MULTIDIAMETER DRILLS

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MULTI-DIAMETER DRILLS
SUBLAND
STEP DRILL
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Multiple Diameter Principle

• In most drilling applications, the resulting
  cavity requires one or more additional
  operations in order to create the finished hole.
  Operations
• such as countersinking, counterboring or reaming
  would normally
• require additional tools, setups and run times.
• Multiple diameter tools are constructed with
  specific dimensions and geometry that in use
  perform two or more operations at once.
• By combining the drill with the tools used for
  the additional operations, a multiple diameter,
  multiple function tool is created that provides a
  variety of useful, timesaving benefits.

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Multiple Diameter Principle

• Why Is One Tool Better Than Two Tools?
• Improve Productivity
• Increase Accuracy
• Reduced Setup Time
• Reduced Run Time
• Reduced Tool Inventory
• Minimize Spindle Requirements
• Eliminate Tool Change
• Minimize Part Handling

TIME SAVING SAVING
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Typical Cavities For Multiple Diameter Tools
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Most Common Cavities For Multiple Diameter Tools
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Subland vs. Step
There are two basic construction styles within
the category of multiple diameter tools
Subland Construction and Step Construction
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SUBLAND CONSTRUCTION
Subland Tools An independent set of lands
provided down the entire flute length for each
diameter present in the form.
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What Is A Subland Tool?
A rotating tool for cutting two or more diameters
in a single pass. It may be a drill, a reamer, a
counterbore, an end mill, or a spotfacer or it
may be a combination of these cutting tools on a
single tool body so that you can drill and ream,
drill and counterbore, or drill and spotface in
one pass.
With a Subland tool, you can cut stepped holes
like
This
This
Or Even This
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What Is A Subland Tool?
Definition
A Subland is a two or more diameter tool on a
single body, with each diameter retaining its
own characteristics.
SUBLAND DRILL
Contains
1.) One flute for each diameter extending back
to the shank. 2.) Individual geometry and
chip carrying capability, resulting in a
a clean, square face, due to very good chip
evacuation.
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Subland 2-2
Description A Subland Drill (2-2) is basically
two, 2-flute drills of different diameters
combined into one tool, but retaining the
individual characteristics and proper geometry of
each. Independent flutes and margins of a Subland
drill guarantees that size of the small diameter
and concentricity between diameters are ensured
throughout the life of the tool and are not
affected by resharpening the point or step angles.
Applications The Subland Drill (2-2) eliminates
operations by performing two operations, such
as, drill to drill, drill to chamfer, etc. in one
production step. Its built-in concentricity
assures increased accuracy.
Limitations The Subland Drill (2-2) is not
practical with a small diameter less than 45 of
the large diameter. Depth of the hole should not
exceed three times the small diameter. Greater
depth can be achieved by withdrawing drill to
clear chips.
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Subland Drill (2-2) Nomenclature
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STEP CONSTRUCTION
Step Tools Have a small diameter ground on the
leading portion of the tool, and all diameters
share the same set of flutes and lands.
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Step Drill
Description The Step Drill is a conventional
2-flute drill that has had a second diameter
created by grinding down a portion of the larger
diameter. Though concentricity during
resharpening is more difficult to maintain than
with Subland construction, greater step lengths
and diameter differentials are possible with this
tool style. More than two diameters are possible
on step drills for applications similar to the
Subland 2-2-2.
Limitations The Step Drill is not practical with
a small diameter less than 35 of the large
diameter. If the percentage of the diameter
differential is greater than 45, examine Subland
construction.
Applications The 2-flute Step Drill eliminates
operations by performing two operations in one
production step such as drill to drill, drill to
chamfer, etc., and can be constructed with
greater step length and diameter differential
than with Subland tooling. Subland construction
is recommended when possible for better
concentricity. The Subland Drills small diameter
is not destroyed during resharpening as happens
after repeated resharpening of Step Drills.
Double or triple margins in step tool
construction facilitates more accurate holding in
a collet when recreating the small diameter.
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Step Drill Nomenclature
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Tool Construction Styles
SUBLAND DRILLS
STEP DRILLS
Single Margin
Double Margin
Full Cylindrical
Single Margin
Double Margin
Full Cylindrical
SUBLAND CORE DRILLS
STEP CORE DRILLS
(3-3)
(4-4)
3 Flute
4 Flute
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Subland Construction Advantages
Concentricity
Built-in tool concentricity guaranteed with
subland construction throughout life of tool.
This assures round, accurate holes even after
repeated sharpenings.
SUBLAND
STEP
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Subland Construction Advantages
Life
Total usable life can be utilized to the most
economical degree. Valuable length is not
consumed in establishing new diameters.
SUBLAND
STEP
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Subland Construction Advantages
Geometry
Since each diameter of a subland tool has its own
set of flutes the flute form, rake, web, etc.
for each diameter can be independent of the
others. This results in maximum cutting
efficiency.
SUBLAND
STEP
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Subland Construction Advantages
Sharpening
Reconditioning of Subland tools requires much
less time. Only the cutting edges need to be
sharpened and there is no undercutting at the
step junction, nor does the small diameter ever
need to be reestablished.
SUBLAND
The Only Reconditioning Ever Needed is
Here
Here
STEP
Here
Here
Reconditioning Required
and Here
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Subland Construction Advantages
Edges
Diameter and cutting edge junction points are
always overlapping with subland construction
resulting in sharp, burr-free contours.
SUBLAND
STEP
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Subland Construction Advantages
Size
Tool diameters never have to be recreated on
Subland tools. Size is permanently established
during initial manufacturing. The highest degree
of part consistency is therefore maintained.
SUBLAND
STEP
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Technical/Engineering Information
Step Angle and Length Measurement Standard For
Subland and Step Drills
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Technical/Engineering Information
Subland Number Identification What do The
Numbers Mean?
Each Number Cutting Edges for the Specific
Diameter Two Numbers Two Diameter Tool (2 -2 )
(2 - 4) (2 - 6) (3 - 3) (4 -
4) First Number Cutting Edges on Subland or
Minor Diameter Second Number Cutting Edges on
Large or Major Diameter Three Numbers Three
Diameter Tool (2 - 2 - 2) (2 - 4 - 2) First
Number Cutting Edges on Minor Subland
Diameter Second Number Cutting Edges on
Intermediate Subland Diameter Third Number
Cutting Edges on Major Diameter
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SUBLAND VS STEP WHICH ONE SHOULD YOU USE?
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Subland vs Step Drills
Why should a subland be used when its more
expensive than a step drill ?
Investigate the Hole story Look beyond the cost
to the Tool
1.) Determine depth to diameter ratio. 2.)
Determine regrind capabilities. 3.) Determine
cost per hole.
THE EXAMINER IS YOU!
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Subland vs Step Drills Investigation Procedure
Initial Cost
Step Tool Lower Initial Cost
Subland Tool Higher Initial Cost
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Subland vs Step Drills Investigation Procedure
How A Step Tool Is Manufactured From An
Existing Single Diameter Tool.

• . Take a standard drill from stock.
• . Put in a collet, or establish centers on
  shank and point.
• . Grind smaller diameter on flute end to
  length.
• . May or may not be concentric.
• . Due to two point contact in collet, or
  centers not
• established true to axis.

This may not be a precision ground tool!!!
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Subland vs Step Drills Investigation Procedure
How A Step Tool Is Manufactured From A Existing
Single Dia. Tool
Standard Drill
Collet
Grinding Wheel
Two Point Contact
Grinding Pressure
A Step Drill Is Created
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Subland vs Step Drills Investigation Procedure
Here Is Why You Cannot Indicate A Step Tool
Accurately . . . Regardless of which position you
set the tool, you only have one pair of lands to
hold and indicate. You cannot check in the other
direction. Therefore, if you cannot hold it or
indicate it accurately, you cannot grind it
accurately. The net result is eccentricity
between diameters.
You Cannot Indicate True In This Direction
You can indicate true in this direction
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Subland vs Step Drills Investigation Procedure
How A Subland Tool Is Manufactured
1. Operations performed between centers. 2.
Concentricity guaranteed. 3. Minor diameter
never has to be re-established.
Blank Cut-off and Centers established
Heat Treated Blank Ground Between Centers
Grind Main Flute
Grind Subland Flute
A Subland Is Created
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Subland vs Step Drills Investigation Procedure
STEP DRILL
Two-diameter tool, with both diameters on the
same set of flutes
Single Flute
Subland Flute
SUBLAND DRILL
Two-diameter tool, with individual flutes for
each diameter
Main Flute
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Subland vs Step Drills Investigation Procedure
Maintenance Step Tools
In step tool construction, because you have both
diameters on the same set of flutes and lands,
you will have to create an undercut at the
intersection of both diameters.
It gets weak due to undercutting at
the intersection. This may cause the minor
diameter to break when subjected to minor
strain.
After many grinds, if it doesnt break, there is
no small diameter left.
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Subland vs Step Drills Investigation Procedure
Maintenance Subland Tools
Because you have individual flutes for each
diameter. All you have to do is end grind each
diameter maintaining the same step length
dimension. You will never have to grind the tool
diameter
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Subland vs Step Drills Investigation Procedure
Performance
Concentricity plays a very important part in 1.
Number of pieces per grind. 2. Accuracy of the
cavity.
Step Tool
Subland Tool
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Subland vs Step Drills Investigation Procedure
Performance
You will note that due to the eccentric Step tool
running in a bushing, the Step tool will run less
pieces per grind because Point B is higher than
Point A. The cutting action is distributed
unequally. As a result, Point B will break
down quicker. This same fly cutting action will
produce a rough and oversized cavity.
Step Tool
B
A
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Subland vs Step Drills Investigation Procedure
Performance
concentricity is the prime reason why a Subland
will consistently drill more holes between grinds
and attain greater cavity accuracy, because the
cutting load is distributed equally. Point C is
the same distance from the center line as Point
D.
Subland Tool
C
D