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?
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
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!
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.
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.
If this doesn't work grind the surface perpendicular to the bolt.
With a magnifying glass if you need one, punch the exact center of the bolt. Re-punch if you are off a bit.
Take a small drill and carefully without breaking the bit, drill a pilot hole.
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.
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.
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.
"I had intended to say in the initial post that welding wasnt an option for me...I want to learn how to weld..."
*If* you have access to an oxy-acetylene torch with a cutting head, but do not know how to weld, here is another handy-andy "hot wrench" trick. It won't work in every situation, it can be quite messy, and gooey gobs of red-hot sparks may fly in every direction. But sometimes it really works well and may be the only way and/or last resort. In general, the larger the diameter of the broken bolt, the better this works -- and not just for broken bolts, but for broken or seized fasteners of all kinds.
Using a cutting torch head, adjust the oxygen and acetylene pressures as you would to cut a piece of flat steel of roughly the same thickness, or less, as the broken bolt's diameter. Heat the exposed area of the broken bolt as rapidly as possible. Speed is of the essence here, or you may end up welding the broken bolt to the surrounding material (which I have done, thank you). The thing to keep in mind is to prevent the broken bolt's surrounding material from approaching welding temperature. Once this surrounding material begins to glow, it is time to remove the torch, pause, and allow everything to cool down. Then, resume.
When the broken bolt end is red-hot, blast away with the oxygen. This will vaporize the molten metal -- look out for red-hot molten metal blowback upon your person. Repeat as needed until all of the broken bolt has been vaporized. If the bolt was in a blind hole, you will have some slag to clean out. If the bolt hole goes through, you can chase out the larger bits of broken bolt by getting them red-hot also, and blasting away with the cutting torch head's oxygen. In either case, *remember to not allow the surrounding material to attain welding temperature*. Finally, run a tap in and out and the bolt hole should be as good as new. Well, almost as good as new...
Lots of helpful ways here to do many types of bolts and screws. I have found that each one is different. And even two of the same types of, say, bolts, the experience will be different.
But I have found a few things that apply straight across the board, and I learned this at HKU.
First: Look at the situation. Don't be in a rush. Sometimes the best way is the simplest. I have a lot of tools, and sometimes, I tend to overengineer. And sometimes the simplest is the fastest. If it don't work, you won't spend a lot of time on it before going to another strategy.
Second: You will probably get one chance. It will screw up or it will come out. You'll fix it or you will ruin it. Make it a good shot.
Third: LET PENETRANTS WORK. I recently had a turnbuckle that was frozen. I twisted the rod off in my hurry to get it off. Then I heated it with a MAPP torch, applied some 3 in 1 oil and turned off the light. Next day, I bought something like "Blaster" and hit it with some. About five minutes, I wiggled the Vise Grips that was clamped to the stump, and it moved freely. I don't think it was the Blaster, but letting the oil do its work and get sucked in. So, if you use penetrants, let them soak long enough to do their work.
Last: Pay attention to your gut when it says, "It feels like if I twist this any farther, it will snap." 99% of the time, my gut was right.
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.
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.
This method takes "a touch" that I don't have... got a lovely Studebaker exhaust manifold with a melted flange to show for trying it :( guess I need to find something consumable to practice on, but drilling really isn't so bad.
I have found that hitting the stub with a hammer, with or without a punch, 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.
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. :-)
What are you afraid of? It isn't neurosurgery. Harbor Freight has entry level MIG's at decent prices, and for the $$ you spend on one you'll save hours and hours of time that you would otherwise waste screwing around with drills, guide bushings 'easy (not) outs', busted taps and all the other hassles. Bill M is dead right on the technique. Personally, I have quite a few decades of auto repair work involving cylinder heads both high performance and stock. The oxyacetylene torch and the MIG rig are your friends, and you will find, as I did, that the time saving and quality of work is worth more than you realize. HTH
Joe
HF welders make good boat anchors. If you're serious about learning to weld, you can find a used Lincoln or Miller for the same price and have a REAL welder.
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.
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