[Halld-tracking-hw] Final drawings feedthrus

[Tim Whitlatch]

Hi Curtis,

 Slava has completed what we hope are the final drawings for the 
feedthru, donuts, crimp pins and inserts.

The dimensions and tolerances are as follows;

Straw OD 0.622 (max) (inches)
          ID 0.611 +.002/-.000

Donut ID 0.4375 +.0020/-.0000 inches
          OD  0.611 + .000/-.002
       concentricity of  two diameters of .002 inched (on diameter)

Feedthru  ID 0.250 +.000/-.002
                OD 0.4375 +.000/-.002
       Concentricity .002

Insert  ID 0.039 ±.0004
          OD 0.250 +.000/-.003

Crimp pin OD 0.039±.0004

The ID of the feedthru will be specially made so the crimp pin stays in 
from slight friction.

End plate straight holes have a true position of 0.005 on the diameter 
(±.0025 essentially)

These dimensions leave .000 to .002 radial clearance at each glue joint.

If all the tolerances were to add up in the wrong direction, there is a 
possibility of straw to straw interference on the straight holes by 
about .006 inches. The nominal clearance straw to straw is .009 inches 
(238 microns). I believe the interferences will not be an issue as the 
likelihood of all the tolerances being in the wrong direction are low.

The drawings can be found at;

http://www.jlab.org/~vgr/CDC%20Small%20Parts%20Final%20Dwg-14Aug2009/

The endplates will be ready Monday.

Please review them so we can discuss Monday and get the parts out on the 
street.

Thanks,

       Tim