How To Use A Dividing Head Like A Pro (step-by-step Guide)

By Author: Abdul alim mihran
Total Articles: 8
Comment this article

In the world of machining, accuracy is everything. Whether you’re cutting gears, milling flutes, or machining hexagonal shapes, precision ensures quality. One tool that makes this possible is the dividing head. Mastering it may seem complicated at first, but once you understand the steps, it becomes an essential skill every machinist should have.

What is a Dividing Head?
Purpose and Applications
A dividing head, also known as an indexing head, is a work-holding device used on milling machines. It allows machinists to divide a workpiece into precise equal divisions, making it ideal for tasks like gear cutting, slotting, and drilling equally spaced holes.
Types of Dividing Heads
Plain Dividing Head – Only allows simple indexing.

Semi-Universal Dividing Head – Enables indexing and angular positioning.

Universal Dividing Head – The most advanced type, capable of differential indexing.

Key Components of a Dividing Head
Indexing Plate
A circular plate with multiple hole circles, used to calculate divisions.
Crank Handle
Attached ...
... to the spindle, it rotates according to calculated turns.
Tailstock
Supports long workpieces and keeps them steady during machining.
Chuck and Fixture
Hold the workpiece securely in place.

Basic Principle of Dividing Head Operation
Indexing Method
The dividing head works on the principle of turning the crank handle to rotate the workpiece by a set fraction of a turn.
Direct Indexing
Some heads have 24 holes on the plate, allowing quick division into 2, 3, 4, 6, 8, 12, and 24 parts.
Simple Indexing
Uses interchangeable plates with hole circles for more divisions.
Differential Indexing
Used for non-standard divisions that simple indexing cannot achieve.

Step-by-Step Guide: How to Use a Dividing Head
Step 1: Mount the Dividing Head on the Milling Machine
Secure the dividing head firmly on the machine table, ensuring stability.
Step 2: Align the Dividing Head with the Milling Spindle
Use a dial indicator to align the spindle axis with the dividing head axis.
Step 3: Fix the Workpiece in the Chuck or Fixture
Clamp the workpiece tightly to avoid movement during cutting.
Step 4: Select the Right Index Plate and Hole Circle
Choose the plate that allows the required number of divisions.
Step 5: Calculate the Divisions Required
The formula for simple indexing is:
Number of crank turns = 40 ÷ Number of divisions
(Here, 40 is the gear ratio of most dividing heads).
Step 6: Perform the Indexing and Lock the Head
Turn the crank handle by the calculated amount and lock the head firmly.
Step 7: Make the Cut and Repeat as Needed
Carry out the milling cut, then repeat the process until all divisions are complete.

Example Calculations for Dividing Head Operations
Dividing a Circle into 6 Equal Parts
Formula: 40 ÷ 6 = 6 2/3 turns.

Use an index plate with 18 holes. Move the crank 6 full turns + 12 holes.

Dividing a Circle into 27 Equal Parts
Formula: 40 ÷ 27 = 1 13/27 turns.

Choose a plate with 27 holes and move 1 turn + 13 holes.

Using Differential Indexing for Non-Standard Divisions
For numbers like 73 or 97, use gears with differential indexing for precise results.

Pro Tips for Using a Dividing Head Efficiently
Double-check calculations before cutting.

Keep the indexing plate clean and lightly oiled to prevent rust.

Use the tailstock for long or heavy workpieces.

Eliminate backlash by always turning the crank in one direction.

Common Mistakes Beginners Make
Choosing the wrong hole circle.

Misalignment between dividing head and milling spindle.

Forgetting to lock the head before cutting.

Safety Precautions While Using a Dividing Head
Always stop the machine before adjusting the head.

Keep hands clear of the rotating cutter.

Wear protective goggles to prevent injury from chips.

Applications of Dividing Head in Real Workshop Settings
Gear Cutting
Essential for making spur, helical, and bevel gears.
Milling Hexagonal and Square Shapes
Used in making bolts, nuts, and machine components.
Cutting Flutes on Drills and Reamers
Provides even spacing for efficient cutting tools.

FAQs: Dividing Head Operation
Q1. What is the main purpose of a dividing head?
It allows accurate division of a workpiece for machining operations like gear cutting and drilling.
Q2. How do you calculate divisions?
Use the formula 40 ÷ number of divisions to determine crank turns.
Q3. Can I cut gears without a dividing head?
It’s possible with CNC machines, but in conventional milling, a dividing head is essential.
Q4. What’s the difference between simple and differential indexing?
Simple indexing handles standard divisions, while differential indexing is for unusual divisions.
Q5. Is a dividing head necessary for all milling operations?
No, it’s mainly used for precision work requiring exact divisions.
Q6. What ratio is used in most dividing heads?
Most have a 40:1 ratio, meaning 40 turns of the crank = one full spindle rotation.

Conclusion: Mastering the Dividing Head Like a True Professional
Learning how to use a dividing head may seem tricky at first, but with practice, it becomes second nature. Whether you’re cutting gears, milling hex shapes, or machining precise patterns, this tool ensures accuracy and consistency. By following the step-by-step method, checking calculations, and avoiding common mistakes, you can truly use the dividing head like a pro.