ADJUSTING FOR TOOTH PROFILE:
Dinasaw Sharpeners are capable of
following many tooth profiles. The profile made by the sharpener is a result of (a) Tooth
stroke (b) Cam timing (c) Grinder head Oscillation (amplitude) and (d) Wheel shape. The
first three are adjustments that are made to the machine while the fourth is either a
function of wear or a result of wheel dressing.
Three types of cams can be supplied with the machine.
The “C” type cam is the most common and is used on skip, straight back teeth
blades such as Simonds Red Streak® or Lennox Wood Master®. The “A” type cam is
used for a tooth form having a convex back with lower clearance angles while the
“U” type cam is made from steel and will sharpen straight shaped blades.
(a) The Tooth Stroke of the feed pawl, as mentioned
previously, has an effect on the transition between the tooth face and the gullet (throat)
and is adjusted by moving the bearing along the translator arm with the screw adjustor
turned with the 4mm Hex Key (Fig.19). Moving the bearing forward (away from cam) increases
the stroke of the feed pawl. This effectively gives more time for the grinding wheel to
move down the face of the tooth before it is moved away. The throat of the tooth will have
a tighter radius the longer the stroke becomes. See Fig. 19. A good starting point is to
adjust the stroke to allow the picker to return 50% into the next tooth before beginning
the advance. (say 28mm (1 1/8”) total stroke for a 19mm (3/4”) pitch)
When the tooth stroke is varied, it
changes the tooth position in relation to the grindstone. Lower the grinding head and
adjust the tooth position screw (Fig.19), so that the grinding wheel passes very close to,
but does not actually touch the tooth face. Remember that the blade has to be advanced one
tooth to see the effect of the tooth position screw adjustment.
(b) Your grinder has the facility to allow the tooth
shape to be varied by adjusting the cam timing. The standard timing produces a smooth
progression from the tooth face into a well-rounded gullet. This may be altered by
loosening the clamping socket set screw in the grinder head cam(7) and altering its timing
with the feed cam. See Fig. 20. Advancing the grinder head cam (7) (turning clockwise)
moves the gullet bottom closer to the tooth face while also deepening the tooth. When
altering the cam timing, do so in small increments. Cam timing is critical and a few
degrees will drastically change the shape of the tooth.
Before you attempt to adjust the cam
timing, make note of where the timing is set. This is gauged by the relationship between
the clamp socket cap screw and the indicator pin in the near side if the camshaft. Press
the inch button until the clamp screw (#8) in the amplitude cam (#7) is exactly vertical.
Now look at where the indicator pin on the camshaft is pointing. Most blades require the
indicator pin to be around 120 to 150 degrees with the clamp screw vertical. To retard the
timing, loosen the clamp screw in the amplitude cam (#7) and turn the cam anti-clockwise
with the allen key. Tighten the clamp screw and press the inch button to see if you have
achieved the desired results. Better access is gained to the socket cap screw if the cam
follower is raised clear. Remember to remove the allen key and lower the follower to
it’s working position before using machine. Advancing the cam deepens the gullet
and moves it towards the tooth face. Retarding the cam has the opposite effect. As a
consequence of moving the cam timing, the tooth height (amplitude) may have to be
adjusted.
Grinder Head Oscillation (Amplitude) has the effect on
total tooth depth (height) and is adjusted by sliding the Amplitude Block (74) either up
or down the motor arm (71). Moving the block towards the motor will decrease the arc
through which the grinder head moves. The block is secured to the motor arm by an 8mm
socket set screw. Do not confuse this adjustment with that performed with the knob (76)
which sets the height of the grinder head. Moving the amplitude slide will require the
height adjuster knob (76) to be readjusted. To help reference the position, the motor arm
is marked with transverse lines (See Fig. 21)
The Amplitude screw will need to
be adjusted in if the amplitude block is moved towards the motor. Failure to do this may result in damage to the blade
and/or grinding wheel due to excessive grinding.
Remember the depth adjustment screw (75) will not
directly affect tooth shape, but merely raise or lower the head to ensure the wheel can
reach the tooth, therefore, adjust it so that the wheel is close to the tooth at some
stage of its cycle.
If the wheel misses the gullet bottom, but touches the
tooth back, greater depth is required. Loosen the setscrew and move the amplitude block
(74) away from the pivot point of the amplitude cam arm (71) (i.e. away from the grinding
head).
If the grinding wheel touches the bottom of the gullet
but misses the back of the tooth, less depth is required. In this case, the amplitude
block (74) is moved towards the pivot point of the amplitude cam arm (71) (towards the
grinding head). This will lower the whole head, so you will need to raise it with the
depth adjusting screw (75) to avoid damage to the wheel by dragging it hard over the
tooth.
General Notes:
*The grinding process tends to leave
a burr on the inside edge of the ground surface. This is best removed with a sharp steel
edge such as a knife being drawn around the blade while still supported by the sharpener
frame. Exercise care not to damage or dull the teeth during this process.
* If setting up the machine for a permanent
installation, allow ready access to the underside of the machine for general maintenance
of the machine.
