Old Marklin compatible coupler for Gauge 1 (1:32) railroad models

This is a coupler compatible with old Marklin Gauge 1 (1:32 scale) coupler.
It's used for my Gauge 1 / Spur 1 projects to make them compatible with old Marklin rolling stock I own.

I've printed the coupler hook with 0.1mm layer height to make it as smooth as possible for lower connection pressure. Sanding the layers on the hook tip will help to make it even smoother.

The spring is the cheapest one from local hardware store or e-shop with parameters: outer diameter - 6mm, length - 15mm, wire diameter - 0.5mm. It's twice longer that the slot for the spring in the socket, however it provides good pressure to hold the hook straight.

Coupler cover is mounted by 2 screws M2x8mm (thread length is 8mm), I believe 5-6mm will be also sufficient, I didn't have them during assembly to test.

Coupler socket could be cut/modified for your project, however its top edge matches to the line drawn between centers of buffers - see image please. I've designed it using following parameters: height of this central line above the rail head is 33mm (in fact it's height of buffers' centers above the rail head, that is recommended in NEM 303), height of the front hook's tip above the rail head is 20mm.

Please check the video how does it works:

https://youtu.be/9Oy3eyvF-AI

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