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Fabrication & Inspection of 80-Pitch Internal & External Threads

By Craig Lawson,2014-11-25 10:17
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Fabrication & Inspection of 80-Pitch Internal & External Threads

    D/N Date Effective Title of Document

    01-032 Fabrication & Inspection of 80-Pitch Internal & External Threads 11/9/06

1.0 Scope

    This specification provides requirements for internal and external ?-80 and 6-80 threads. The requirements in

    this specification apply after all machining and post machining operations (deburring, plating, cleaning, etc.).

2.0 Process Sequence for Internal threads in Aluminum and Stainless Steel Parts

    2.1. Tap 80-pitch internal threads

    2.2. Perform post-machining operations:

    2.2.1.1. Aluminum: Unless otherwise specified, all aluminum parts with internal 80-pitch threads shall be

    anodized per NFI SPEC 01-005. Do not rack on or mask 80-pitch internal threads.

    2.2.1.2. Stainless Steel: Unless otherwise specified, all stainless steel parts with internal 80-pitch threads

    shall be passivated per NFI SPEC 01-015. Do not rack on or mask 80-pitch internal threads.

3.0 Process Sequence for internal threads in Fine Pitch Brass or Bronze nuts

    3.1. Single point cut threads

    3.2. Complete secondary machining operations

4.0 Thread Requirements

    4.1. All internal threads shall meet dimensional and tolerance requirements as noted in the table below unless

    otherwise specified in the drawing.

    4.2. Threads shall be free of burrs, digs and debris.

    Internal Threads and Nuts

    Minor Diameter Pitch Diameter Major Diameter Nominal Size Class Min Max Min Max Min

    1/4-80 2B 0.2360 0.2400 0.2419 0.2448 0.2500

     3B 0.2365 0.2387 0.2419 0.2441 0.2500

    6-80 2B 0.1240 0.1290 0.1299 0.1326 0.1380

     3B 0.1245 0.1279 0.1299 0.1319 0.1380

5.0 Maximum Running-Torque Requirements

    5.1. Maximum running torque is defined as the maximum torque required to rotate a specified thread gage lubricated

    with Dow Krytox 205 (NFI P/N 001710), over the entire length of the internal thread.

    5.1.1. ?-80 Running-Torque Thread-Gage Requirements: ?-80 UNS-3B, PD = 0.2419

    5.1.2. 6-80 Running-Torque Thread-Gage Requirements: 0.138-80 UNS-3B, PD = 0.1299

    5.2. The maximum running torque shall not exceed 10 in-oz. The thread gage shall run smoothly with no noticeable

    bumps or binding over the full length of the internal thread.

6.0 Inspection

    6.1. Verification of 80-pitch internal-thread requirements shall be performed on a lot-sample basis. Lot size and

    sampling frequency shall be approved by the NFI Quality Assurance Group.

    6.2. Verification of pitch diameter shall be performed using an internal-thread Go/No Go gage.

    6.2.1. ?-80 Thread-Gage Requirements: ?-80 UNS-3B, PD = 0.2419 Go / 0.2441 No Go

    6.2.2. ?-80 Thread-Gage Requirements: ?-80 UNS-2B, PD = 0.2419 Go / 0.2448 No Go

    6.2.3. 6-80 Thread-Gage Requirements: .138-80 UNS-3B, PD = 0.1299 Go / 0.1319 No Go

    6.2.4. 6-80 Thread-Gage Requirements: .138-80 UNS-2B, PD = 0.1299 Go / 0.1326 No Go

7.0 Process Sequence for External Threads Stainless Steel Parts

    7.1. Machine bar stock (fine turn or grind O.D.) to remove surface defects

     Author: M.Gonsalves

D/N: 01-032 Title: Fabrication & Inspection of 80-Pitch Internal & External Threads Revision: E Page

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    D/N Date Effective Title of Document

    01-032 Fabrication & Inspection of 80-Pitch Internal & External Threads 11/9/06

    7.2. Single point machine threads

    7.3. Complete secondary machining operations

    7.4. Broach hex as specified in drawing and drill to remove broaching material.

    7.5. Deburr and Electro-polish

8.0 Thread Requirements

    8.1. All external threads shall meet dimensional and tolerance requirements as noted in the table below unless

    otherwise specified in the drawing.

    8.2. Threads shall be free of burrs, digs and debris

    External Threads

    Major Diameter Pitch Diameter

    Nominal Size Class Minor Dia. Max (Ref.) Max Min Max Min

    1/4-80 2A 0.2493 0.2461 0.2412 .2390 .2340

     3A .2500 .2435 .2419 .2402 .2347

    6-80 2A .1374 .1342 .1293 .1272 .1221

     3A .138 .1348 .1299 .1284 .1227

9.0 Inspection

    9.1. Verification of 80-pitch internal-thread requirements shall be performed on a lot-sample basis.

    9.2. Lot size and sampling frequency shall be approved by the NFI Quality Assurance Group.

    9.3. Verification of pitch diameter shall be performed using a thread checker or 3-wire method per requirements in

    the above table.

Change History

    Date Revision Reason for Change

    11/9/06 E 1) Changed major dia of ?-80 3A ext thd from .2468

    2) Added new template

     Author: M.Gonsalves

D/N: 01-032 Title: Fabrication & Inspection of 80-Pitch Internal & External Threads Revision: E Page

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