Din 76a Pdf

flowchart LR subgraph "Standard Thread Undercut Dimensions" direction LR A[External Thread<br>Shoulder] --> B[Undercut Region] end subgraph Dimensions direction TB D1["`g1 / g2** (Undercut Width): 2.5P / 3.5P (std) / 5P`"] D2["`x (Thread Run-Out Length): 3.5P (normal) / 6.5P (long)`"] D3["`r (Undercut Radius): 0.5P`"] end

Are you designing or internal threads (nuts/blocks) ?

Understanding the DIN 76 Standard for Thread Run-Outs and Undercuts

: DIN 76 is frequently used alongside ISO 4755 , which provides similar recommended dimensions for metric thread undercuts . Where to Access the PDF din 76a pdf

The current standard is – Thread run-outs and thread undercuts for metric ISO threads according to DIN 13 . If you meant DIN 76-2 , that covers thread run-outs and undercuts for fine pitch threads.

On a European or international engineering blueprint, a DIN 76 Form A undercut is rarely drawn out with every detailed dimension. Instead, it is indicated using a standard callout note. A typical callout on a drawing will look like this:

Commercial platforms providing engineering documents to enterprises. Free and Educational Resources If you meant DIN 76-2 , that covers

: Without an undercut, a nut cannot be screwed all the way to a shoulder because the thread-cutting tool cannot maintain a full profile until the very end.

In mechanical engineering and CNC machining, a thread undercut—or thread relief—is a small groove machined at the end of a threaded section of a shaft or bolt.

When you look at a DIN 76 technical data sheet , you will typically see three critical values: : The diameter of the undercut. : The width of the undercut. : The radius of the transition. A typical callout on a drawing will look

For external threads, the standard defines the shape and length of the thread run‑out, i.e., the region where the thread profile gradually fades out. This zone avoids a sharp stress‑raising step at the end of the thread, improving the fatigue life of the fastener. For internal threads in blind holes, the standard defines the minimum length of the thread run‑out at the bottom of the hole, ensuring that the full thread can be produced without crashing the tap.

(Transition Width): The width including the run-out angle (usually 30∘30 raised to the composed with power

Thread run-outs (also known as thread run-outs or run-out lengths) are critical because:

| Thread Pitch P | Radius r (min) | Width of Undercut g (approx) | Diameter of Undercut d₃ (max) | | :--- | :--- | :--- | :--- | | 0.5 | 0.2 | 1.5 | d - 0.8 | | 0.6 | 0.2 | 1.5 | d - 1.0 | | 0.7 | 0.4 | 2.0 | d - 1.1 | | | 0.4 | 2.0 | d - 1.3 | | 1.0 | 0.6 | 2.5 | d - 1.6 | | 1.25 | 0.6 | 3.0 | d - 2.0 | | 1.5 | 0.8 | 3.5 | d - 2.3 | | 1.75 | 1.0 | 4.0 | d - 2.6 | | 2.0 | 1.0 | 5.0 | d - 3.0 | | 2.5 | 1.2 | 6.0 | d - 3.8 | | 3.0 | 1.6 | 7.0 | d - 4.4 | | 3.5 | 2.0 | 8.0 | d - 5.0 | | 4.0 | 2.0 | 9.0 | d - 5.7 | | 4.5 | 2.5 | 10.0 | d - 6.4 | | 5.0 | 2.5 | 11.0 | d - 7.0 |

B --> Dimensions Dimensions --> Note1