Z-Axis_Brake

Note 7 July 2021: It worked, though I had to stiffen it up after a while. But it is superfluous since I use one 8x4 lead screw in stead of the usual 8x8 one, despite the relatively heavy load of a 326x326x6mm etc.
I could not find a cheap one, so I used a Robotdigg "Tr8*4 400mm Leadscrew Threaded Linear Nema17" - part no. 17HS3001-400N84, which is a combination lead screw + motor.

This thing prevents the bed of a Core_XY 3D-printer going down after power-off.
It is greatly inspired by the Anet A8 Z Axis Brake by Gear_Down_For_What, https://www.thingiverse.com/thing:2238760.

1 motor with 1 lead screw can easily handle my 330x330mm >4kg bed assembly. Except for the going down, which is hardly their fault.
It is a familiar problem but I didn't see any simple solution, until I saw what Gear_Down_For_What had come up with. Great idea. Thanks.

The usual stepper motors with 5mm axes are build to withstand sideways forces, but I use a motor with build-in lead screw and I don't kn