Two glass tables will be used during mass production of the wire
chambers. An idea is to use one table to glue cital rings and ready cathode
planes into the glass frames and second one for wire stringing. At the first
stages of production of chambers we need to provide as high precision of
wires and cital rings positioning as possible. It leaves us freedom to use
precision methods for assembly and alignment of chamber modules and
spectrometer at whole.
     Special screws fixed on the holes into the glass tables will be used
for positioning of cital rings. Precision position of cital rings could be
provided by coaxially fixing of them relatively the screws. It demands to
have close inner diameters of cital rings and outer diameters of screws.
Another problem arises from this demand: we have to move chamber glass frame
from one table to another and again put it on the precision position defined
by the same screws.
     Cital rings have inner diameters in the range 32.00-32.10 mm. Two sets
of screws with precise positioning place (reference surface) for cital rings
were made for tables. Four screws which will be used for gluing cital rings
and cathodes into the glass frame have precise diameters (reference
surfaces) 31.90+/-0.02 mm. Another set has diameters 31.75+/-0.02 mm.
     50-75 mkm mylar film will be used during gluing cital rings into the
glass frame to provide coaxiality of rings and screws. After gluing cital
rings and cathode plane glass frame will be moved to the second table for
wire stringing.
     Measurements of the distances between centers of the holes on the both
tables and between centers of screws fixed on the tables were made to check
possibility to move chamber frame from one table to second one. Top view of
the glass table and cross sections of the table with screws into the holes
and with no screws are shown at the attached figure. Diameter of the glass
table is 760 mm, thickness is 60 mm. Diameters of four holes are 24.80 mm.
	Measurements were made using next gauges:
- micrometer Combimike, range 0-25 mm, +/-0.01 mm;
- T-shape inside micrometer N900, range 19-31.7 mm;
- vernier MITYTOYO, 24", 60 cm, +/-0.02 mm.
     Results are presented below. The table for gluing cital rings is called
"NEW" and one for wire stringing - "OLD" (this table was used for prototypes
production earlier). Two independent measurements of distances between
centers of the screws for "OLD" table made by two persons are presented in
the table.

Distances between centers of the holes:
                             "OLD" table                     "NEW" table
          #1 - #2         367.70+/-0.03 mm                367.69+/-0.03 mm
          #1 - #4         367.70+/-0.03 mm                367.69+/-0.03 mm
          #2 - #3         367.70+/-0.03 mm                367.69+/-0.03 mm
          #3 - #4         367.70+/-0.03 mm                367.69+/-0.03 mm

          #1 - #3         520.01+/-0.03 mm                520.04+/-0.03 mm
          #2 - #4         520.01+/-0.03 mm                520.04+/-0.03 mm

Hole diameters:            24.79+/-0.01 mm                 24.81+/-0.01 mm


Distances between centers of the screws:
                            "OLD" table                     "NEW" table
     #1 - #2    367.67+/-0.03 mm     367.69+/-0.03 mm     367.74+/-0.03 mm
     #1 - #4    367.67+/-0.03 mm     367.66+/-0.03 mm     367.72+/-0.03 mm
     #2 - #3    367.70+/-0.03 mm     367.69+/-0.03 mm     367.72+/-0.03 mm
     #3 - #4    367.67+/-0.03 mm     367.67+/-0.03 mm     367.72+/-0.03 mm


     #1 - #3    519.94+/-0.03 mm     520.05+/-0.03 mm     520.04+/-0.03 mm
     #2 - #4    519.95+/-0.03 mm     520.10+/-0.03 mm     520.08+/-0.03 mm

	The measurements show differences of distances between centers of
two sets of screws are much less than differences of cital rings inner
diameters and precise diameters (reference surfaces) of the second set of
screws. It should allow us to use both glass tables and move chamber
frames from one table to another leaving required precision of chamber
construction.


Yuri Davydov

Description: glass table (top view and cross-sections) , Filename: dist.eps

Created for the The Center for Subatomic Research E614 Project Projects Page.

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