## How to use the threaDoctor?

**The ThreaDoctor is an advanced, online thread calculator. It uses an advanced algorithm for precise calculations of thraed data. Please read the below manual to use it in the best possible way!**

**Units of Measurement**

**Data Input: **The data input must be in the default units of the relevant thread standard.

**Data Output:** The results are displayed by default in the units of the relevant thread standard (mm or Inches). You can change the display unit. However, you should beware that the formal results are in the default units of the thread standard, and other units of measurement are displayed for convenience only.

**Colors**

- White Background – Input fields.
- Yellow Background – Calculated output fields.

**Supported thread Standards**

**United Inch Screw Threads Per ASME B1.1**

**Metric Threads Per** **ISO 68-1, ISO 261, and ISO 965-2**

**Nominal thread paramters**

These basic thread parameters depend only on the thread family, diameter, and pitch^{[12]}. They remain the same in the different thread classes.

- Pitch
^{[12]}in TPI^{[1]}and as distance - Pitch Diameter
^{[2]} - Minor Diameter
^{[3]} - Major Diameter
^{[4]} - Thread Depth
^{[5]} - Thread Addendum
^{[6]} - Thread Crest
^{[7]}Width - Thread Root
^{[8]}Width - Drill Tap Diameter
- Root Truncation height.
- Root Radius.

**Allowance and Tolerances of the Thread parameters**

**These nominal thread parameters are a general guideline. To machine an actual thread, you need additional parameters: **

- Is the thread Internal or External?
- What is the tolerance class of the thread?
- What is the Length of Engagement
^{[9]}? (Only for unified inch threads)

**The thread calculator takes all the above into account to compute the allowed variations of the below parameters:**

- Thread Allowance
^{[10]}. - Pitch Diameter
^{[2]}. - Major Diameters.
- Minor Diameter
^{[3]}. - Pitch
^{[12]}. - Thread Angle.

**Important Note: **The UN threads standard (ASME B1.1) lists all the data for the length of engagement^{[9]} of five times the pitch diameter^{[2]} (5xP). The ThreaDoctor is more sophisticated and considers the length of engagement^{[9]} in the formulas. The results will equal the tabulated figures in ASME B1.1 when you set the engagement length^{[9]} to 5xP.

**Lead Angles**

The lead angle^{[11]} of the thread depends on its pitch^{[12]}, number of starts, and diameter. Our thread calculator displays the lead angle^{[11]} based on these parameters.

**Over Wire Measurements**

Measuring the pitch diameter^{[2]} becomes challenging when you machine a thread and don’t have the required Go/NoGo gauge. In such cases, the most common method is the “Over Wire^{[13]}” measurement. The ThredDoctor includes a module that calculates the tolerance over the wire for your pitch diameter^{[2]} range and the wire diameter. Our thread calculator also shows you the ideal wire diameter and lets you select the wire from a list of standard market wires.