CON-2
X.C. (Continued)
If additional lighting is required for measuring the
seat, DVCD suggests a goose-neck flashlight
similar to the Type A Lamp Assembly Flashlight
(which is manufactured by Standard Molding
Corporation, Dayton, Ohio).
D.
Lapping Disc Seats
The disc seat may be lapped with a ring lap or a
lapping plate. Lapping should be done in an
eccentric or figure-eight motion in all directions,
applying uniform pressure and rotating the disc
or lap slowly. (See Paragraph X.G. for further
information).
E.
Precautions and Hints for
Lapping Seats
The following precautions and hints will enable
maintenance personnel to do a "professional"
job of lapping sets:
1.
Keep work materials clean.
2.
Always use a fresh lap. If signs of wearing
(out of flatness) are evident, recondition the
lap.
3.
Apply a very thin layer of compound to the
lap. This will prevent rounding off the edges
of the seat.
4.
Keep the lap squarely on the flat surface,
and avoid any tendency to rock the lap which
causes rounding of the seat.
5.
When lapping, keep a firm grip on the part to
prevent the possibility of dropping it and
damaging the seat.
6.
Lap, using eccentric or figure-eight motion in
all directions, at the same time applying
uniform pressure and rotating the lap slowly.
(See Paragraph X.G. for further information.)
7.
Replace the compound frequently after
wiping off the old compound, and apply
more pressure to speed the cutting action of
the compound.
8.
To check the seating surfaces, remove all
compound from both the seat and the lap.
Then, shine the seat with the same lap using
the lapping motion described above. Low
sections on the seating surface will show up
as a shadow in contrast to the shiny portion.
If shadows are present, further lapping is
necessary and only laps known to be flat
should now be used. Only a few minutes will
be required to remove the shadows.
9.
When the lapping is completed, any lines
appearing as cross scratches can be
removed by rotating the lap (which has been
wiped clean of compound) on the seat about
its own axis.
10. The seat should now be thoroughly cleaned
using a lint-free cloth and a cleansing fluid.
F.
Lapping O-Ring Seating Surfaces
The contact surfaces of the nozzle and O-ring
retainer are ground, prior to assembly, to provide
metal to metal seat tightness in the event of O-
ring failure.
Refer to Figure 4 (on page 7 of this manual) and
assemble the retainer to the disc holder (D-J
orifice), or disc (K-T orifice), using the retainer
lock screw(s). Apply 3A compound to the retainer
seating surface. Place the retainer on the nozzle
seat and grind the retainer to the nozzle. Once
uniform contact is established, clean the nozzle
and retainer, and repeat the grinding procedure
with 1000 grit compound.
Remove the retainer screw(s) and retainer, and
thoroughly clean the retainer, retainer screws
and disc holder or disc.
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