Differential Indexing Gear Train Calculation for Milling Machines
Differential indexing is an advanced milling machine technique used when the required number of divisions cannot be achieved using simple indexing alone. A gear train is connected to the dividing head so the spindle moves by the correct amount for non-standard gear divisions.
This calculator helps machinists, workshop engineers, and students find suitable gear train combinations for accurate gear cutting, spline cutting, and other precision dividing operations.
When Is Differential Indexing Required?
It is used when simple indexing cannot produce the required number of divisions. Common examples include gears with prime tooth counts or other non-standard divisions.
Basic Formula
Crank movement = Dividing head ratio ÷ Number of divisions
Example
If a 40:1 dividing head is used for 24 divisions, the crank movement is 40 ÷ 24 = 1 + 16/24 turns.
Related Indexing Pages
FAQ
What is differential indexing?
It is a method used to cut gear divisions that cannot be made with simple indexing alone.
Why use a gear train?
The gear train corrects the spindle movement so the required divisions can be produced accurately.