DRESSING THE STONE-
Select stone
in correct size. Screw the stone tightly against collar
of the sleeve. Adjust the arm of the dressing stand
so the angle dressed on the stone corresponds to
the angle ground on the valve face. Wipe dressing
stand mandrel free of dust and grit, and put one or
two drops of light oil in the stone sleeve bushing.
Place the stone and sleeve over the mandrel and
adjust the diamond to contact the stone by means
of the knurled head on the outer end of the diamond
nib. Lock diamond nib in place with handle while
dressing stones. Use the
unit to drive
the stone and sleeve. Put just enough pressure on the driving unit to over-
come its vibrating action. Too much pressure causes unnecessary friction.
With the stone revolving, take a light cut by moving the diamond slowly
across the stone by means of the feed lever. Turn the knurled head on the
diamond slightly to take additional cut. Repeat until the diamond cuts the
entire face of the stone, producing a true angle and a fresh cutting surface.
Every new stone should be dressed for angle accuracy before being used,
and should be redressed whenever it is remounted on a stone sleeve. To
dress stone accurately for minimum stone run-out, stand must be clamped to
a workbench.
G R I N D I N G THE VALVE SEAT-
After the pilot has been inserted and the stone and
sleeve is in place insert hex-ball spindle into the
stone sleeve socket and grind for a few seconds
(slightly longer for steel inserts). Stellite seats require
several minutes of grinding depending on eccentri-
city and wear. While grinding support driver lightly
to allow its vibrating mechanism to operate freely. The
vibrating principle is important and pressure on the
action, caus-
driver would overcome the
ing the stone to load rapidly.
Narrow with a 15 stone any badly worn seat
made too wide by the grindina (prevents the valve
seat surface from becoming wider than the valve face).
The
valve seat grinding stone gives an accu-
rate, mirror-smooth face on every job. Lapping valves in their seats is
unnecessary if precision equipment is correctly used and valve seat and
valve face test true with prussian blue or a valve seat indicator.
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