Control System for Multiple Stepper Motors

Threading Calculator

Calculations needed for threading are based on the data in the table below.

Input fields are  colored . After setting these to the desired values, click the blue button at the bottom to perform the calculations.

Thread Data
Desired TPI Threads / inch
Thread Pitch

"

mm
Thread Angle ° 60° is the standard for American National Screw Threads
Flat (at root or crest)

"

mm
Threaded Area
Major Diameter

For external threads, the starting diameter needs to be greater than this.

"

mm

U.S. Army TC9-524, Fundamentals of Machine Tools, Figure 7-74.

Use the Pitch Diameter as the planning basis for cutting.

  • For external threads, be sure to put a flat on the crest.

  • For internal threads, be sure to put a flat on the root.

  • These flats make the threads less vulnerable to damage.

  • Some do this by sanding. This has the added advantage of removing any rough spots.
Pitch Diameter "

mm
Minor Diameter

For internal threads, the starting diameter needs to be less than this.

"

mm
Lid
Relief

"

mm
Threaded Area

"

mm
Base
Relief

"

mm
Threaded Area

"

mm

Ernie Conover wrote a great article, "Turning a Threaded Lid for a Box". The article is about chasing threads by hand, but the diagrams in the article outline some other key topics such as relief areas for both the body of the box and the lid.

Questions or comments? Contact us at
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