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Change Gears for Threading

The series of gears that drive the lead screw are called change gears because you change them to turn different thread pitches.

Changing these gears varies the speed that the lead screw turns in relation to the speed that the spindle turns. This allows you to cut threads with different numbers of threads per inch.

The calculator below determines the correct change gears for any thread pitch. In some cases, the combination of gears given will produce an approximation of the pitch you need. In these cases the error from the desired pitch is shown.

Change Gear Calculator

Desired Thread Pitch	TPI mm	Enter the desired pitch in TPI (Threads Per Inch) or millimeters (mm from crest to crest). Be sure to click the correct units option (TPI or mm).
Lead Screw Pitch	16 TPI 1.5 mm	Mini lathes sold in the US have 16 TPI lead screws (known as "inch" or "imperial"). Mini lathes sold in most other parts of the world have 1.5 mm pitch (metric) lead screws.
Add 21 Tooth Gear		A 21-tooth gear can provide closer approximations of metric gears for some desired pitches.
Additional Gears		List the number of teeth on any non-standard gears you have (if any), separated by commas (,). The normal set of change gears includes the following gears: 20, 20, 35, 40, 40, 45, 50, 55, 57, 60, 65, 80, and 80 teeth.
		Be patient. It takes a few seconds to calculate.

Change Gears for Threading

Change Gear Calculator

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Contact Us / Company Info / Privacy Policy / Terms & Conditions / Payment Options / Shipping Rates & Policies
Copyright © 2007 LittleMachineShop.com Phone: (800) 981-9663 Fax: (626) 797-7934