ken scharf wrote:

That is a VERY weird capacitor. First of all it tunes through 270
degrees of rotation using a unique shape of rotor plate, stator plates
are triangular. Second weird thing is that the shaft bearings are
insulated from the frame, the rotor is grounded at a single point, a
flexible conductor running though the hollow shaft and grounded at the
rear of the rotor. I have a single gang version of that capacitor that
was 'featured' in the one tube regenerative receiver from the A. P.
Morgan 'Boy Electrician' book from the 50's. National did make scales
for their velvet vernier dials that went through 270 degrees of rotation
for use with these capacitors.

Agree with WEIRD. After goofing around with it I had a heck of a time
getting everything realigned. Never did see a way to completely
disassemble it.
Whats your take on the type of insulating material?

-Bill