# Dividing Head Vs Rotary Table

Rotary tables are for moving a workpiece in an arc around a centre for machining purposes. Dividing heads are for setting a workpiece to a specific angular orientation and fixing it there whilst a machining operation is carried out.

## Dividing Head Indexing Plates (40:1, 60:1, 90:1)

This plate can be used either directly, or through a geared dividing mechanism. In direct indexing the workpiece and plate rotate in a 1-to-1 ratio, and holes are used directly. That is, a plate with 12 holes can divide the workpiece into 2, 3, 4, 6, or 12 equal segments. A dividing head incorporates an internal gear ratio (usually 40:1, 60:1, or 90:1) with the same plates. In doing so, the dividing head enables many more combinations than just direct indexing.

For example, imagine a plate with 15 equally-spaced holes and a dividing head with a 40:1 gear reduction. In direct indexing, a workpiece could be divided into 3, 5, or 15 equal segments. Using the dividing head, the same workpiece could be divided into 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 25, 30, 40, 50, 60, 75, 100, 120, 150, 200, 300, or 600 segments. Essentially, the dividing head acts as if it’s a direct indexer with 600 holes; 15 holes in the actual plate * 40:1 gear ratio. Let’s look at how some of these combinations are possible.

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## FAQ

How accurate are rotary tables?

A rotary table is a precision work positioning device used in metalworking. It enables the operator to drill or cut work at exact intervals around a fixed (usually horizontal or vertical) axis.

Can you cut gears with a rotary table?

The rotary table shows a relative drift between the two positions up to 15 arc seconds within 15 minutes.

What are dividing heads used for?

You can easily cut gears on a Sherline mill with the addition of a rotary table (P/N 3700*), a right-angle attachment (P/N 3701), gear cutters, and gear-cutter arbors. You will also need a means of holding your part to the rotary table; you can mount the part in a chuck, or you can use a blank end mill holder fixture.