D38999/8D517Z20SN Assembly Fixture
Print Profile(1)

Description
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Support my work with a boost 🚀
A lot of CAD work and tolerance testing went into this functional workshop tool until the connector sat perfectly without play. If this holder makes your work easier and saves time during assembly, please leave me a boost and a like! This helps me cover material costs for future fixtures. Feel free to show me your setups as a "Make"! Happy Pinning! ⚡
🔌 The Third Arm for Cable Assembly
Anyone who has ever pinned and assembled MIL-DTL-38999 circular connectors knows the problem: you actually need three hands. When inserting contacts, laying shielding, or during final assembly, the connector must not rotate.
This specially developed holder is the perfect solution for the D38999 / 8D517Z20SN (Shell Size 17 / Normal Keying). It precisely fixes the connector using the integrated grooves, preventing any rotation.
💡 Main Application & Highlights
- The main application: This holder is primarily designed to securely hold the connector housing throughout the entire assembly process and then to serve as an absolutely rotation-proof counter-bearing for tightening the backshell to the specified torque.
- Precise Anti-Rotation: The internal geometry precisely engages with the connector's coding (Keying N), ensuring nothing slips even under high force.
- Maximum Workplace Flexibility:
- Table Mounting: The holder is designed to be permanently and stably screwed to a tabletop or mounting board with two M6 screws through the two diagonal holes.
- Vise: Alternatively, the solid, rectangular base can also be excellently and securely clamped in any workshop vise.
🖨️ Recommended Print Settings
Since this holder must withstand mechanical stress (pressure in the vise and torsion when tightening the backshell), the model is designed for high stability.
- Material: PETG-CF / PETG
- Walls: 3 walls
- Infill: 35%
- Support: The model can be printed easily without support structures as it is positioned flat on the print bed.
License
You shall not share, sub-license, sell, rent, host, transfer, or distribute in any way the digital or 3D printed versions of this object, nor any other derivative work of this object in its digital or physical format (including - but not limited to - remixes of this object, and hosting on other digital platforms). The objects may not be used without permission in any way whatsoever in which you charge money, or collect fees.








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