Altering Tooth Provile
Dinasaw® Bandsaw Sharpener
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.