Step-by-Step: How Dividing Head Plates Simplify Complex Machining

In modern machining, accuracy and repeatability are non-negotiable. Whether you’re cutting gears in Faisalabad, drilling bolt circles in Lahore, or machining splines in Karachi, one tool plays a major role in simplifying complex operations: the dividing head plate.

A dividing head plate allows machinists to divide a circle into precise parts, making otherwise complex machining jobs both simple and accurate. In this article, we’ll break down step-by-step how dividing head plates work, and why they are a must-have in Pakistani workshops.

What is a Dividing Head Plate?

A dividing head plate (index plate) is a circular plate with a series of accurately drilled holes. When used with a worm and worm gear system, it enables machinists to rotate a workpiece by exact angles.

Main Components

1. Index Plate – The plate with multiple hole circles.
2. Crank Handle – Used to rotate the worm shaft.
3. Sector Arms – Help count the holes accurately.
4. Worm Gear – Provides the precision reduction ratio (often 40:1).

Why Dividing Head Plates are Important

1. They allow precise division of a circle into equal parts.
2. Simplify gear cutting, splines, hexagonal/square shapes, and bolt circles.
3. Save time in repetitive machining tasks.
4. Increase accuracy without requiring CNC machines.

Step-by-Step: How Dividing Head Plates Simplify Machining

Let’s go through the process in a step-by-step guide:

Step 1: Setup the Dividing Head

Mount the dividing head on the milling machine table.

Align it properly with the spindle axis.

Insert the index plate and secure it.

Step 2: Calculate the Division

Identify how many divisions you need.

Formula:

Numberofcrankturns=40NNumber of crank turns = \frac{40}{N}Numberofcrankturns=N40​

Where 40 is the worm gear ratio, and N is the number of divisions required.

Example: To cut a hexagon (6 sides):

406=623 turns\frac{40}{6} = 6\frac{2}{3} \text{ turns}640​=632​ turns

Step 3: Select the Hole Circle

Choose the appropriate circle of holes on the plate.

The number of holes should match the fraction of turns required.

Example: For 6⅔ turns, you’ll use 6 full turns + 2 holes on a 9-hole circle.

Step 4: Set the Sector Arms

Position the sector arms on the index plate to mark the exact number of holes to move.

This prevents counting mistakes during repetitive indexing.

Step 5: Perform Indexing

Rotate the crank handle the required turns.

Lock the spindle after each division.

Machine the workpiece (cut, drill, or mill).

Step 6: Repeat Until Complete

Continue indexing and machining until all divisions are finished.

Example: For a gear with 24 teeth → perform 24 equal divisions.

Applications of Dividing Head Plates in Pakistan

Gear Cutting – Spur, bevel, and helical gears.

Bolt Circle Drilling – For flanges and automotive components.

Machining Polygons – Squares, hexagons, and octagons.

Splines and Keyways – Used in textile machinery and auto parts.

Helical Grooves – With universal dividing heads.

Advantages of Using Dividing Head Plates

✅ High accuracy without CNC machines

✅ Cost-effective solution for Pakistani workshops

✅ Easy to learn for students and beginners

✅ Increases productivity in repetitive operations

✅ Flexible – works for gears, drilling, and shapes

Common Mistakes to Avoid

❌ Miscounting holes on the plate

❌ Using the wrong hole circle

❌ Not locking the spindle before machining

❌ Poor alignment with the milling spindle

FAQs – Dividing Head Plates

Q1: What is the standard worm gear ratio in dividing heads?

👉 Usually 40:1, meaning 40 turns of the crank rotate the spindle once.

Q2: How many plates come with a dividing head?

👉 Typically three plates, each with multiple hole circles.

Q3: Can I cut gears without a dividing head plate?

👉 No, precise gear cutting requires accurate indexing—impossible without an index plate.

Q4: Are dividing head plates expensive in Pakistan?

👉 No, they usually come included with the dividing head. Standalone plates cost around ₨ 10,000 – 20,000.

Q5: Which machinists in Pakistan use dividing heads most?

👉 Gear manufacturers, automotive workshops, and engineering institutes.

Q6: Can dividing head plates be used with CNC machines?

👉 CNC machines often have digital indexing, but plates are still used in manual and semi-CNC setups.

Conclusion

Dividing head plates are one of the most practical tools in machining. By breaking down complex operations like gear cutting or bolt circles into simple, repeatable steps, they save time and ensure precision.

For Pakistani machinists:

Students & beginners – Learn with simple indexing using plates.

Workshops – Use them for gear cutting, flanges, and splines.

Industries – Combine with universal or CNC heads for advanced machining.

In short, dividing head plates simplify complex machining into manageable, step-by-step operations, making them an essential part of every machinist’s toolkit.