"Take The Easy Way Out"

Some of the repair work we receive involves situations where the customer has already attempted to do it himself.  Perhaps he has a bearing race he can't get out of a hole, or off a shaft.  Maybe he's got a part that has a broken bolt or screw.  We become heroes when we are able to fix these problems.  Here are some ways that we use  to do it.

Bearings are usually pressed on a shaft, or into a bore.  When they wear out or get damaged, they need replacement. The average mechanic can usually press or hammer the bearing off, but sometimes they run into problems.  Perhaps the bearing race is in a blind hole and he can't get leverage behind it.  Perhaps it's up against a shoulder on a shaft.

An arc welder can be a valuable tool to remove internal bearing races, even in blind holes.  Simply run a bead of weld around the middle of the race.  This will shrink it, allowing it to be easily removed using a screwdriver or similar tool.  If the bearing is large enough, say two inches or more, it may even fall out when you turn the part upside down.

For races on shafts, an acetylene cutting torch comes in handy. With due care, a race can be cut without burning into the shaft.  Cut thru the bearing length on both sides of the shaft and it falls off. This does require care and experience with a torch, so take it to your machine shop if you don't have the experience, or when the part is too expensive to risk.

Small shafts may warp under the heat of a cutting torch, so find another way to repair them. One possibility is to break the race by hitting it with a hammer, or by squeezing it in a vise or arbor press. Small bearings are often easy to break this way. There is always a possibility of damaging the shaft. You might need to use a chisel or punch to direct the blow. This can be dangerous if not done properly. Always use your head to avoid damaging the part, or yourself.  It might be best to take the part to your machinist.  He has the tools and experience to do the job in a safe, effective way.

Customers who bring us parts with broken bolts or screws have usually tried to remove the broken fasteners themselves. Often, they have broken an "easy out", drill, allen wrench, or screwdriver in the attempt. This always complicates the job of removal.

So called "easy out" tools sometimes work, but their use needs to be limited to easy situations.  If the bolt broke because it was "frozen" in the part, the odds are that an "easy out" is going to break as well. Why would it be stronger than the bolt, because it's harder? Harder also translates into more brittle.  Once it's broken off inside the screw,  it's gonna be expensive and take time to remove.

The process of drilling a hole and driving the "easy out" tool into the bolt can also cause complications.  The drill can slip off center and even damage the threads, especially when you don't center punch the bolt. Such tools encourage a do-it-yourselfer to think he can save money.  He often spends much more money paying his machinist to fix the problem after he has messed it up.

So, how do we remove broken bolts and screws?

We can often remove smaller screws & bolts using a small pointed punch, similar to a nail set punch, positioning it off center toward the threads, and angled to unscrew the bolt as we tap it with a hammer.  We also use this method to remove flat head screws that have the slot, philips, hex, or torx damaged.  Of course, you can also drill a flat head with a drill larger than the screw thread size to remove the head.  Then the bolt is usually easy to remove.

Sometimes we can use needle nosed pliers to grab a portion of the screw and unscrew it.  If the bolt is large enough, say 5/16 of an inch or larger, we may weld a bead on the bolt. We can then file or grind flats on that weld bead and unscrew the bolt. We may even weld a smaller bolt to it with a resistance, arc, or TIG weld.  If the weld holds, we can unscrew the bolt.

If the bolt is hard, or broken too deep, these methods may only result in damage to the threads. We use these methods only when we think they have a chance of success, and only for a short amount of time.  If the situation is difficult, we move on to other methods.  We let our past experience guide us.

If the hole goes through the part, we can sometimes drive the screw out using pliers, a screwdriver, or a drill against the bottom of the screw.  Sometimes a left-handed drill can be used to bring the screw out of the part, another very careful process.  We may also use a "easy out" to remove a bolt, but do so very carefully, making sure we are centered on the bolt. We may even use a milling machine to assure that we are centered.  Sometimes we use penetrating oil with or without heat to help us move a "frozen" bolt.

As a last resort, we use an Electrical Discharge Machining process to remove a broken screw or bolt.  The equipment is expensive and requires the use of a drill press or milling machine.  We "burn" a hole through the bolt that is sized to be nearly the same as a tap drill.  Then we can pick the rest of the screw out of the threaded hole.  We can even remove broken taps using this method. The process can take up to two or more hours, so it is an expensive way to remove a screw or bolt. Depending on the part and the situation, it might be better to drill out the bolt and tap a larger thread size.

All in all, you can probably save time and money by taking the job to your machinist to begin with.  It might cost you a few bucks, but may save more in the long run.  Some of our customers have learned that lesson the hard way.