It never fails! Just when you think you’ve got the whole disassembly thing under control you either twist off a nut, break or round off a screw, or strip out the threads entirely. This can often be a frustrating time-waster with no quick fix available. More often than not, removing the broken piece and/or repairing the broken threads can take longer than all the disassembly work you’ve done to that point. There are however, a few tips, tricks and tools that might make the job easier.
Probably the best piece of advice is not to panic or go at the problem with a bigger hammer. Patience and forethought will go a long way to easing the angst and frustration and allowing you to get on with the rest of the project.
The first line of offense in removing seized fasteners —before you damage them completely, is the use of penetrating fluids. Keep in mind it’s like buying anything else, ‘You Get What You Pay For’. Not all penetrating fluids are created equal. Some you can use the whole can and get nowhere, with others, a little dab’ll do ya. The more costly product usually means it has a chemical composition more effective and better suited to achieving its task.
You want a penetrating fluid that is high in solids and low in solvents. A higher solid content means greater lubricity and ability to penetrate deeply into the tiny cracks and fissures, forcing its way between the threads, the rust and the mating hole. Penetrants with a high concentration of solvents, such as the ever-popular WD-40™ usually evaporate or dry on the surface before much penetration can occur. It’s definitely a good product for everyday, general use, but time being as important as the penetrant itself, it’s not as effective in this situation as others.
The ideal type of product to use would be one of the newer, thin-film technologies with a low surface tension, such as Corrosion-X™, Fluid Film™ and Moovit™ by Lloyds Laboratories which we carry in our stores.
When applying penetrating fluids, apply the product liberally, perhaps even more than once, and go do something else. Give it time to work its way into the threads. Covering the area with cellophane or shrink wrap inhibits drying and keeps evaporation to a minimum.
When you go to try and remove the fastener, start gently at first, you’re trying to ‘crack’ the last points of contact that’s binding the threads.
You should always use new fasteners, but if you need to reuse old ones, a good soaking in a quality penetrating fluid will keep the threads in better shape for future removal.
The Use Of Heat
Often a last resort, the application of heat to a stubborn, immovable fastener can be the catalyst for success. As heat is rapidly applied, it excites the molecules in the metals causing expansion. This expansion can take place at different temperatures and rates for different metals, One of the most common examples is the heating of cast iron manifolds to remove stubborn steel studs. Being dissimilar in structure, the cast iron heats and expands at a rate greater than the steel fastener, which allows a space to form between the two and facilitates easier removal. The added use of penetrants that can withstand high temperatures enhances the chances for success.
Say you strip the drive socket from a slot, Phillips, Robertson, Torx or Allen head screw. Or perhaps the head of a bolt is rounded off so a wrench or socket slips. Before you toss the tools at the wall, shout a few expletives and move on to more drastic measures, there is one solution you can try, Friction Enhancers.
Friction enhancers work by adding microscopic structures to a solution that ‘fills in’ the damaged areas allowing torque to be applied. There is a product on the market sold under the trade name ‘EZ-Grip™ (www.ezgrip.net) which is sold in three grades: Commercial, for everyday home and factory use, and Marine and Aircraft, for use in more adverse conditions. The composition and methodology are about the same but the Marine and Aircraft grades each carry US Military and NSN specifications.
Essentially, the product contains thousands of tiny, hardened, inorganic aluminum cubes that are bound by algin gum in a solution of water and food-grade glycol anti-freeze. The Marine grade substitutes the water/glycol mixture with a light, non-toxic white mineral oil which allows resistance to being washed away in wet and below waterline environments.
On screws and internal drive fasteners, apply a single drop either into the drive or on to the tip of the driving tool. Insert the screwdriver into the damaged drive socket, apply pressure and wiggle the screwdriver until a good purchase is established. When using a drill or power driver it’s very important that you wiggle the driver bit, with pressure, to ensure a good bite before that burst of torque. EZ-Grip™ is also excellent as a preventative. Use a drop when inserting a new screw to help prevent slipping and damage during installation.
On hex head bolts and other externally driven fasteners, spread two or three drops around the inside of the socket or wrench faces, or on the leading edges of the fasteners head. Again, wiggle the tool while applying pressure until you feel a good bite. Maintain the pressure as you turn it out.
Used on pipes and other miscellaneous fastenings, placing a drop or two on the teeth of vice grips, pipe wrenches, pliers, etc, will multiply the gripping force of that tool.
Head Improvisation & Hand Tools
There are three cases where it may be necessary or an option to try head improvisation. If you round off the sides of a hex head bolt, if you strip out the internal drive of an above surface screw or if you shear off the head altogether.
The first two conditions are usually the fault of tools which do not fit the fastener correctly. This may happen as the result of using metric tools on imperial bolts, using worn or wrong size screwdrivers, or even using tools imprecisely made.
Your first option is to try and get the trusty locking pliers around it. At KMS, we carry Irwin Tools (www.irwintools.com), makers of the Original Vice-Grips™. Irwin makes a wide range of both sizes and types VIce-Grips, some designed expressly for this purpose. Waterpump and slip-joint and groovelock pliers can sometimes work, but they are largely dependent on your manual clamping pressure. Knipex makes ‘Alligator’ pliers which is self-gripping but must also be held tight by your own pressure.
In any case, the trick is to have enough squeeze pressure to keep the tool in place while you try to turn it. Any slippage will only increase the damage. So caution is essential, you don’t want to make matters worse and twist whatever is there off completely.
If you can’t get enough purchase with gripping or locking pliers, the next option is to try and cut the fastener to get an edge to work with. On larger fasteners like hex bolts and nuts, you can try cutting or filing two flat, opposing edges and try the grips again. On screw products that are not countersunk, you might try cutting or filing a slot to accommodate a larger screwdriver. Keep in mind though, if a fastener is going to fail, it will ultimately, fail, with little you can do about it.
Useful Removal Tools
There are a number of useful tools on the market designed for the removal of broken studs, bolts and screws. These are options you can consider as an alternative to drilling out and retapping or affecting some other kind of thread repair.
Specialty Stud Removal Tools
Stud and hex bolt removal tools look like a collar that fits around a protruding stud and is usually driven with a ratchet. The key to it working is pressure being applied through a cam on the inside of the collar which makes contact with and tightens against the stud or bolt head. The more force applied, the tighter the cam squeezes.
As a variation on the above, Irwin makes a pair of tools that are designed to aid in the removal of stripped hex headed fasteners and nuts. One is driven by a ratchet, the other for use in tools which use hex shank bits, like a drill or impact driver. These removers are size specific and can usually fit both Imperial and metric sizes. The inside edges are on an angular twist and are sharp along the leading edge to allow them to dig in as the socket is turned.
After The Head Is Gone
On countersunk screws and fasteners which have been twisted off and don’t have anything left to grip, there are basically two choices: Drill them out and retap, repair or replace the original thread or use a broken bolt removal or extraction tool. It is advisable to file the top of the fastener flat and to centre punch to keep the drilling as on target as possible.
Left Hand Drill Bits
One often overlooked method of removing broken screws and bolts, and perhaps the best first choice, is the left hand twist drill bit. These are the same as regular high speed drill bits except the cutting action is in a counter-clockwise direction —the same way fasteners are removed. Since you will likely have to drill a pilot hole at this point anyway, if you use a left hand drill bit, in many cases the drilling process results in removal because you are turning and biting into the stuck fastener in the same direction as removal, while applying downward pressure. Drilling pilot holes with a regular bit can actually enhance tightening.
If the left hand drilling does not remove the offending fastener, there are several designs of extractors available and a specific size extractor must be matched to the specific size screw or bolt. One style requires that a separate drill bit is used to drill a pilot hole into which the extractor is inserted. Two potential perils exist. The material that most extractor tools are made of as much harder and therefore more brittle than your typical steel bolt or screw, making them quite delicate and susceptible to breakage —making things even worse. The other consideration is that you must first drill the actual pilot hole and it must be true and square so the extractor fits properly and so as not to damage the bolt’s threads. We carry several designs of this type. Some extractors, like the Drill-Out™ and Grab-It™ — which we also carry in-store, come with an integrated drill point for simple, two-in-one-step operation. This type of extractor includes both a drill point and a friction removal tool and are designed to turn in a left-handed direction. Of course some extractors are better at doing their job than others, and some work better in certain applications. Some are also more costly than others but consider having to remove an extractor broken inside a bolt or screw. It ain’t pretty.
Thread Restoration, Repair & Replacement
Watch for a follow up to this article on Repairing & Replacing Damaged Threads, and in the meantime, if you’ve got some other helpful tips or tricks on how to remove thrashed and infuriating fasteners, let us know, we’d be happy to pass it along.