Variometer for Crystal Radio

This is a Variometer. It is used to tune a crystal radio.

Included is a very basic circuit schematic. (It can be modified to improve performance.)
The copper part is the wire.(22 AWG magnet wire)
Holes have not been included for the wire.
4x 0.125 in. bolts and nuts AND a 1/8 in. conductive rod will also be required.
Good luck guys...

This was exported in mm....So scale will need to be adjusted accordingly. (X10) or (1000%)