An automatic center punch is a hand-operated tool used to make dimples and holes. These tools store energy in a spring. This spring propels a punch into a surface when the tool reaches the set amount of force. Since they are spring-loaded, these tools maintain a standard pressure over time, making their impacts even regardless of the situation in which they are used. An automatic center punch has a range of uses in metalworking, leatherworking and other crafting areas.
The inside of an automatic center punch is mostly springs, pins and weights. When the pointed end, called the punch, is pushed into a material, it slides up into the body of the tool. This compresses a series of springs and increases the potential energy stored inside the tool. A guide pin inside the body is set at a skewed angle, but as forces increase within the tool, it begins to straighten out. When the pin becomes completely straight, it drops into a hole, which releases the springs and transfers the force of the impact to the punch.
These tools are used in a wide range of crafts. They are common for setting up guide markers for further work, decorating surfaces, or creating starter holes for screws. Modified versions of these tools are used for setting material or creating force for impact setting of adhesives.
There is one main difference between an automatic center punch and a standard center punch. The force used to operate a standard tool comes from the user; often, he will hit the end of the tool with a hammer. The force used on an automatic punch comes from the tool itself. This means that the automatic tool operates the same on the first and last usage, while the standard tool varies based on the strength of the operator.
Neither of the tools is automatically superior to the other. An automatic center punch is reliable, but has very little versatility. If a user needs a heavier or lighter impact, they need a different tool or an adjustment to the spring tension. A standard tool has great versatility, but little reliability. Small changes in angle or strength will show on impact. In addition, as the operator fatigues, it will show through on a standard tool, but not on an automatic.
In order to replicate a small amount of versatility but not lose reliability, a hybrid tool was developed. This tool uses a spring, but it is manually pulled back by the user. The spring connects the punch and a weight, and the weight is connected to a pulling handle. When the weight strikes the punch, it makes the impact mark. These tools require less strength and provide a small amount of versatility, but they are generally smaller and only suitable for light jobs.