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Safety, Reliability and Value of Striking Tools

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It all started thousands of years ago. Grogg picked up the jawbone of a T-Rex in one hand and a piece of broken tooth in the other hand. Voila! The first chisel is invented. Early on in our history, man realized he could do more work (or damage!) with the use of struck or driven tools.

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Chisels, punches and wedges are all examples of these types of tools. We graduated from using natural materials such as stone, bone and wood to metals. We found out we could really tear things up when we smacked heavy and sharp pieces of steel! From the time we started using steel for tools, the basic design of punches and chisels has remained unchanged for the most part. Each one has a working end and a struck end.

It has only been in the last few years that things started changing. Many of the changes are related to safety during use, and to some degree, with insurance, insurance claims and various regulatory agencies including OSHA. Add to this the dramatic increase in claims related to workers compensation claims. Tool manufacturers took notice.

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Who knew how dangerous it was to continuously smack metal objects with bigger metal objects against much bigger, heavier or harder objects? Well, it turns out that many of us either already knew or will find out if we continue to use punches, chisels and various other hand tools.

The number of injuries related to this category of tools is higher in percentage than almost any other tool category. The injuries can be categorized in three main groups. The first and most prevalent is the striking injury when the user misses the intended target and hits his or her hand, or the hammer glances off the target and then hits the hand. These incidents cause injuries ranging from abrasions and cuts to broken bones.

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The second type of injury caused by these types of tools is due to flying debris or shrapnel. The material can be from the punch or chisel, the hammer or the work material. The materials can cause various injuries with the most severe usually involving the eyes.

The final group of injuries caused by these tools is harder to identify. There can be long-term detrimental effect to people who use striking-type tools repetitively. When a person uses a hammer to strike a hard object, the stress from the contact between the items is transferred into the user’s body. This vibration can cause long-term physical problems.

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OK, so that’s all the bad news I have to share about the possible dangers of using punches and chisels. I also have some good news about the advances in design and safety surrounding punch and chisel type tools. Just as there are three main types of safety issues surrounding these tools, there are three major safety improvements that have occurred to help make these tools safer to use.

Safety Improvements
One of the most important innovations regarding these tools is also one of the simplest in design. Engineers realized that due to the nature of how these tools are used, it was impossible to keep people from hitting the tool in the wrong place or missing completely sometimes.

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The next best solution was to safeguard the user’s hands and fingers from being hit from errant hammer strikes. Inventors borrowed an idea from Roman soldiers and starting installing shields on chisels and punches. The idea is simple, yet ingenious. The inventors decided to install nearly indestructible hand grips on the shank of the tools. These grips not only give the user a good hold on the tool, they also protect the fingers and hand behind a rigid guard.

The second group of innovations for punches and chisels accomplishes several things. They make the tools safer to use, more comfortable for the user and, finally, many of the changes will make the tools last much longer than ever before.

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This last one is interesting. For many years, the general thought was that punches and chisels were sacrificial tools by their very nature. This meant it was assumed they should be destroyed over the course of their effective lifetimes and that was fine. Read on to learn how this idea was discarded in favor of both economics and safety!

Longer Tools for Longer Life
There has been a trend by punch and chisel manufacturers in the last few years to extend the length of their tools. Manufacturers realized that extra-long tools would accomplish several things. The first is user comfort. Longer shanks allow the user to find more comfortable positions to use the tool.

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But more important than comfort is user safety. The longer shanks serve to move the user away from the work area. This helps reduce injuries related to flying debris from the work material. This design change also allows the user to access and work in areas that were previously inaccessible. This simple change is one of the most effective in terms of benefits to the user.

Tools With a Great Figure
The general shape and configuration of punches and chisels has remained unchanged for hundreds of years. There never seemed to be a reason to redesign such a simple device. After all, it’s just basically a metal stick that you hit on one end, right? Well maybe that’s partially true, but it hasn’t stopped suppliers from coming up with some innovative and imaginative changes to the basic shape of these tools.

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So here’s a pop quiz to see if you remember your high school geometry lessons. Do you remember what shape a parabola is? Don’t fret if you didn’t know the answer. Lots of people, me included, couldn’t have told you what the word means. The easiest way to describe parabola is to tell you to think of an umbrella. The shape of an open umbrella is roughly a parabola.  

More importantly: Why the heck am I talking about parabolas? Because that is the shape that some manufacturers have started using for the business end of their punches and chisels (this would be the end we smack with a hammer). This shape helps to make the tool safer and last longer. Sound familiar? The parabolic shape helps to keep the end of the tool from mushrooming or becoming distorted and ragged.

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Not only can the distorted ends cause injury by cutting the user, but over time the tool will start to fragment and throw debris when struck. The parabolic shape of the head directs the striking force to the center of the tool.

Hard To Get Along With
Along with the other design changes, manufacturers have started to rethink their ideas and methods for heat-treating these kinds of tools. For professional technicians, the concept of metal hardness is a familiar one. Like everything in life, it comes down to compromise. Extremely hard metals are desirable for strength and for impact. The negative side of extremely hard metals is that they can be brittle.

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For many years, manufacturers didn’t really care if a chisel or punch lasted for 20 years, it was expected to be replaced or destroyed frequently. And for many years, tools were hardened to one spec for the entire tool. Usually, this meant the tool was heated up to a certain temperature and then rapidly cooled. This cooling process would give the metal its hardness and hopefully durability.

The problem with punches and chisels is that the two different ends are subjected to very different stresses. The struck end is hit by a very hard hammer face. The cutting end, in many cases, is working against various kinds and shapes of materials. The manufacturers realized that one size doesn’t fit all. In this case its one hardness, that doesn’t fit all (or at least both ends).

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What is the solution then? Simple, a different hardness for the working end than you’ll find on the striking end. Drawing back, or more accurately tempering, the ends is a process where the hardness is modified through cooling. The entire tool is hardened to one specification, usually during the forging process. Then the working end of the tool is reheated then cooled to cause a metallurgic change to occur in the tool. This reheating and cooling of the end of the tool actually releases some stress in the metal and makes it a little softer, which is good. If the tool can bend a little when struck it won’t snap off the tip as easily.

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This variable heat-treating of tools is relatively new in mass-produced tools. There have been advances in the last 10 years, which have made this cost effective for suppliers. Originally limited to traditional open-flame heat-treat processes, many suppliers are now incorporating magnetic heat induction into their heat-treat processes. This amazing technology uses magnetic fields to generate intense heat in a confined area.

Getting a Grip on Things
A relatively new development in punches and chisels is designed to address the issue of long-term injuries caused by vibration. What is the best way to stop noise and vibration? Insulation of course! Several U.S. manufacturers are insulating their punch and chisel lines. By applying a grip made out of closed-cell dense foam, they have been able to dramatically reduce the amount of force that is transmitted to the user. This “insulation” also provides a good, firm grip surface, which should also reduce the number of strike injuries caused by slipping hands and tools flying loose.

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Due to safety concerns and users demanding better and longer lasting products, the manufacturers have responded. These tools are going to work better, last longer and cause fewer injuries than the earliest versions did.

Of course, for the utmost in safe use of chisels, punches and other struck tools, the Hand Tool Institute recommends you always wear proper eye protection, and never strike metal to harder metal. If a struck end mushrooms, you should always replace the tool. Never try to re-dress it, as you will alter the hardness of the steel and it may lead to failure.

Some Additional Safety Guidelines 
• Chisels and punches are used for cutting, shaping and removing metal softer than the cutting edge itself. They may be used to cut cast iron, wrought iron, steel, bronze or copper, or to cut rod, wire, nuts, bolts and sheet metal. Do not use on stone or concrete or as a pry bar or wedge. (There are chisels specifically designed for use on stone and concrete.)

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• The diameter of the hammer face should be slightly smaller than the diameter of the chisel surface. Do not use a hammer that has a mushroomed head or with chips on the face.

• Inspect chisels regularly. Discard any tool that is bent or shows dents, cracks, chips, mushrooming or excessive wear.

• Never use a tool with a deformed cutting edge.

• Check with your tool manufacturer for specific safety and warranty information.

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