Tips for regrinding drill bits

◆Regrinding method [Type SX, Type SC, Type SC-F,Type SC-FQ,Type MX, Type MX-F, Type MX-FQ, Type SS]

Before regrinding

Please confirm wear and damage of cutting edge. When there is large edge chipping, please use CBNC or SDC grinding wheel etc to grind off this part.

( 2 )Rear regrinding

●Please use #280-#400 bowl SDC diamond grinding wheel (diameter of grinding wheel: φ100-200)

1) As shown in figure 1, please grind off the back part of the first back rake angle （θ2）,
make no-sparkle grinding after grinding cutting-edge. Please control the difference of
cutting-edge height not exceeding 0.02mm

2) For SX, SC drill bit for steel application, rotate the drill bit byθ4and then fix it, grind the back of the
second back rake angle. At this time, the edge crossed by the first and the second flanks shall be in the
Core bit (the value of θ1~θ4 is listed in table 1)

3) When regrinding Type MX, MX-F, MX-FQ, SC-F, SC-FQ, SS, after grinding the first back rake angle （θ2）,
don't rotate the drill bit and grind the second back rake angleθ3. At this time, the same as 2, the edge crossed by
the first and the second flanks shall be in the Core bit.

Table 1

	Drill point angle	The first back rake angle	The second back rake angle	Rotating angle
SX	-20°	-7°~10°	-24°~-26°	5°
SC	-20°	-10°~-12°		12°
MX	-25°			─
MX-F				─
MX-FQ				─
SC-FQ				─
SS	-20°			─
SC-F	-25°	-2°		─

	Figure 1 Forming of back rake angle
	Type SX. SC for steel application

The first flank

The second flank

Drill point angle

Level up with the basic reference to Point A & B

The first back
rake angle

Type of SC-F, SS for Cast iron, aluminum application

(View in C direction)

The first flank

The second flank

The second
back rake angle

The edge crossed by the first and the second flanks

(View in C direction)

( 1 ) Regrinding of chisel edge

·Please use #280-#400 plane SDC diamond grinding wheel (diameter of grinding wheelφ100-200）
(The grinding wheel for Type MX, MX-F shall be negotiated through another channel)
·The regrinding of chisel edge shall be made according to the tips for regrinding of Type X chisel edge
·when regrinding SC drill bit for steel application, leave a distance of 0.05~0.1mm in the second
back rake angle (figure 2-a.b）
·When regrinding SC-F, SS drill bit for cast iron, aluminum , leave in the second back rake angle
(figure 2-b)
·values of β1~β3in each figure is listed in table 2

Table 2

	β1	β2	β3	R
SX （2-b）	140°~145°	38°~42°	108°~112°	─
SC （2-a）				─
SC-F （2-b）	132°~138°	38°~42°	108°~112°	─
SS （2-b）	132°~138°	38°~42°	108°~112°	─
MX （2-b）	132°~138°	38°~42°	123°~127°	R1~5
MX-F（2-b）
MX-FQ（2-b）
SC-FQ （2-b）

	Figure 2-a Type SC for steel application

	Figure 2-b/type SX/SC-F/SC-FQ/MX/MX-F/MX-FQ/SS

SX、SC-F、SC-FQ、MX、MX-F、
MX-FQ、SS

SX、SC-F、SS

SC-FQ、MX、MX-F、
MX-FQ