How does an Automatic Center Punch work?

5 and 6 inch automatic center punch

ALLY Tools and Parts has two types of automatic center punch sets.

6 inch and 5 inch Automatic Center Punch Set and our 3 piece 6 inch Automatic Center Punch Set.

Ever wondered how an Automatic Center Punch works? This article will explain to you the mechanism that create the center punch's ability to impact metal, wood, glass, and ceramic. 

The design for the Automatic Center Punch first started way back in the late 19th century. The most common patents that has been used for mass production of automatic center punches are the Sweet, Adell & Starrett, and Frey patents. The automatic center punch mechanism we will be covering in this article is from the Sweet patent.  

Within the body of the center punch, there are three principal moving parts:

  1. The Punch
  2. The Pin
  3. The Hammer 

The hammer mass is spring-loaded from the back of the punch by a large spring. (The spring's preload compression can usually be adjusted by loosening or tightening the end cap at the back-most portion of the punch, to decrease or increase the force of the punch.) A stopped hole drilled in the front center portion of the hammer faces the pin acts as a receiver for the pin, and as an anvil for the punch action.

6 inch automatic center punch

The pin provides the automation. To reset the center punch back to its original position, the pin rod is cocked slightly, so that its resting position is skewed and the pin contacts the hammer mass on the face of the hammer slightly offset to the hammer's stopped hole. This is commonly done by using a special bent end on the pin spring or using an out-of-flat face on the bottom end of the pin or top of the punch.

How an automatic center punch works

The downward pressure from the punch to the pin bears on the hammer mass and pushes it back against its spring as the punch is pressed, storing energy in the hammer spring. Eventually the stored energy will be released and the hammer spring will expand. This will cause the the punch to dent the material it is placed on. 

You can order our two Automatic Center Punch Sets on

ALLY Tools 3pc 6in Heavy Duty Automatic Center Punch Set on

ALLY Tools and Parts 3 PC SET of 6 Inch Heavy Duty Automatic Center Punch Set


ALLY Tools 2pc 6in and 5in Automatic Center Punch Set on

ALLY Tools 2pc 6in and 5in Automatic Center Punch Set on

5 inch Automatic Center Punch

Older Post Newer Post