Technical FAQ's
Why does the sharpening
tube move? Is it supposed to move?
The sharpening tube is a critical part
of the sharpening mechanism and helps insure that you will not have negative
relief when you sharpen. You do not want to influence the sharpening
tube, either up or down. While sharpening and rotating the chuck
in the sharpening port, apply light pressure straight into the port, along
the axis of the port.
DD750:
The sharpening tube should have a stiff
spring action to it. The bump located on the top of the sharpening
tube is the upper
cam-follower. The sharpening tube fits into the compound,
which is the black plastic around the sharpening port. Located on
the lower portion of the compound is a large lip containing the lower
cam-follower. The chuck has a cam-liplocated
on the base of the chuck body, containing a swing-cam
adjoining it. As the chuck is rotated clockwise in the sharpening
tube, the swing-camrests
on the lower
cam-followerusing the follower as a guide to swing the drill bit
into the sharpening wheel. The upper
cam-followeris moving in and out as it follows the cam-lip,
allowing the drill bit to move toward the sharpening wheel at precisely
the right time to remove material gradually, from the cutting edge to the
trailing edge. This movement and gradual in-feed creates the radial
grind needed for a drill bit.
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I sharpened my
drill bit, but it doesn't seem to cut very well. Why is the trailing edge
of the bit higher than the cutting edge?
You are probably experiencing the most
common problem arising from drill bit sharpening; a condition called negative
relief. This occurs when the material taken off the trailing
edge of the bit surface (also called the heel), is insufficient, and the
trailing edge is at the same level or higher than the cutting edge.
The sharpening wheel creates a flat cutting surface on the point of the
bit, but this must be "trimmed" in order for the cutting surface on the
bit to work correctly.
Negative
relief can be caused by a defective sharpening tube, the type of
drill bit being sharpened (see the next FAQ), a dirty chuck (see 2nd
FAQ following this one), or by incorrect technique.
The Drill Doctor is designed to automatically
take the correct amount of material off the heel of the bit, for a perfectly
sharpened bit every time. Try sharpening again. Loosen the
chuck and re-align the bit. If you haven't already, be sure you watch
the video that came with your Drill Doctor. Also, make sure you are applying equal
pressure throughout the rotation of the chuck, especially on the
low spots on the cam, so that the chuck stays in contact with all cam follower
surfaces as it is rotated in Port #3.
It is also possible that the sharpening
tube on your Drill Doctor is not working properly. The sharpening
tube is the black plastic tube in which you rotate the chuck while sharpening
in Port #3. Locate the bump at the top of the sharpening tube, and
try pressing in on it. This is the upper cam follower and should
have a stiff spring action to it.
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What should I
know about sharpening specialty drill bits?
First, visually check for the alignment, without sharpening the bit.
Align a bit in the chuck for a standard
118° drill bit. Hold the chuck with the drill bit in it.
Notice the two flats on the chuck (see diagram below). Draw an imaginary
line from the middle of the flat up into the drill bit. The line
should end up on the heel of the drill bit. This procedure will hold
true for drill bit diameters of 3/32" through ½ inch.
If the line does not intersect the heel,
then the alignment tube must be adjusted. Should the line fall to
the right of the heel, move the alignment tube #1, slightly below
the standard setting. If the alignment setting is moved too far,
then the chisel point will turn diagonally, from cutting edge to cutting
edge. If the line falls to the left of the heel, move the alignment
tube #1 slightly above the standard setting. Check the alignment
again and adjust accordingly.
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The bit seems to
"back up"into the chuck as I sharpen - the chuck doesn't hold it firmly.
Try this: Insert a drill bit into the chuck
and tighten it as you normally would. Now holding only the chuck,
press the tip of the drill bit against a hard surface, like a piece of
scrap wood on your workbench. Apply about 25 lbs. of pressure.
Does the drill bit slide back into the chuck under pressure?
If so, this is probably due to a build-up
of sharpening dust inside the chuck. Unscrew the chuck body from
the chuck knob. Using compressed air, a small brush or rag, remove
all sharpening dust particles from the chuck knob pusher and jaws (the
pusher is the piece holding the jaws and springs). Now reinstall
the chuck body onto the knob. As you reassemble, make sure that the
chuck jaws are in the jaw grooves, and that the jaws stay straight as the
chuck body is threaded back onto the knob.
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How many times
should I turn the chuck while sharpening?
This depends on the diameter of the bit
you are sharpening.
It is crucial that you turn the chuck in
Port #3 an even number of
times to ensure that the bit is sharpened evenly. If you turn the
chuck an odd number of times, the bit will not be evenly sharpened.
One turn means turning the chuck 180° It takes two turns for the entire
drill bit to contact the sharpening surface once.
Use this chart to determine the number
of turns for various sizes of drill bits:
| |
|
Bit Size
|
Number of Turns
|
| |
|
¾" |
50 or 60 |
| |
|
½"
|
36 or 40 |
| |
|
3/8"
|
16 or 20 |
| |
|
¼" |
8 or 10 |
| |
|
3/32"
|
2 or 4 |
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How
hard should I push the chuck in while sharpening?
Use a light and consistent pressure. Be
sure to apply this light pressure when the chuck is in the lower part of
the cam. Keep all cam follower surfaces in contact.
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What
is the difference between the 118° and the 135° sharpening angle?
Which angle should I use?
The 118° standard (non-split) general-purpose
high-speed drills are used for drilling soft or mild materials such as
cold rolled steel, aluminum, and wood. A 118° drill point provides
good results, but may cause"walking" at the drill point. Commonly,
a pilot hole is drilled before using a standard drill bit.
The 135° split-point, heavy-duty, high-speed
steel drills feature a heavy web construction for extra rigidity.
Use this angle with hard steels, stainless steel, titanium and other hard
materials. The 135°split-point eliminates "walking" and reduces
thrust. It also produces smaller chips that won't clog up the hole.
Ideal for hand and portable drills where bushings can't be used.
There is no need to pre-drill a pilot hole with the use of a 135°split-point
drill bit.
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Why
would I want to use a split-point bit, and how do I split the point?
Splitting the point gives you a drill bit
that is self-centering. You split the point right after you sharpen
the bit.
To split the point, align the drill bit
on the split-point setting. Sharpen as you normally would, but do
not remove the bit from the chuck. Next, align the flats on the chuck
with the flats on the splitting tube, and insert the chuck into Port #4
(the split-port). Pivot the chuck into the sharpening wheel for a "one
count" (one turn). This splits half the point. Now carefully
pull the chuck out of the split-port, just enough to rotate it 180°,
and pivot the chuck into the sharpening wheel again, to split the other
half of the point.
Now remove the chuck and inspect the point.
Depending on the size of the drill bit, it may be necessary to repeat the
splitting steps until the drill point is split to the middle.
NOTE: It's usually better to grind off
not enough, rather than too much. If the drill point is over-split,
leave the bit in the chuck and try re-sharpening the bit in the sharpening
tube (Port #3) to correct the over-split. If this doesn't work, you
should realign the drill bit and resharpen.
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I can't seem to
change the sharpening angle from 118° to 135°. The loop handle
won't budge.
We use a powerful spring in this mechanism
to make sure the angle is accurate. Unfortunately, this also makes
it a little tough to change angles. Try this: insert the chuck, without
a bit in it, into Port #3 (the sharpening port). With one hand on
the chuck for leverage, you should be able to pull out the loop handle
with the other hand and change the setting.
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Why can't I sharpen
a small diameter bit properly?
Small diameter drill bits (1/4 inch or
less) require a little more care in the alignment process. With small
diameter bits, the chuck jaws turn the bit as you tighten the chuck, thus
misaligning the bit. Set the alignment lever to desired setting (standard
or split-point), align the drill bit and tighten the chuck knob.
Before going to port #3, view the chuck through the back (knob end), to
ensure that the chuck jaws are all meeting the drill bit at a 90°angle.
If the jaws are wrapping around the bit, loosen chuck knob slightly, until
jaws are straight.
Also, too many rotations on small diameter
bits will result in a negative rake angle. For example, with a 3/32"
bit, rotate the chuck 2 or 4 times; with a 1/8" bit, rotate the chuck 4
or 6 times; etc.
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Why is the drill
bit not centered in the chuck?
Prior to aligning the bit, the drill bit
should have a "slip-fit" in the chuck. With the drill bit in the
chuck, turn the chuck knob clockwise (CW). This will close the chuck
jaws onto the drill bit. Turn the chuck knob until it stops then loosen
the chuck jaws slightly by turning the chuck knob (CCW). At this
stage, the drill bit should have a "slip-fit" and will slide in or out
and rotate freely within the chuck.
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Why is the point of
my drill bit flat?
First, check the chuck to ensure that the
chuck jaws are in the jaw grooves. Second, during the alignment process,
the pawls may have been gripping "ON" the flutes of the drill bit.
Re-align the drill bit making sure that the pawls are located "IN" the
narrowest section of the flutes.
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Why is the chisel
point of my drill bit turning after I sharpen the bit?
A turned chisel point indicates that the
drill bit has not been sharpened enough (not continue to rotate chuck in
sharpening port) or that the drill bit has too much relief. Relief
is the amount of clearance between the cutting edge and trailing edge of
the drill bit. To correct too much relief on the drill bit, you will
need to make an adjustment in the alignment. Example: If the alignment
was set on the standard drill bit setting, move the alignment tube clockwise
(CW), halfway between the standard and split-point setting. Align
the drill bit as usual and sharpen.
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Can I sharpen a broken
drill bit?
Yes, you can. To prevent the sharpening
wheel from wearing out prematurely, it is recommended that you use a bench
grinder to put the basic shape back on the tip of the bit. Then,
use the Drill Doctor to finish and sharpen the drill bit.
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