Drill Doctor 750SP - Manual (Page 6)

INSTRUCTIONS
5
STEP 2: Aligning Drill Bit For Sharpening (continued)
E. Look into the opening in front of the paddle. Note the location of the
two spring steel pawls. Rotate the drill bit until the pawls slip in and
grab the flutes at the narrowest point. Continue to push the drill bit
against the drill stop (see Figure 9).
F. With the drill point against the drill stop and the pawls in their correct
position, tighten the chuck by turning the chuck knob CW with the
other hand. Push the paddle
back again to release the drill bit.
Remove the chuck and drill assembly from alignment tube . Snug
the chuck knob CW using both hands to secure the drill bit in the
chuck.
STEP 3: Sharpening The Drill Point
A. Turn the Drill Doctor® switch on.
B. Place the chuck into the sharpening tube
. Align the high part of the
cam with the top cam follower and push it in all the way. This will pre-
vent the drill bit from crashing into the wheel.
C. Lightly pushing INTO the sharpening tube (see Figures 10&11).
Rotate the chuck CW in half rotation increments, similar to the motion
used to turn a doorknob. Rotate the chuck 12 to 20 times on a medium
size drill bit 1/4” to 3/8”. It will take more rotations for larger drill bits
and as few as 2 rotations on small drill bits. The sharpening tube will
move in and out during this process. Let the cams dictate the natur-
al in and out sharpening motion. The sharpening will occur in the “val-
ley” of the cam. Maintain consistent contact with the cams and cam
followers.
NOTE: The sharpening tube is moving in and out due to the secondary or
feed cam on the chuck riding against the top cam follower. The initial
grinding occurs when the “valley” of the feed cam rides against the top
cam follower (see Figure 12). If at the start of the grind, the feed cam
on the chuck is NOT touching the top cam follower, then it is the result
of the drill point being against the wheel and preventing the feed cam
from touching the follower. As you continue to grind and remove mate-
rial, the feed cam will begin touching the cam follower and start to pro-
duce the correct relief angle behind the drill bit’s cutting lips.
Additionally its important to keep the bottom cam follower in contact
with the high lobes on the feed cam. These cams work together in pro-
ducing the radial grind and proper relief on the drill point.
About Relief Angle Settings
If after aligning your bit and sharpening it, the relief needs to be
increased or decreased, then the following procedure is required.
A. Rotate the alignment tube from the point split setting to the standard
setting to increase the relief. The further counterclockwise the tube is
turned the more relief the drill will have.
B. To decrease relief set the timing tube to the masonry location. The fur-
ther clockwise the tube is turned the less relief the drill will have.
C. Reference Figure 13 and #2 in the troubleshooting section on page 10
for more information on negative relief.
Fig. 10
Fig. 11
Fig. 12
Fig. 13
Wrong Correct
Fig. 9
Follower
Valley
Feed Cam
Push INTO tube
Do not push down
Follower
Negative Relief Correct Relief