We have all experienced screw heads breaking off on occasion and its always quite a job to get the old one out and then trying to fix the damage.
I've tried a couple of tpical screw extraction products such as ones from Harbor Freight and HD, but they both sucked and actually broke while trying to use them.
Occasionally I've seen on TV some magical extractors but we all know what adviertizing is like...
For those of you you may have had success with some and would like to recommend a good solution or two I would greatly appreciate hearing of you choice(s).
I figure, if one purchases something that actually works, it worth the investment rather than buy junk only to throw it away and still have the problem to solve.
Mileage always varies with screw extractors. The screw wouldn't come out in the first place so extracting it is always iffy. The extractor creates outward pressure as it attempts to embed in the screw. That makes the problem worse.
Bets case is don't break it. Soak in wd40 or you favorite penatrating oil for several days. If it will turn at all just work it back a forth carefully. Let soak more.
Another option is to heat the surrounding metal. You really need an oxy/act or mapp torch for this though. Propane is too slow. Sometimes combine heat and soaking.
I often just drill with increasing sized bits until I start to expose the threads. Then a tap will chase out the remaining metal. You need to be really accurate. Helps to use a center puch and really small bit to get exactly in the center. to start with.
Screw extraction can be tricky, depending on why the screw broke in the first place. Sears sells a set of extractors that are kind of interesting, they are like these:
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They also sell smaller ones.
What I like about these over traditional easy outs is that you do not need to drill as deep to get a bite with the extractor.
What size screw do you have and what is the material that it is broken off in? If it is a steel screw broken off in aluminum or brass you can simmer it in an alum solution and rust away the screw and leave the aluminum unscathed.
I've also had my share of problems; they seem worse when I pick a size that's too small. As mentioned, center punches and little drill bits help in getting an accurate center. This helps being able to go bigger.
Never buy discount/tv screw extractors. I know the hype is often overwhelmingly alluring, but it's all crap. Screw extraction is tricky, exacting, and fraught with pitfalls. If you want to avoid costly last-ditch methods, pay attention and spend the $$$ up front.
Good attitude!! ...and dead nuts on!
First, buy a quality screw extractor system. I'm talking quality extractors made of high quality steel and requiring drilling a proper hole first. There are two main types. One is a square shape with little flutes at each corner. The other is a reverse spiral. Both work equally well, but require a precise pre-drilled hole. Typically, both have a square headed drive and require something like a T-shaped tap handle to use properly. I realize this sounds costly, but not as costly as failure.
These can be found at machinist tool supply outlets/shops. Again, better to buy the good stuff, even if you have to do so online. You might also check an automotive parts store. Auto mechanics are always doing broken bolt removal and auto parts stores usually carry pretty good quality screw removal tools. Try your local Napa store.
Second, make sure you have good drills and a center punch. Punch a center. Take your time and be as accurate as you can. Drilling an accurate and straight hole is the primary KEY to success. Use quality high speed steel drills (HSS) to make the hole. Use a good cutting fluid to make a clean hole. It can't hurt to soak the hole/screw with all kinds of lubricants and bolt derusting/breaker solutions. Also, make sure you drill the right sized hole for the screw/bolt size and correct extractor size. Fudging is a sure-fire prelude to failure. Finally, tap the extractor in with a small hammer to get a secure grip, attach the handle, and begin the extraction. If you have proceeded carefully, methodically, and accurately, you should meet with success. If not, there's always EDM ....electrical discharge machining (the costly last ditch option).
OH.... one fellow recommmended a reverse or left handed drill. Can't hurt and sometimes it works, specially with smaller screws. If you want to try it, again drill an straight accurate hole. It will either work and back out the screw ...or not! If it doesn't remove the screw, at least you will have a proper hole to proceed with the extractor tool.
I learned my lesson after a couple of attempts. If this is on an important part, I drop it off at a machine shop and pay a pro to do it. Sounds like others may have had better luck.
On the welding group, several people have reported success welding a washer to the end of the screw and then welding a nut to the washer. Probably easier with larger bolts and may require more welding skill than I have. I'll have to try it some day though.
Invest in a good magnifying glass with a light to ensure that the drill is centered. Use a SMALL drill to start with and maneuver it by changing the drill angle until it IS centered. Then line up the drill perpendicular. Use this small drill to make a pilot hole before going to the finished size hole. I have used this method with #55 pilot drills and a very steady hand. If done right the screw will always come out unless it is welded in place.
The best screw extractors I've ever used were of the type shown in the link below. The type is available from several manufacturers with different brand names but they're all virtually identical.
Tnom is rightfully reinforcing the accuracy dictum that you can't be too careful. The smaller hole is what is commonly referred to as a pilot hole and is used to guide a larger drill dilling a larger hole. You haven't given the screw/bolt size you want to remove, so we are shotgunning advice, here. Along those lines, and in the same vein of accurate work, you might consider using a "center drill" to start the initial hole work.
A center drill is commonly used by machinists to begin an accurate hole for whatever type of drilling operation, be it a pilot hole or the final drilling operation. They are short, sharp, and stiff, so not what yer girlfriend ordered! ;) But, they are ACCURATE AND SHARP. You surely can't go wrong by adding one to your tool set and process. In fact, it would probably work better than a pilot drill. Always use high speed drill motors (> 1500 RPM) or you will be adding a broken center drill to the extraction process. They look like this:
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Thanks for the advice and reminder, Tnmm. My geezer mind is a bit rusty. ;)
I'd add that if it's physically possible w/o destroying the DUT, heat on the surrounding part (not the bolt) is the one great leveling factor to break the bond to aid in the removal once got the extractor ready to go...
Yet one more excellent trick to aid in extraction, dph.
OTOH, it matters not how careful you are. The heat will be transferred to the bolt. Fortunately, physics dictate that the hole will enlarge to a slightly greater ID than the bolt/screw's OD, thereby facilitating easing of the overall interference fit of the two. Just make sure you don't cook/bake any added screw/screw-hole lubricants into an interfering paste/sludge. ;)
Yes, there's always that. Might jes shit and fall back in it, too!
Yes, can drill the damn thing out, even oversized, and intall an insert in the now oversized hole. Won't go into induction welding another bolt stub onto the broken bolt or other more esoteric approaches. But, I think most folks responding here have been trying to provide the easiest approach to gettin' the damn thing out with a screw extractor, as per the OPs request.
Drilling to the root of the thread is only the last resort. In order to have success with this method you must be even more accurate with centering the drill. Then you have to cross your fingers that the remaining bolt thread will come out cleanly and leave 100% of the original surrounding steel.
Only if one has machining facilities. A complete drill out requires much more accuracy than a partial hole for an extractor. As a machinist myself, I still recommend an extractor as first choice. If the OP was a machinist with access to a machine shop, I doubt he would asking advice, here.
or if the bolt stub is protruding slightly, you can hold a cheap non- dripless type candle to the bolt and let the wax wick into the threads, heat it again, this time hold an ice cube against the bolt stub or hit it with a can of spray duster. thermal shock can help if nothing else works.
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