What Is An Automatic Center Punch?

What Is An Automatic Center Punch?

Last Updated on by Daniel Lawrence

How keen are you on knowing what an automatic center punch is? Because we are revealing what an automatic punch is in this guide. If you are keen enough, you’d read through to find out what automatic punches are, and why you need them.

What Is An Automatic Center Punch?

An automatic center punch is a hand tool used to produce a dimple in a workpiece (for example, a piece of metal). It performs the same function as an ordinary center punch but without the need for a hammer.

When you deal with a drill, it can slip from the actual position because of a high spinning pin. This becomes annoyingly dangerous to ruin your efforts. Then with a chisel, which is another instrument to work as a guide, a drill is capable to make a hole.

This chisel was actually the center punch that comes with a pointy end. It needs hammering for hole creation. Gradually mechanics came up with a better version, the automatic center punch. Everything was different from then and slipping screws or dangerous drilling was not a problem anymore.

When pressed against the workpiece, it stores energy in the spring, eventually releasing it as an impulse that drives the punch, producing the dimple. The impulse provided to the point of the punch is quite repeatable, allowing for uniform impressions to be made.


The patent history of automatic punches indicates two principal goals for the development of the tool: repeatability of impact, and convenience of operation. Other desirable properties include low recoil when triggered, ease of adjustment, and reliability.

Several designs for automatic center punches have been developed since the late 19th century as improvements over punches requiring the use of a striking tool. The earliest types were not fully automatic, using a captive weight lifted by the user or spring and weight drawn by the user to provide the striking impulse.

Several patents have been issued for these designs, and they continue to be referenced in patents into the 21st century. There are also several examples of hammer and punch combinations intended for one-handed use, but being modeled upon a conventional hammer striking a separate punch tool.

The earliest US patents for the modern automatic center punch were filed during 1904 by Hartley and Stryhal for designs using a leaf spring catch to release the hammer, both assigned to Brown and Sharpe. In 1905, Seitz patented a manually triggered punch that has many of the internal structural elements of some later fully automatic models, and Spalding was granted a patent in 1908 on an application filed in 1904 for a different design of leaf spring controlled fully automatic punch that included easy adjustment of a blow as well as interchangeable, threaded on points.

Adell and Baltzer, of L. S Starrett Co., patented a design with concentric shells and pins in cam slots as the triggering mechanism, and Adell and Starrett received a 1907 patent for a design using a sliding block actuated by a tapered bore in the body to hold back the hammer.

Some of the modifications introduced in the Seiler patent of 1923[13] saw substantial manufacture in the United States, and this patent has been referenced by other patents into the 21st century. This design uses a sliding block similar in concept to the Adell and Starrett patent, but with a coil spring to return the sliding block rather than a leaf spring, but a more involved scheme to slide the block to release the hammer.

The Sweet patent of 1942 is the first description of the most manufactured trigger type in the later 20th century, using a tilted intermediate pin to hold back the hammer until the mainspring is compressed. This design is referenced by a large number of other patents and was the basis for the Frey patent of 1965, which was intended to improve the reliability of the device resetting. This design has also seen substantial manufacture.

There are a variety of other mechanisms used, of varying complexity and reliability, some of which have been patented or had patent applied for into the 21st century.

Better quality modern designs tend to follow on Sweet’s patent or Frey’s patent, though some are based on the Adell and Starrett design.

A variety of other mechanisms also exist and have been used, including cam-based, ball bearings trapped in a sliding collar, and bidirectional mechanisms that take pulling attachments.

Actual Working Mechanism

To understand how an automatic center punch works, you need to go through its actual parts. So, majorly it comes with three segments or sections on its body that on whole operates for making punches.

The three major moving parts are punch, intermediate rod or tumbler, and hammer.

Using a huge spring at the punch’s back, a loaded part is called the hammer. There is a secure cap at the very end of this punch. It helps to adjust the force of the punch. Usually, a user needs to adjust by tightening or loosening it up.

There is also a stopped hole in the hammer mass. This part is usually facing tumbler. Whenever there is a punch action, the stopped hole will act as a taker for the rod. It is also known for being an anvil. The automation action provider part in the automatic center punch is known as a tumbler.

There needs to be slight cocking with this tumbler rod. Once cocked, the tumbler is skewed with the existing position. The hammer mass faces its tip and touches gently. It needs to be in a slight offsetting way to the hole.

There should be a bent end in the tumbler spring. This helps to push and bear back the hammer mass against the spring once the punch is open. So, the hammer spring can store energy for punching.

Hole Making

  • When you work on a workpiece for making a hole, the punch needs to be pressed. This will trigger the tumbler.
  • Next, the tumbler moves further back. It reaches the point of the tapered midsection. So that it can touch the guide hole surface inside the punch body.
  • In the process of going backward, the tumbler will receive a push. This has to be aligned with the tool’s center axis.
  • Once the tumbler reaches the very center, it slides to hammer mass’s receiving hole. This initially discharges the hammer.
  • After so, hammer mass gets the power to move forward. It gets required propelling from the back spring to do so.
  • The tumbler’s tip should bottom out inside the hammer’s hole. This is because of the hole not being deep enough to get inside the hammer mass.
  • Eventually, the force travels from hammer to tumbler and goes through punch. Finally, it meets the workpiece, which causes an accurate hole in it.

You Can Use It For:

  • Window and door fitting no more uses nails. They need proper screwing to get attached tightly with hinges. It demands quite a precise drilling and an automatic center punch is the best thing to help you with that.
  • It’s widely used within the rescue industry. Firemen use this amazing tool to break windows. It can preciously handle tempered glass and block tools as well making the rescue operation much easier.
  • You may want to carry an automatic center punch inside your car. If there’s an accident, this little device will take no time to break the window.
  • Last but not least, your garage needs an automatic center punch in many ways. Drilling becomes safe and easier. Most importantly it opens the road to create any size hole in various metal sheets.

Features You Need To Look Out For

An excellent automatic center punch should be able to make dents on various materials such as metallic, wooden, or other working surfaces. In our guide, we will present the essential factors that you should consider before buying one.

Here are the factors you need to pay attention to when buying an automatic center punch.

  • Material

For the Automatic center punch to last for an extended period and also be able to mark any surface, it should be made of hard material. However, as the quality increase, the price rises. If you are on a tight budget, try to find an acceptable equilibrium.

  • Adjustability

Some models have an adjustable knob by which you can adjust the spring tension. It will help you to vary the force that you apply according to your needs.

  • Bit Sharpness

For the bit to point accurately, it should be narrow. However, after an extended period, the punch bit can become dull, and it could move when you press it. You may want to sharpen it or replace it.

  • Replaceable Bit:

As the bit of the punch can become dull, you may need either to sharpen it or finally replace the punch tool completely. Your budget should spend some money upfront and buy the replacement bit rather than purchasing the entire center punch. In the long run, this will save you a significant amount of money.

  • Comfortable Knob:

Some models in the market have this convenient knob. It allows you to create a lot of marks with ease. That said, your hand will not fatigue in case too many tasks need to complete.

For sure, there are a lot of options in the market when it comes to choosing an automatic center punch. However, you can narrow down your choices by considering the above factors and eliminating those that do not match your criteria. Also, one of the best ways to extend the life of your center punch tool is to use a tool organizer. Tool organizers are known to help categorize and organize all your tools in one place.


You also have an idea why this needs to exist in your mechanical toolbox. You can’t imagine how many doors this one little tool can open.

Making tiny holes is actually a big part of many mechanical chores. You don’t want to mess up with some poor drilling techniques.

So, getting an optimal quality automatic center punch will actually save you from a lot of disaster holes.