The Secret Society of Lathe Trolls

jessefreelance · Joined: 12 Jul 2005 Posts: 13 Location: vancouver bc

how is this done?????????????

Analogisit · Guest

A crystal cutting head is essentially a rectangular Rochelle salt crystal that's clamped at one end. As the ac voltage (the audio signal) is applied, the crystal twists, which is translated into movement of the cutting needle. The Rochelle salt absorbs moisture and crumbles over time, so rebuilding it usually involves replacing the crystal (maybe with modern piezoelectric elements) and replacing the soft rubber that supports the needle chuck. After experimenting with an old Astatic head and piezoelectric strips, I gave up and had Gib at West-Tech rebuild one for me a while ago.