Extracting broken bolt / screw

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Hi;
Often I need to extract broken bolts / screws and am thinking about picking up some left handed drill bits. Usually I have to extract broken steel bolts and screws from aluminum heads and manifolds. Most often they are broke off clean and need to be drilled. When looking at drill bits to purchase, I see they are made of HSS, Cobalt and Titanium. What drill bit material is the best for staying sharp and long lasting life?
Also, please comment on grabit and other extracting methods. What do you think is the easiest way to remove a broken bolt?
Thanks for any advice Pat
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My favorite method is to center up an oversize hex nut (3/8 nut on a 1/4 bolt etc.) over the broken remains, use a mig welder to weld the nut to the broken stud/bolt. Give it a shot of Kroil and unscrew. For small stuff drill a hole in some sheet metal, weld it to the screw, and weld a hex nut to the sheet metal. Lots of Kroil, maybe run it through a couple of heat/cool cycles, be patient. Works 90% + of the time.
Bill
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BillM wrote:

Last time I tried that I found that the busted bolts I had to remove were unhardened, and of some alloy that my MIG welder wouldn't penetrate it worth a damn! let that be a lesson to you, always use Grade 5!
nate
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Any tool for extraction will work but it's the setup that counts.
For the highest success rate it is beset to follow this procedure, especially when removing a hard bolt from a softer surrounding material like aluminum.
1. If broken bolt is above surface grab it with vise grips, use a engraving tool to buzz it out, or turn it with a sharp punch.
2. If this doesn't work grind the surface perpendicular to the bolt. 3. With a magnifying glass if you need one, punch the exact center of the bolt. Re-punch if you are off a bit.
4. Take a small drill and carefully without breaking the bit, drill a pilot hole.
5. Step up to a larger drill that you feel you will not break and adjust the drill location if necessary to make the hole exactly in the center. Drill all the way through the bolt if possible.
6. Now pick the correct size left hand drill, or drill/EZ out combination.
If the bolt is bellow surface and uneven use steps three through six. Pay great attention to step three, four and five.
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On Sun, 30 Dec 2007 16:18:19 -0500, snipped-for-privacy@mucks.net wrote:

Good post. I've never heard of the engraving tool trick.
By "buzz it out", do you mean the vibration helps the bolt to turn easier? Oren --
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http://www.bubbadeals.com/prograbit.html
This is what I saw on TV. That one seemed IRRC to have either 4 or 5 extractors in the set.
Gunner
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Gunner Asch wrote:

Saw that too! Looked pretty good.
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YUP .. . got a set .. .. works great and comes with a lifetime warranty against breakage .. .. ..
Gunner Asch wrote:

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It takes the place of a punch. Orient the engraver so that it pushes the perimeter, or whatever is available in a counterclockwise direction. This will only work if the bolt is not completely seized but just inaccessible.
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On Sun, 30 Dec 2007 18:15:46 -0500, snipped-for-privacy@mucks.net wrote:

Now ya got me thinking to use the engraver for the pilot starter ..reduce the wobble/walk of a small bit.. an avoid a punch (if possible)
Then use the drill bits. Oren --
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wrote:

I have used one of those automatic punches chucked up to a drill press that is not spinning. Easy down until you get it right and clamped. If I try by hand, it seems to run off. If surface is slanted, you can also place shims under the clamp to flatten out the angle so the hole happens pretty close to center.
Steve
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Oren wrote:

If you have one, I don't see why it wouldn't work. Or at least make a little dimple precisely in the middle so the punch doesn't skate off center when you whack it.
nate
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wrote:

as hard and as much as possible without destroying it often helps a great deal in freeing the bolt from the corrosion which locks it tight. If you can be lucky enough to drill the stub not quite all the way through, you can insert a punch into the hole and stretch the bottom of the stub. This will nearly always free it.
Don Young
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    [ ... ]

    [ ... ]

    This is (I think) the kind of engraving tool which has a carbide point in an adjustable vibrator Something like a "Burgess Vibro-Graver". You place the point on an area away from the center of the broken bolt, but not too close to the threads, and angle it so is is driving both down into the bolt and CCW. This is likely to get the bolt out -- though to be honest, I've never tried it.
    I'll have to remember to try that next time I have that problem. :-)
    Enjoy -- and now "Happy New Year",         DoN.
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wrote:

I have had several bolts break off flush, and could still be turned with just the point of an ice pick, or one of those little dental tools. A "buzzer" would impart a little force on there. Putting penetrant on there and leaving it sit surely wouldn't hurt. Critical points is that the threads are not boogered up, and that you put the point on the broken piece and keep it towards the center away from the threads. A lot of times, the break leaves a slight "shoulder" that the point can be pushed against.
Steve
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SteveB wrote:

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SteveB wrote:

Yup, I've done that many times, usually using a piece of hardened steel shaft (actually often a broken "knockout pin" from a cold heading machine, because that was the type of machinery I was working on) ground to a fine point on a bench grinder and a 3 lb. hammer. A nail might work in a pinch although you'll undoubtedly ruin it - the modified knockout punch was reusable, so I only had to make one every couple months or so. That only works on bolts that have broken due to fatigue or overtightening though, not ones that snapped when loosening due to threads being seized.
nate
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DoN. Nichols wrote:

In that case, what's the point of the vise grips?
This suggestion needs more explanation to make any sense to me -- if the bolt is so bound as to have caused it to twist off in place, seems unlikely this is going to work -- although I've no such engraving tool, either.
I'm the heat cycle kinda' guy, meself... :)
I do like the idea of the tack-weld a new nut on -- now if I only had a MIG or wire-feed unit instead of (or in addition to) the stick... :)
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Sometimes a bolt head will shear off because of sideways forces, and not be in the threads hard. Sometimes there is not enough sticking up to get a vise grip on there. I have had several that once you got it turned a couple of turns with an ice pick, you could get it the rest of the way out with your fingers.
They're all different.
Steve
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Who's to say the bolt broke because of torque?
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