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Graham Phantom B44 on a TW Acustic Raven AC1

Hi folks,

I�m requesting your help to fit a Graham Phantom B44 (9�) to a TW Acustic Raven AC1. I�ve bought both second hand and the TT comes with a blank brass arm base that needs to be drilled for the Graham.

I�ve got the 5 (1 + 4) holes diameter but not a clue about their positioning in the brass base. Ideally I would need, in order of preference:

- A drawing with the holes position that I could pass to the workshop that will mechanize the base
- A picture of a drilled base without the arm, so I could develop the drawing out of it
- Some positioning info, like distance of holes from base outer limits, distance between holes, etc

The four small holes position is crucial, because it will set the parallelism of the arm.

Any information about this will be gratefully received.

Thanks and regards

Chema
jbuenech

Showing 1 response by frank_sm

frank_sm
111 posts
 
I can help. I installed my Phantom on an armboard I machined for a turntable I built.

Firstly, spindle to pivot = 217.5mm
Effective length = 235mm
Bob Graham gave me those numbers.

The mounting base I have is the Graham mount with 4 thru holes.
The 4 holes are located on a 2.200 inch bolt circle. I drilled and tapped 4 each 6-32 threaded holes and used stainless steel socket head cap screws.
Now I don't know how much rotation you will have with your armboard in order to orient the arm properly but the 4 holes on the Graham mount are basically 20 degrees of perpendicular.
The most important number is the 2.200 inch bolt circle, each hole 90 degrees apart on that bolt circle. Tell your machinist those numbers and you will have a nice fit.
I bored a 1.750 inch hole through for the arm base but you can get by with perhaps 1.500 inch, not positive on that.
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