problem, never had a failure with it BUT it must have been a very expensive set to buy!

Pete.
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Old 17-05-10, 02:46 AM   #5
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Default Tools.

As with every thing else in life :- "Yer pays yer money" especially where tools are concerned!! Buy quality tools and they'll do the job they're supposed to do and last a lifetime. I bought a "Deck & Blacker" 18v battery drill recently from a reputable DIY store and the bits supplied with it were a joke. I think that they were made out of plastic sprayed silver. The screwdriver bits were the same, they're all in the scrap bucket now!!! You can't buy real quality tools without spending a lot but it's worth it in the end. I still have a set of "Bedford-Vanadium" spanners, which were "expensive" in the late 60's when I bough them and they are still in excellent condition, also a set of American "Armstrong" spanners ( the ones that came in the crates with the "Packard-Built" Merlins during the war) and they are the same. Real quality gear made to last.
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Old 17-05-10, 08:57 AM   #6
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In an ideal world a centre guide is a great plan if you can do it, sadly some broken off bolts aint that helpfull and will usually be somewhere almost impossible to either A- get at or B- accurately clamp something to. In some cases it may be as easy [OK not cyl heads etc] to drill and tap another hole.
Ah,don't yer just love rust, sticks metal to metal better that welding.
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Old 11-08-12, 09:08 PM   #7
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I recently got a bleed screw out of a fuel pump body by drilling a hole then grinding up a micro square drift, tapped it in and used a tap wrench to loosen the thing up and work it out.
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Old 11-08-12, 09:28 PM   #8
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Quote:
Originally Posted by Windrush View Post
At work we used to have an extractor set made by Blue Point (part of Snap On), they were parallel but with flutes that cut a groove into the stud etc and therefore didn't expand it. The set came with drilling guides as well so that drilling dead centre wasn't a problem, never had a failure with it BUT it must have been a very expensive set to buy!

Pete.
These are the best.
Left hand drill bits are a joke. Once the bolt is so stuck that it breaks off in the frist place, you can forget using a left hand drill. They invariably break and then you are worse off, because they are virtually impossible to drill out.

If the peace of bolt is not really stuck, the easiest way is to use a welding apparatus to stick a rod on the bolt end.

Hubert
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Old 11-08-12, 10:01 PM   #9
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Could have done with you guys today... Been getting a stud out of our new fergie head, it had snapped off flush. Tried welding a nut to it 3 or 4 times, but no luck, so tried drilling it out, but the heat of welding had hardened the stud, so the drill drifted. Ended up ruining the top bit of the thread, but made a longer stud to make use of the undamaged thread at the bottom of the hole...
Andrew
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Old 11-08-12, 11:17 PM   #10
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As Hubert says, if possible weld something on the exposed stud top. But they do have a special rod for arc welders, that erodes the broken stud away. I have no idea how it works though or how effective it is - anyone tried?
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