• 3D Projects
  • Böhler WA2 Adapter | Servo Adapter | Coupler

The coupler is inspired by the one used for N scale.
It can be used as active (servo) and passive coupler.
The couple margin is about 10mm.
Rolling stock can be lift up without struggling with hooks.

Video: https://www.youtube.com/watch?v=tYiUqqXrRTE

Sources created with OpenSCAD:

• https://gitlab.com/rocrail/rocrail3d/-/tree/master/G/Coupler

• 1 x stainless steel M3 x 22mm
• 4 x stainless steel self tapping screw M2 x 6mm
• 1 x stainless steel self tapping screw M2 x 8mm

Let cool down the bed to room temperature, and gently loose the spring.
The other parts are not soo very sensitive.

Loosen the support with a tiny screwdriver, and push it out:

Use a 3mm metal drill, and clean up the support with a slow rotation speed: ¹⁾

Drill only one side of the coupler; In the other side the M3 screw will be thread in.

Depending on the 3D print quality it could be needed to rasp very little to make rotation between chassis and coupler very easy.

The chassis and coupler can be connected with a M3 22mm threaded screw:


Tighten the screw loosely so both parts can rotate easy:

Only a small edge must be cut off from the servo pad:

Adjust the servo position with the correct PWM before mounting the lever.
Only the spring can get broken, but is printed new again within a few minutes.

For a passive coupler, without servo, the spring must be 2mm longer as commented in the source:

// Drijfstang V1
translate([0,30,0]) {
  LENGTH=24; // 24 voor servo, 31 voor passief. 
...
  // X- Ronde aansluitingen met gat:
  conoff=0; // 0 voor servo, 4 voor passief

This spring connects to the coupler lever and the far most servo mount point.