From: Lucie Linssen
Sent: 06 May 2004 16:12
To: Andrei Levin; j.a.hill@rl.ac.uk; j.greenhalgh@rl.ac.uk; Dave
Cockerill; Ken Bell; Victor Abramov
Subject: Brackets for OPAL frame

Attachments: WeldingBracket.dxf

Dear all,

I attach the drawing of the Bracket that forms the interface between the OPAL frame and the Backplate.
We are now ready to place the order for 52 such brackets (4 times 13).

Given the short time left before the arrival of the first major mechanics elements here at CERN, we would like to have at least 1 OPAL frame ready to receive a backplate arrangement. For this purpose the brackets are indispensable.

Given the very good flatness of the flange of the OPAL frame, we have decided to screw the brackets directly on the flange without intermediate welded mini-flanges. This represents a financial saving.
At least for the first OPAL frame, we propose to use the Backplate itself as a drilling gauge. Therefore, we will mount the brackets on the Backplate first. Then, with the help of the surveyors, we will place the Backplate+brackets in front of the OPAL frame and mark the holes for drilling in the OPAL frame. The actual drilling will be done by the technicians here at CERN.

The brackets have undergone a number of changes with respect to the original drawing:

1:
The lateral dimension (z-direction) has diminished from 105 mm to 85 mm, because the original brackets extended too much in front of the patch panels.

2:
The height of the brackets has changed from 430 mm to 380 mm, because the original brackets extended beyond the machined surface of the OPAL frame flange.

3:
2 out of 6 holes for positioning on the OPAL frame flange have been removed. This is related to the sequence of mounting (brackets on backplate first).

4: The attachment holes on the OPAL frame sit at radii of 1998 mm and 2058 mm. (For your information, the radii of the present ex-OPAL threaded holes in the flange are 1966 and 2021 mm.)


Please send me you comments on the present drawing,

Lucie