Specification
Effective length = 239.3mm
Offset = 23deg
P2S = 222mm
Overhang = 17.3mm
effective mass = 12.9g no cartridge (based on CW mass and distance calculated for a 6g cartridge)
Gimbal bearing with setscrew Vee cup and carbide pivots, NO bearings.
The arm has been designed to be as rigid as possible. Bearing housings are based on the Technics SL1200 supersized, both vertical and horizontal bearing housings are 20mm thick. The arm post is machined from 4140 chromoly steel 38mm OD. Arm wand has variable wall thickness and taper, 30mm at the bearing housing to 12.7mm at the headshell. I was going to have an integrated HS but machining in one piece was difficult so it was decided to have a removable HS but bolt it rigidly with a split collet arrangement. The advantage here is that adjusting cart is a matter of setting stylus to HS mounting face to 45mm with the side or front of the cart lined up with the HS and it done.
A lot of attention has been paid to mass distribution and inertia so the arm is neutral in any direction of movement. The variable taper is designed to reduce reflected energy back to the HS. The HS and arm wand are made from the same aluminium.
3rd picture is taken with a USB microscope of one of the M4 setscrew cups. The green dots are the reflection of the microscope LED's. Next pic is one of the carbide pivots. The carbide pivots were donated from a tungsten carbide scribe, The cups had a radius forged into the Vee, burnished and polished. The pivots were radiused and polished. Sensitivity is excellent at 4mg vertical.
Next pic is the horizontal bearing housing shown with the EPA-100. The horizontal bearing housing is larger than the whole EPA-100 housing.
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