Although not one of the most glamorous tools in the working world, the three-hole punch is one the most useful. It is used in all aspects of life including at school, the office and even in an industrial setting. It is used wherever paper needs to be kept together. They come in all different shapes and sizes, depending on the amount of binding that is required.

This project will describe in detail how the three-hole punch works. This includes a three-dimensional rendering of the punch, a moving parts list, an overall parts list and a close-up rendering of the mechanical workings in action.

For the purposes of this project, a common everyday three-hole punch will be used.

Description

The three-hole punch is a very simple tool composed of 6 unique parts. The bottom cover is used to catch the hole pieces made by the punch to be discarded. This piece is designed to hold itself onto the punch base.

The punch base is the main part of the device and serves as the mount for the punch brackets. Holes in the punch base allow the paper pieces to fall into the bottom cover after they have been punched by the pins.

There are three punch brackets, which are welded onto the punch base and serve as the connectors for the device. The punch handle is attached to the brackets via holes in the handle and hooks on the brackets. The punch springs sit in each bracket as well as the pins that do the punching. A hole in each bracket where the spring sits (aligned with the holes in the punch base) allows the paper pieces to fall into the bottom cover.

The punch springs and pins (one each for each bracket) are the actual working pieces of the punch. The spring is attached to the top of the pin via a groove in the pin. The bottom of the spring rests on the bracket itself. The pin is placed through the spring. The pin has a rounded top to work with the punch handle as it is depressed and a contoured bottom to cut or punch through paper easier.

The punch handle (or top piece) is the final piece of the punch. It is used as a lever to depress the pins, which in turn punches the paper.

The bottom cover is made of a plastic composite while the punch base, brackets and lever are made from sheet metal, which is cut and then formed accordingly. The pins and springs are made from stock steel.

A summary of how the punch works is as follows:

1. Paper is placed in the punch in the slot provided in between the punch base and the punch bracket. The paper sits over the holes in the punch base.
2. The punch lever is depressed, compressing the springs and causing the pins to move through the holes in the brackets and base.
3. As the pins move through the holes, the paper is cut (or punched) where it was positioned above the holes.
4. The bottom cover of the punch catches the circular pieces of paper cut by the pins.
5. As the punch lever is released, the compressed springs holding the pins in place return the pins and lever to their starting positions.
6. The paper is removed from the punch.

Parts List

The basic three-hole punch consists of 12 parts (6 unique), seven of which move during its operation. Its material consists primarily of sheet metal, which is cut and bent to form the device. Except for the welding of the punch brackets, the punch is assemble with no fasteners and uses the parts themselves to hold it together. The point at which the lever connects to the bracket acts as the pivot point allowing the punch to operate in punching holes in paper. This results in a durable and inexpensive product.

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