I bought a car and someone broke off a head bolt. They tightened it too tight. Then they tried to drill it out and down in the hole about 3/4 inch they broke off the tip of a drill bit. Is there any way to get that out? It's only about 3/8 inch.
If the heads not off it should be by now. Drill bits are quite hard. The only "easy" thing to is to cut a slot in what's left and try to screwdriver it out. Possibly with a Dremel cutting wheel. It might be that the bolt snapped off and the remaining piece isn't bottomed out in the hole. That is it might not be locked up and could unscrew easily.
I've never tried it, but I've heard you can wire weld something on to the top of the broken bit and turn it out. Perhaps a bolt so you can get a wrench on the hex head.
If the drill bit is high or even with the block just take a nut that go just over the bit and weld the nut on the bit. As it all is cold try to turn carefully the nut with a wrench to the left, it may come out.
I've done that a couple of times Rich and it works quite well. 2 problems: 1 you need a welder and 2 you'd better be pretty good with it. Again, if the head's not off and it's broken flush with the head my original suggestion might work. If it is flush with the head pulling the head will solve your problem because you'd have plenty to grab with a vise grip or stud puller.
And if you accidentally weld the nut to the head you'll be really screwed.
To share a 'trick' I recently heard about, but haven't had opportunity to try.... For rusted, twisted off bolts, any way to 'get a grip', then to try lightly heating (propane torch?) and melting in candle wax. May take a couple of tries, but am told the wax will seep into the threads and be a lubricant for an easier removal, if that's possible.
BTDT many times. Use a washer, a nut and a wire welder. Lay the washer over the broken bolt/drill bit, use a 3/8 or 7/16 nut on the washer. Using the wire welder weld the bolt and continue the weld to fill the hole in the nut. The heat will loosen the broken bolt due to differences in thermal expansion. Cast iron does not weld easily. When cool screw out the broken bolt. You man need a wrench! I have taken some out with bare fingers. Should it break the nut off, try it again. You are welding to a pretty small surface and it is difficult to get a good weld sometimes.
You guys aren't reading my question. The head is off. The hole is about 3/4 in deep, almost deep enough to put in a heli coil. But there's still the tip of a drill bit in there, maybe 3/8 in. and I need to get it out.
You might try working it out with a small punch by trying to turn it backwards?? A good machine shop should be able to do anything needed but you will have to take it to them?? Bud.
if you have a torch with small tip heat the top of broken piece hot but not melt temp when it starts to cool load it with pb blaster or penetrating oil to see if it will loosen up
I do the washer and bolt trick, but i use a TIG welder, it puts a deep strong weld and since it heats up the stud at the same time, they come out easily once cooled.
Joe, I would try a slim punch, tap the bit on each flute to the left to loosen it , then a strong magnet. BTDT worked for me. Don
The only way I know of to get a bolt out in the conditions that you stated is to laser it out. You will probably have to take the engine out.
If the bolt is broken below the surface of the head a wire welder is useless.
That's what a stick welder and steady hand are good for.
Sounds to me like you're faced with a two-step removal.... 1.) the tip of a broken off drill bit, and 2.) the stud which has been twisted off. The flutes of the broken drill bit have spaces on each side. Take an appropriate sized steel rod and use a Dremel cutting wheel to slot the rod. Continue cutting the slot until the rod will fit into the spaces behind the drill flutes. Grip the rod and work the broken bit loose. Once out, then go after the broken stud in the manner of your choosing.
If you can get the broken drill bit out i would decide what size pilot hole to drill and use a cut off head bolt for a bushing for your pilot hole.If you get through then step up to head bolt size and to tap you might want to think about metric for your replacement thread and stud?? Clear as mud?? Bud.PS,drill your small pilot hole in the bolt with a lathe!! Bud.
There are special drill bits which will hardened material like taps and easi-outs. To keep the bit on track Kenneth's suggestion has worked for me. Just drill a pilot hole through a short 7/16" bolt and wind that into your bolt hole. You may have to chip out the remains of the drill bit.
There is every chance that hole will be damaged, but the fix is relatively easy and entirely satisfactory. The damaged hole can be drilled out to oversize and a Keysert thread inset fitted. These come with more than one OD, so you can choose the one you need to get the job done.
I once had to Keysert all 15 bolt holes in a 1915 block which had been fitted with 1/2" studs. The holes were already too big for a helicoil.
Hope this helps.
Allan from down under.
I know this question asked for experts and that is not me!! When i put the engine back in my 14 i found one of the threads in the hogs head where the lower ball cap bolt's go almost striped!! Nope,i did not pull the engine again,i got the first size larger meteric tap with matching bolt!! Job Done!! With the not perfect jobs we do High speed steel drils will not shatter and brake like carbide tiped!! Bud in Wheeler,Mi.
EDM (Electrical Discharge Machining) well, maybe not. But how about a body shops stud welder dent puller to attach a stud to the chunk of drill bit and yank it out wit a slide hammer?
I have used my wire welders literally hundreds of times for jobs like this. You don't have to worry much about welding to the cast iron block. Even if you do get a little sloppy and splash some of the weld onto the cast, it will break loose easily. If the object is below the surface, I weld onto it, until I can get a nut welded onto it. Don't give up. Sometimes they come out on the first try, and sometimes on the twentieth try. I keep a few pounds of 3/8-16 nuts in the shop for this purpose. The most job I do this on, are Ford and GM exhaust manifold to head hardware. The bolts/studs are prone to breakage.
Joe, I've dealt with the same thing and the only way I could get all of it out was to get small grinding cones for a dremel tool that will fit into the hole and grind it out. It will take a few to get it done along with some frustration but the drill bit will grind away. Be careful to to bump against the sides of the hole or the exposed threads will get ground away also.
I broke a tap in the manifold bolt hole on an MGB about 4 months ago.
I took the head to a shop and they removed the tap with a lazer, put in an insert and charged me $50.
To get that broken drill bit out of there try using one of those spring loaded center punches, i've succesfully used that technique in the past the punch will often shock the drill bit loose or break it into pieces that can be removed.
I am in agreement with Justin H. I have ground a drill bit out with a Dremel tool using a diamond tipped round bit. It will remove it quite fast, it takes a little skill and patience, and it may take 2 grinding bits (they are quite expensive), about $20 each but they do work.
FWIIW, A long time ago in a galaxy far, far away I worked on plastic manufacturing extrusion and blow molding equipment. A old timer taught me how to blow broken bolts out of blind holes with a oxy acetylene torch. If you know what you are doing and have a good torch with 2 stage regulators you can do this and not damage the threads in the hole. Back then my eyesight was a lot better. I doubt that I could do this today while tilting my head back to see through the bottom of my trifocals. Oh and by the way you better have a good set of leathers to do this unless you do not care if you set yourself on fire.
35 Years ago, a welding company representative came to our railcar repair shop and demonstrated a welding rod that was designed for this precise purpose. He clamped the rod in the rod clamp and stuck the rod down into the hole until it touched the tip of the recessed broken stud and arced the rod to the end of it without the rod adhering to the walls of the threaded hole, then, using vice grips, he was able to clamp onto the rod and unscrew the broken stud out of the hole. We were all flabbergasted and bought a box of the miracle rods, which, in all that time, we may have used once, but having them when nothing else would do, made it all worth while. As far as I know that box of rods is probably still somewhere in the machine shop collecting dust.
You should call a welding supply company and ask to speak to the rep with the longest tenure in the welding supply industry and describe this to him. Chances are, he will know what you are talking about and will be able to steer you in the right direction. Heck, if you take the block, they may even be willing to do it for you. Jim Patrick
I have had good luck with cutting off another drill bit of the same size as the broken one with a pneumatic high speed cutoff wheel to mimic the angle of the broken one.
place the cut off drill in a vice and using the same wheel on edge remove material to create two posts standing proud that will slip down into the spaces between the flutes of the broken drill,(they will be naturally triangular witch is perfect) this will give you almost equal removing power as it has biting power. Unlike bolts- drills, taps and easy outs want to back out, so if it moves at all it will usually finish easily. Hopefully not too much damage has been caused by any previous attempts.