TM 9-4910-641-14&P
on underside is up. This positions diamond nib on opposite side of stud
and gives necessary travel to dress side of wheel. Set table stop screw,
start machine and feed diamond up to wheel by backing off table stop
screw. Dress wheel by passing diamond across it using hand wheel and
hold table firmly against stop with table traverse handle.
CHUCKING THE VALVE: First clean stem thoroughly with wire
brush to remove carbon and dirt that may cause inaccurate chucking. In-
sert valve into work head so that one end of double end collet grabs stem
as close to head as possible still remaining on ground surface of stern.
This is important to insure stem and valve face being concentric to make
valve seat perfectly. With valve in position set the stop pin, in the center
of the hand nut, by pushing it against the end of the tightened valve. This
serves as a guide for the rest of the valves in this series and saves time.
GRINDING VALVE FACE: With the workhead secured at proper
grinding degree, wheel properly dressed, and the valve having been thor-
oughly chucked, you are ready to grind the valve face.
Start the machine and proceed with grinding the valve face. Feed
valve up to the wheel slowly, making sure coolant is directed onto valve,
and grind in same manner as when dressing wheel but do not let the valve
pass off the wheel. Set traverse handle to most convenient position. Twist
to left to loosen, move to position, twist to right to tighten. Use light feed,
traversing valve across wheel and back again each time before more feed
is applied. If only part of the valve face touches the grinding wheel check
the stem for straightness. If bent discard valve. If straight be sure it
is clean and clean the collet and inside of work head because any foreign
matter will affect the accuracy of the collet. When face is cleaned up,
allow valve to spark-out, i.e. traverse the valve back and forth slowly
across the wheel without feed until no sparks are visible. Back the valve
off the wheel and stop motor. Remove valve from work head, and you will
now be able to observe a quality finish on the ground valve face. Repeat
operation for successive valves. The grinding wheel furnished with machine
gives excellent results on general valve grinding. However, a special
grinding wheel (OV5FH60W) is available for grinding soft steel valves,
and OV5GH80S wheel is for Stellite valves.
If removal of the valve with motor running is necessary, valve may
be removed from workhead in this manner. Back the valve off the wheel
and move table to extreme right, hit hand screw a glancing blow with
hand in direction of rotation. If this is faster than RPM
of spindle,
collet will open. New valve is positioned in head against stop and nut is
gripped lightly with right hand to lock.
BUTT GRINDING MACHINES NOT EQUIPPED WITH MICRO-
METER BUTT GRINDING ATTACHMENT: Position V-rest on front
table stud and lock in position. Move table to rear lining up V-rest with
side of grinding wheel using valve butt as guide.