• Check wear conditions of and damage to the cutting edge.
• If there is serious damage such as fracture on the cutting edge, grind the edge until the damage is all gone.

• Install the drill by using collet chuck. As shown in figure 1, set the drill phase in order that the corner of center cutting edge and the shoulder of outer peripheral edge become parallel to each other when seen from the top.
• As shown in figure 2, rotate the drill (work head) 20° so that the point angle will be 140°
• As shown in figure 3, set inclination angle of the drill (work head) at 9° -11°. This angle will become first relief angle.

• Finishing first relief face on one side of the cutting edge, index the drill 180° and grind the other side until both sides are at the same position.
  * Depth of cut is 0.02 - 0.03mm/ path.
  * Finally decrease depth of cut to about 0.01mm, and finish both sides at the position.
  * For finishing, repeat oscillation 2 - 3 times as slow as possible. This also serves for the purpose of spark-out.
  * Grind until there is no wear or fracture left on the cutting edge. (Please pay attention to the damage at the margin, too.)
  * Grind until lip height difference (axial runout of front cutting edge) is 0.02mm or less.

After grinding first relief face, grind second relief face.

[Preparation]
* As shown in figure 2 of the previous section, keep rotation angle of the drill (work head) at 20° .

• As shown in figure 4, set inclination angle of the drill (work head) at 23° － 27° .

*If inclination angle of the drill (work head) cannot be increased to 23° －27° , get the wheel inclined 15° as shown in figure 5.

[Grinding]

• Grind second relief face, and the ridgeline of first and second relief face will appear.
• As shown in figure 6, it is ideal that the ridgeline is parallel to the line connecting the corner of center cutting edge and the shoulder of outer peripheral edge. Adjust the drill phase while grinding.
• Grind until ridgelines on both sides become one line. By this, the center point at the top will be formed. As such, please be careful not to grind too much or too little.

After grinding second relief face, grind thinning face. Type of the thinning is X-thinning

[Preparation]

• First, set the work head horizontal so that the center of the drill will be horizontal. Drill rotation angle is 0 ° . Set the direction of table oscillation parallel with the center line of the drill.
• As shown in figure 7, set the drill phase so that the line connecting the shoulder of both sides will be horizontal by using a device such as height gage.
• Then, as shown in figure 8, rotate the drill counter clockwise 65 ° when seen from the top.
• Set the vertical position of the wheel so that the open angle of the thinning from the drill center will be 35 ° , as shown in figure 9.
• As shown in figure 10, set the wheel height so that the center line of the drill will be higher than the bottom of the the wheel edge by “ L ” . (Please refer to the formula in figure 10.)

[Grinding]

• As shown in figure 9, grind the thinning face by sliding the table to the direction shown by the arrowhead, pressing the drill against the wheel. Grind slowly adjusting the top end of cut by using a device such as a stopper.
• Adjust the wheel position while grinding so that the measurements of the thinning (X part, Y part) will be the same as those of figure 10. (Dotted lines show the final positions.

After grinding thinning face, grind honed edges. This is the last procedure for regrinding.

• First, as shown in figure 11, grind the edge at the cross section of the thinning edge and major cutting edge with diamond file until it becomes R-shaped.
• Appropriate R size is approximately (0.1 - 0.15) x øD.
• As shown in figure 12, thoroughly grind honed edges on both sides evenly. First, use a diamond file with grain size #400 for honing, and finish by using a hand lap with grain size #1500.
• As shown in figure 13, honing angle is 25 °.
• Change honing width in accordance with tool diameter. (Please refer to table 1.)

This is the end of regrinding.

Please ascertain that all the following specifications are fulfilled before using WSTAR Drill again.

• Lip height difference (axial runout of front cutting edge) <= 0.02mm
• There is no damage left on the cutting edge.
• Appropriate honing is applied to the edge.
• There is no grinding burr.

Diamond wheels Grain size
For roughing : #200
For finishing : #400 -

R-129936

Diamond wheel Grain size : #400 -

R-146074

Diamond files

Round file : P-56006C
Grain size : #600
Half round file : P-68852
Grain size : #400

Hand hone : 000064
Grain size: #1500