Striking tools, including punches and chisels have a history that dates back hundreds of years. It is actually believed that these tools might be the first tools our prehistoric ancestors used to carve in wood and stone, and create pieces of clothing.
Although very simple in their constructions, these tools are highly versatile, which makes them indispensable in any tool collection. Professional users put punches and chisels to a different use today: removing bushings and pins, and cutting or splitting steel objects.
The words punch and chisel are sometimes used interchangeably; however an in-depth look at the various designs and functionality shows there are many types, shapes, designs and specific functions for these tools.
There are two types of punches available on the market: solid and hollow.
Solid punches are made of metal rods in a one-piece construction designed to be struck by a hammer. They are typically used to drive objects such as pins or to make impressions on a particular surface.
Solid punches can vary in diameter, length and tip depending on the job to be performed. Below is a brief description and characteristics of the most common solid punches.
Taper Punches - designed for loosening and driving pins. Taper punches are also ideal for aligning existing holes in two or more work pieces prior to bolting or riveting.
Roll pin punches - also known as Pilot Punches are used to drive or remove hollow tension pins, such as tapered and rolled or solid pins.
They feature a similar long head like a pin punch with the difference being that they have a slight bump at the tip permitting insertion into a rolled pin.
Centre Punches - used to make an impression on a material before drilling a whole. When struck, a small indentation is made in the surface of the workpiece.
The indentation allows a drill bit to pierce the material more easily, while preventing bit walking and possible marring of the workpiece.
Aligning Punches - as the name suggests these punches are used to align two or more holes in order insert a fastener. Aligning punches are not designed to be struck; do not use them to drive pins, rivets, or bolts (this is what pin punches are design to do). Their tapered body shape allows holes to easily be gathered and aligned as the punch is inserted.
Pin Punches - used to drive or remove pins, after been loosened by a taper punch.
Pin punches feature a long head, the same diameter as the tip and meant for removing tension or solid pins. Care must be taken when selecting a pin punch.
The proper tip size for a specific application is smaller than the encasing hole yet large enough to make solid contact with the piece being driven or removed.
Prick Punches - similar in functionality to center punches, prick punches should only be used on soft materials such as plastics, sheet metal, wood, as well as to scribe marking lines prior to cutting or riveting.
Maintaining your punches and using them for the intended application are the two basic requirements in order to enjoy many years of safe and reliable service.
A common mistake mechanics make is to use a pin punch to break loose a pin instead of a tapered punch, which is specifically designed to take the heavy pounding required to loosen pins.
Using a pin punch to start the initial removal can result in damaging the punch and the pin, while also increasing the risk for personal injury.
Instead, use a taper punch to start then switch to the pin punch to complete the removal. (it is highly recommended that mechanics have a matching tapered punch for every pin punch in their toolbox).
Hollow punches are used to create a hole by puncturing a surface such as leather or sheet metal. A hollow punch is easily identified by its "exit hole" located near the working end. Its purpose is to allow the punched material to be removed and discarded.
The working end can vary in shape and size depending on the hole required and the material being pierced. It is good practice to place a wood or plastic board between the material being pierced and work surface to protect the working end.
Chisels can be also classified into distinct types based on their indented application: wood, masonry, and metalworking.
In this article we will focus on the metalworking chisels. Once again, similar to solid punches, metalworking chisels are one-piece rod shaped tools made of metal designed to be struck by a hammer.They are primarily used to cut or shape metal.
Below is a brief description and characteristics of the most common chisels.
Cold Chisels - are the most popular type of metalworking chisels, also known as flat chisels. Cold chisels have a flat wide tip (working end) with a cutting edge. The width of the tip gives the chisel its size. Common applications are cutting bolts breaking chain, and removing burrs.
Diamond-Point Chisels - as their name suggests, these chisels feature a unique diamond shaped point. These chisels are used to punch holes and make V-shaped grooves in sheet steel.
Cape Chisels - feature a narrower cutting edge than flat chisels. Cape chisels are designed to square rounded corners in grooves or cut new grooves with square edges in steel.
Rivet Buster Chisels - share the same characteristics as flat chisels with the exception that the cutting edge is offset not centered. The offset design allows the chisel to lay flat and easily slide under the rivet to be removed.
Round Nose Chisels - unlike the cape chisels, these chisels have a round edge on one side instead of a straight edge. The round edge allows them to cut grooves with round bottoms.
Metalworking chisels are very useful for cutting steel objects and materials, when used for their intended application.
One thing to keep in mind when using a metalworking chisel: make sure the object(s) being cut or worked is NOT harder than the chisel itself. Otherwise, the chisel’s point will dull or be destroyed.
If that happens, use a hand file (not a grinder) to re-sharpen the chisel.Using a grinder could result in the chisel losing its temper.
Make sure you follow the following safety considerations when your application requires the use of a punch or chisel:
- Always wear safety goggles when working with punches and chisels.
- Ensure the hammer used in conjunction with a punch and chisel has a head diameter of no more than 3/8" larger than head of chisel or punch.
- Always use a proper punch or chisel holder. NEVER USE A PAIR OF LOCKING PLIERS as they will create sharp indentations that can endanger a user's hands when handling later on.
Things to Consider When Buying Your Next Punch or Chisel
The biggest factor that impacts the strength and durability of a punch or chisel is the steel used in its manufacturing.
A punch or chisel made from premium tool steel and optimally tempered will deliver a tool that has a working end that maintains its edge and shape longer and has a striking end that is hard enough to be struck without chipping or cracking. Make sure you do your research before committing to a particular brand or model.
Some other things to keep in mind:
- Consider what is being cut or driven and determine the diameters, sizes and shapes needed to complete the project
- If you are working in or near sparking working environments consider punches and chisels made of brass, copper beryllium or aluminum bronze.
How to Properly Maintain Your Punches and Chisels
Routine maintenance is a very important step in ensuring a long useful life of your punch and chisel.
As striking tools, most punches and chisels are deferentially tempered. That means the striking end is softer than the working end.
As such when any punch or chisel mushrooms on the striking end, it must be dressed to prevent the mushrooming pieces from chipping off and causing harm.
Conversely at the opposite end (working end) maintaining a sharp and clean edge ensures you a have tool that is safe and ready to complete a job properly.