milling machine cutting metal piece

Vertical Milling Machines vs. Horizontal: Differences Explained

Manual and CNC milling in today’s metal fabrication is crucial in shaping workpieces into high-precision components. Skilled machinists use these processes to cut and shape materials, employing a vertical or horizontal milling machine.

End mills or other cutters secured in the milling head meticulously remove material from the workpiece. Unlike a metal lathe machine, where the part spins and the cutting tool remains fixed, a rotating spindle carries the cutting tool in milling machines. Concurrently, clamps or vises secure the workpiece on the worktable.

The spindle on the vertical milling machine maneuvers vertically along one or two axes, often offering variable, high-speed settings. Depending on the mill type, the worktable may incorporate a power feed, typically for longitudinal movement, and can be fitted with a digital readout (DRO) to avoid relying on dials and to ensure precise dimensioning. A work light for optimal vision and safety and a coolant system are also standard features on many milling machines. Sometimes machine shops will add a rotary table for a 4th axis on milling machines without CNC controls.

While both vertical and horizontal milling machines perform similar operations, these categories differ in production processes. Nevertheless, the vertical milling machine proves to be more versatile in handling various tasks.

Here are ten fundamental differences between horizontal milling machines and vertical milling machines and a brief explanation of each.

1. Orientation of the Spindle

As the name of each suggests, horizontal machining centers have a horizontal spindle running parallel to the worktable’s surface. The machine’s cutting tool removes material from the workpiece while rotating about this horizontal axis.

On vertical machining centers, a vertical head runs perpendicular to the worktable’s surface, and the cutting tool rotates in a vertical spindle to remove material from the workpiece. Although durability and precision are the hallmarks of both milling styles, most agree that horizontal mills are preferable for heavy-duty applications, but, as mentioned, vertical mills are much more versatile.

2. Tool Geometry

The shape and specifications of milling cutters and cutting tools for the two types of milling machines are different. Horizontal milling machines feature shorter and thicker tools capable of taking deeper cuts and removing more material than vertical milling machines.

Vertical milling machines often use long cylindrical tools called end mills or dovetail cutters for more precise but shallower cuts on smaller workpieces.

3. Cutting Specifications and Accuracy

The cutting tool’s geometry directly affects its cutting specifications and results. Because they are shorter and thicker, horizontal tools have the stability to sustain them during deep, heavy cuts. On the other hand, vertical tooling cannot produce deeper cuts because they will vibrate, affecting the accuracy of the cut and sometimes breaking.

4. Versatility

Vertical milling machines win the prize for versatility. Machinists use them as boring mills, but they can quickly transform into a variable-speed drill press, which is an awkward operation on a horizontal mill. Both machines can face and slot, but the vertical mill is more adept at prototyping, custom work, and engraving.

5. Cost of the Machine

The initial cost of vertical milling machines is typically less than a horizontal milling machine, as is the expense of operation and maintenance, making them the more popular choice between the two, especially among small shops. More machine operators are familiar with vertical machines, making them easier and less expensive to operate than horizontal models.

6. Material Removal Rate

Because they are more stable and can produce deeper cuts, horizontal milling machines have a much higher material removal rate than vertical mills. Machinists typically prefer vertical milling machines for operations such as facing and grooving because the cuts are not as deep and they are precise. But this limited cutting potential results in a lower removal rate for the vertical mill.

7. Overarm and Arbor Support

The horizontal milling machine has two elements not present in a vertical mill: an overarm and an arbor support. The overarm is a horizontal beam at the top of the column. Depending on the type of machining needed, horizontal mills may hold either a cutting tool or an arbor. If the arbor is used for a specific kind of milling, it requires an arbor support to align the arbor and provide support. Arbor supports are fastened to the overarm. Both of these parts are peculiar to the horizontal mill.

8. Number of Sides for Machining

The horizontal milling machines allow the operator to approach the workpiece at several angles and sides, while the vertical milling machine works on a single plane. Also, the horizontal mill is better suited for customizable jobs since specific add-ons and features for the horizontal setup are not available on a vertical mill.

9. Chip Evacuation

During machining, the metal chips that are produced tend to remain on the vertical mill’s workpiece surface, melting and causing flaws that could require post-processing. Horizontal cutters throw the chips away from the work table and toward the floor, leaving a better-machined finish.

10. Finding Trained Operators

In addition to the high initial, operating, and maintenance costs, another difference between the two types of mills is finding trained operators with experience and expertise in the horizontal milling machine. Because these machines are scarce, only a few machinists have hands-on experience with them.

What is a Vertical Milling Machine?

Vertical milling machines are a common sight in machine shops. As the name suggests, these machines feature a cutting head or spindle that is vertically oriented. The spindle holds the cutting tool used to machine the workpiece. Some machines have a quill that moves the spindle along the Z-axis. Additionally, the worktable can move along the X-axis, Y-axis, and on some machines, up and down on the Z-axis.

The vertical milling machine can also function as a drill press when the quill moves vertically on the Z-axis. These machines are handy for projects where the work is on a single side, such as sectioning operations or finishing operations like beveling. There are two vertical milling machines: knee mills (also known as Bridgeport-type or turret milling machines) and bed milling machines (commonly referred to as bed mills). Each type functions differently, offering unique advantages.

Machinists have various tools at their disposal, depending on the type of cut and material. Cutting tools can be held in the collet or directly in the milling head, and the milling head moves into the workpiece as the cutting tool spins.

In addition to milling, drills and taps can be used to create holes and internal threads. Various end mills and cutting tools are available for machining materials ranging from aluminum to titanium.

With these machines and tools, machinists are equipped to handle diverse machining tasks with precision and efficiency.

Knee Mill: The machine tool of choice for many machine shops, knee mills feature a fixed spindle. The knee moves vertically on the Z-axis, and the table moves on a longitudinal X-axis and an in-and-out Y-axis. As mentioned earlier, the rotating spindle inside the quill provides another Z-axis.

Today, many CNC mills are knee mills, and their versatility is enhanced as either a stand-alone or benchtop model. Depending on their table size, a variable-speed vertical mill has an almost infinite amount of machining uses. Many knee mills have an R8 spindle taper and a drawbar to hold collets. They are available in a single phase for home shops and hobbyists, perfect for those home machinists with one machine tool and a bandsaw to manufacture small parts. And for those parts requiring angle cuts, the milling head swivels left and right 90 degrees.

Bed Mill: The bed mill’s table does not move up and down along the Z-axis. Instead, vertical movement comes from the spindle. Unlike the knee mill, where the quill moves but not the motor, the entire head and motor of the bed mill move up and down on the Z-axis. But just like the knee mill, the bed mill’s work table travels along the X-axis and Y-axis.

Bed mills work well when large and heavy workpieces must be machined.

What are Vertical Milling Machines Used For?

Because of their versatility, vertical milling machines are at home in practically any industry. The vertical knee mill is even sometimes referred to as a “mill drill” because it can perform milling and drilling operations. Here is a handful of the many components and products that come from vertical milling machines and the industries using them:

  • An excellent choice for manufacturing automotive parts since shafts, gears, pins, etc., require several vertical milling operations.
  • The transportation industry relies on parts produced by the CNC vertical milling machine. Many of these components help keep their products and personnel safe during transportation
  • Agriculture depends on vertical CNC mills to make parts like livestock gates and various farm equipment components.
  • Vertical CNC milling machines can face, slot, drill, and bore, making them invaluable in manufacturing industry-specific machinery and tooling used in many manufacturing processes.
  • Excellent for prototyping, custom work, toolroom tasks, or engraving, and, in a pinch, they can help out with woodworking jobs.
  • Vertical CNC mills, with their variable spindle speeds and other features, can complete simple and complex metalworking projects and can even be used as a router to machine large, flat plates in various industries
  • It’s so versatile that vocational schools and science labs purchase them as a valuable teaching tool for students to understand the milling process

What is a Horizontal Milling Machine?

Like vertical mills, horizontal milling machines feature a rotating spindle. Still, this spindle is mounted horizontally. The cutting tools used on these machine tools are typically shorter and thicker, often similar to the grinder wheel, instead of the long, thin-end mills you would see on a vertical milling machine.

While not nearly as versatile as a CNC vertical knee mill, horizontal mills are capable of taking heavier and deeper cuts. The motors on these machines often have more horsepower to move the larger beds and the heavy-duty workpieces.

What are Horizontal Milling Machines Used For?

Horizontal milling machines are primarily used in the following types of machining operations:

  • Machining grooves on a workpiece
  • Machining slots
  • Multi-side face milling operations
  • Machining jobs with extremely heavy workpieces and challenging material
  • Horizontal milling machines are an excellent choice for specific complex projects, such as manufacturing scalpels and diagnostic imaging equipment for the medical industry.
  • Drilling, tapping, and boring on the horizontal plane.

Choosing between Vertical and Horizontal

Both milling machines may have their merits, but for overall versatility, reliability, and affordability, the vertical milling machine will always come out ahead. Unless your company has specific needs, such as machining large, bulky, or heavy items, the choice is clear. You can use the vertical milling machine for so much more: high-volume production jobs, repair work, tool and die, metal patterns, engraving, and the list goes on!

Adding Precision Computer Numerical Control (CNC) to the Vertical Milling Machine

A computer numerically controlled (CNC) mill can produce high-quality parts with minimal operator involvement. This advanced machine utilizes special motors and precise measuring tools (stepping motors) to select the tools, move the table and head, and machine the parts according to exact and repeatable dimensions. For instance, the CNC Supra Vertical Knee Mill can efficiently create complex components that would otherwise be too time-consuming for manual milling.

The successful machining of parts on a CNC mill relies on the expertise of a skilled CNC machinist or programmer. By interpreting drawings and following the correct sequence of operations, these professionals can transform raw materials into precision parts that meet acceptable tolerances.

G-code programming is the foundation for CNC machining, and machinists trained in this language establish the appropriate sequence for CNC machines. Additionally, operators without extensive programming knowledge can quickly familiarize themselves with user-friendly CAM software, allowing them to edit existing programs or create basic programs.

In summary, the integration of CNC technology revolutionizes the manufacturing process by streamlining operations, enhancing precision, and enabling efficient production of intricate parts.

The CNC Supra Vertical Knee Mill

No CNC vertical milling machine takes on more work than the CNC Supra Vertical Knee Mill from CNC Masters. The Supra works equally well in the largest fabrication and machine shops. It also provides unmatched benefits to any small or mid-sized manufacturing company looking for a machine tool that can perform many functions without taking up lots of valuable floor space.

This versatile CNC mill with DRO is ideal for hobbyists, machine shops of all sizes, product development, high production work, engraving, and teaching tools in vocational-technical schools and science labs.

Look at a few of the specifications for the heavy-duty CNC SUPRA 10×54 Vertical Knee Mill:

  • Table travel (Longitudinal X-axis): 35.5”
  • Saddle travel (Y-axis): 15.5”
  • Knee travel (Z-axis): 18”
  • Table size: 10” x 54”

The Supra is a rugged machine tool made in the U.S.A. and backed by a one-year warranty with unlimited tech support. Check out the rest of the specs and features here, then call us at 626-962-9300 or email us at Contact us for an appointment and visit our facility in Irwindale, CA.

About Peter Jacobs

Peter Jacobs is the Senior Director of Marketing at CNC Masters, a leading supplier of CNC mills, milling machines, and CNC lathes. He is actively involved in manufacturing processes and regularly contributes his insights for various blogs in CNC machining, 3D printing, rapid tooling, injection molding, metal casting, and manufacturing in general. You can connect with him on his LinkedIn.

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29. Create a Peck Drilling Program in Circular or Rectangular Patterns
Using the Circular or Rectangular Drilling Wizards, you can program the machine to drill an un-limited series of holes along the X and Y planes. Program it to drill straight through to your total depth, use a high-speed pecking cycle, or deep hole pecking cycle. You can program the cut-in depth and return point for a controlled peck drill application to maximize chip clearance.

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20. Change up to 30 tools with compensation, and store your tool offsets for other programs
The MX supports…

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21. Use the optional ATC rack up to 8 tools for milling, drilling, and rigid tapping applications
The CNC Masters Automatic Tool Changer Rack and Tools (US Patent 9,827,640B2) can be added to any CNC Masters Milling Machine built with the rigid tapping encoder option. The tutorial will guide you through the set-up procedure using the ATC tools.

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22. Use the optional Rigid Tapping Wizard without the need for tapping head attachments
When you order your CNC Masters machine, have it built with the optional rigid tapping encoder. You can take any drill cycle program and replace the top line with a tapping code created by the wizard to tap your series of holes up to 1/2” in diameter.

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23. Use the optional Digital Probe to scan the profile and/or pockets of your fun/hobby type designs to write your tool path program and machine out a duplicate of your original design To “surface” scan an object, you can program the probe along the X or Y plane. The stylus will travel over the part starting on the left side front corner of the object and work its way to the end of the part on the right side. Depending on how the stylus moves, it will record linear and interpolated movements along the X, Y, and Z planes directly on the MX Editor.
To “pocket” scan an object containing a closed pocket such as circles or squares, the scan will start from the top front, work its way inside of the pocket, and scan the entire perimeter of the pocket.
Under the Setup of the MX software you will find the Probe Tab which will allow you to calibrate and program your probe. Your “Probe Step”, “Feed”, and “Data Filter” can also be changed on the fly while the probe is in the middle of scanning your object.

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24. Use work offsets G54-G59 for nesting applications
The work offsets offer you a way to program up to six different machining locations. It’s like having multiple 0.0 locations for different parts. This is very useful especially when using sub-routines/nesting applications.

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25. Create a Rectangular Pocket / Slot with our selection of Wizards to help you build a tool path program
The Cycle Wizards for the mill or lathe makes it easy to create a simple tool path without needing to use a CAD and CAM software.
On this Wizard, the Rectangular Pocket / Slots, can be used to form a deep rectangular pocket into your material or machine a slot duplicating as many passes needed to its total depth.

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26. Create a Circular Pocket Wizard
Input the total diameter, the step down, and total depth and the code will be generated.

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27. Do Thread Milling using a single point cutter Wizard

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28. Cut a gear out using the Cut Gear Wizard with the optional Fourth Axis

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19. Disable the axis motors to manually hand crank each axis into place
Easily de-energize the axis motors by clicking [Disable Motors] to crank each axis by hand, and then press [Reset Control] to re-energize the axis motors.

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30. The MX interface can easily be interchanged from Mill Mode to Lathe Mode
Use this interface for your CNC Masters Lathe. It contains all the same user-friendly features and functions that comes in Mill Mode. Simply go to the Setup page and change the interface.

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31. Use Tool Change Compensation or the optional Auto Tool Changer Turret if your application requires more than one tool in a single program
You can offset the length and angle of each tool and record it under Tools in your Setup. The program will automatically pause the lathe’s movement and spindle allowing you to change out your tool, or allowing the optional ATC Turret to quickly turn to its next tool and continue machining.
On the MX interface, you also have four Tool Position buttons. Select your desired T position, and the auto tool post will quickly turn and lock itself to that position.

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32. Use the Lathe Wizard Threading Cycle to help you program your lathe’s internal or external threads in inches or metric

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33. Use the Lathe Wizard Turning / Boring Cycle to help you program simple turning and boring cycles without having to go through a CAM or writing a long program with multiple passes

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34. Use the Lathe Wizard Peck Drilling Cycle to help you program your drill applications or for face grooving

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35. Facing / Grooving / Part Off Cycle Wizards – with Constant Surface Speed
These cycles can be used with Constant Surface Speed allowing the spindle speed to increase automatically as the diameter of the part decreases giving your application a consistent workpiece finish. With CSS built into the wizard, there is no need to break down the cycle into multiple paths and multiple spindle speed changes.

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36. This is our list of supported G and M codes which can be found under Tools > G Code/ M Code List in the MX
If you plan to use a third-party CAM software to generate your tool path program, use a generic FANUC post processor and edit it to match our list of codes. As an option, we also sell Visual mill/turn CAM software which comes with a guaranteed post processor for our machines to easily generate your tool path programs based on your CAD drawings.

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37. Our pledge to you…

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10. Run each tool path independently to study its movement
1. Run the machine on Trace mode. You can run each tool path independently, one line at a time to study the tool path movement on the machine to verify the position of the application and if any fixture/vise is in the way of the cutter’s path.

2. You can also verify your program by clicking on the Trace and Draw buttons together. This will allow you to view each tool path independently one line at a time in the Draw Window.

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2. Clutter Free Interface
The MX is engineered for the CNC MASTERS machine so you do not have to fiddle with a detailed complicated configuration that can be overwhelming. Just load in the MX and start machining!2. Clutter Free Interface
The MX is engineered for the CNC MASTERS machine so you do not have to fiddle with a detailed complicated configuration that can be overwhelming. Just load in the MX and start machining!

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3. Features Tour and Tutorials Included
The Features Tour will give you a quick run-down on all the features the MX can do for you. The Tutorials are easy to follow even for the first time CNC machinist.
Feel free to download the MX on any of your computers. We recommend downloading the MX along with your CAD and CAM software there at the comfort of your office computer to generate your tool path programs. You don’t need to be hooked up to the machine either to test your program in simulation mode.

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4. Navigate and Edit Your Program through the MX interface with Ease
With a few clicks of the mouse or using touch screen technology, you can easily navigate through the MX interface importing saved programs into the Editor from the File drop down menu. Using standard windows features to edit your program you can then lock the Editor Screen to avoid accidental editing, and if you need to insert a line in the middle of a program, just click on [ReNum] to re-number your tool path list.
You can create a program or import CAM generated G-code tool paths into the Editor
The X Y and Z W arrow jog buttons are displayed from the point of view of the cutter to avoid confusion when the table and saddle are moving. You can also adjust your spindle speed and coolant control while jogging each axis.

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5. Feed Hold – Pause in the Middle of your Program
Feed Hold lets you pause in the middle of a program. From there you can step through your program one line at time while opting to shut the spindle off and then resume your program.
You can also write PAUSE in the middle of your program and jog each axis independently while your program is in pause mode.

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6. Hot Keys
Hot Keys is an alternative method to easily control your machine using your hard or touch screen keyboard. One can press P to pause a program, press S to turn Spindle On, G to run a program, Space Bar to Stop, J to record your individual movements one line at a time to create a program in teach mode.

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7. Pick Menu – for conversational mode programming
Write FANUC style G-codes directly into the Editor or select commands off the [Pick] menu and write your tool path program in conversational mode such as what is written in the Editor box. You can even mix between conversation commands and G-codes in the same program.

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8. Pick Menu List of Options
Use commands such as MOVE, SPINDLE ON/OFF, COOLANT ON/OFF, PAUSE, DELAY, GO HOME…. to write your tool path programs in conversational mode.

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9. Draw the Tool Path to verify it before pressing Go
Hit Draw to view your tool path program drawing, check out its run time, or even simulate the tool path in 3D mode. This can be helpful to quickly verify your program before running it. You can also slow down or speed up the drawing or simulation process.
You can also hit Go within the Draw Window itself to verify the cutter’s position on the machine. The current tool path will be highlighted and simultaneously draw out the next path so you can verify what the cutter will be doing next on the program.

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MX Software – Easy to Use, Easy to Learn – Included with your machine purchase
The MX software is designed to work seamlessly with your CNC Masters machine. It is made to work with Windows PC – desktop, laptop, or an all in one – on standard USB. Use it on Windows 8 or 10 64-bit operating systems.
No internal conversion printer/serial port to USB software or additional conversion hardware is used with the MX.

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11. Counters display in Inches or Millimeters – Continuous Feed
1. When running a program, the counters will display a “real-time” readout while the machine is in CNC operation without counting ahead of the movement.
2. The current tool path is highlighted while the machine is in operation without causing slight interruptions/pauses as the software feeds the tool path to the machine. The MX internally interprets a program ten lines ahead to allow for “continuous machining” avoiding slight interruptions as the machine waits for its next tool path command.
3. “Run Time” tells you how long it takes to run your tool path program.

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12. Use the “Go From Line” command to start in the middle of your program
If you ever need to begin your program from somewhere in the middle of it, use [Go From Line] which you can find under Tools. The Help guide will walk you through how to position the cutter without losing its position on the machine.

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13. Exact Motion Distance without over-stepping on an axis while jogging
Use “Relative ON” to enter a specific coordinate to jog any of your axes to an exact location without having to write a program. It’s like using “power feed” but easier. You can jog an exact distance on any of the axes without needing to keep the key pressed down and mistakenly over-step the movement releasing your finger too slowly off the jog button.
Let’s say you need to drill a hole exactly 0.525” using the Z. So you enter 0.525 in the Z box. Next, adjust the JOG FEED RATE slider for the desired feed rate. Then “click once” on the +Z or -Z button to activate the travel. In this case you click once the -Z button first to drill the hole exactly 0.525”. Then click once on the +Z button to drive the axis back up 0.525”.

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14. Teach Mode – Jog Input
You can create a tool path program by storing each point-to-point movement by simply jogging an axis one at a time. Click on either of the Jog Input buttons to store each movement on the Editor Screen. You can then add Spindle ON, feed commands, and press GO to run the new program as needed. This is a great feature to help you learn to create a program by the movements you make on the machine without necessarily writing out an entire program first.

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15. Override on the fly to adjust the Jog Feed to Rapid or the Spindle Speed during the middle of a program
1. Jog Feed and Rapid with Override: You can adjust feeds using the slider from slow minimum 0.1″ per minute to a rapid of 100″ per minute of travel. You can even micro-step your jog as low as 0.01”/min. The [-][+] buttons allow you to fine tune feeds in 5% increments while the program is in motion.
2. Spindle Speed with Override: You can adjust speeds using the slider from a slow minimum RPM to the max RPM according to the machine setup. The [-][+] buttons allow you to fine tune feeds in 5% increments while the program is in motion.

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16. Adjust Counters using Pre-Set if you cannot begin the program from 0.00
In a situation where you cannot begin your cutter at it’s 0.00 location, you can “Pre-Set” directly into the counters by typing in your beginning coordinate. You can press Go from here to run your program. You can also “zero all” or “zero” your counters independently. With one click of the [Return to 0.0] button, all axes will travel back to its respective 0.0 on the machine.

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17. Set and Save your 0.00 position for future runs
Set and save your 0.00 position on the machine. These coordinates will be recorded as the first line of the program in the Editor Screen. Should you desire to return to this program at a later date, you only have to click on the Set Zero Return button. This will command the machine to automatically jog each axis to its saved “set” 0.00 position according to the recorded coordinates at the first line of the program.

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18. Create a “Home” position to clear your application and run multiple times
Let’s say you need to machine one application times 100 pieces. This usually requires a jig to retain that physical 0.00 position. But in this case, you want the program to end with a clearance of the axes to easily switch out the next piece of stock and start again. With Save Home, you have the ability to save this offset (home) position while still retaining your Set Zero position where the machine will mill your part out. Pressing [Save Home] will record this new position under the Set Zero line in your program.
Pressing [Go Home] will jog your axes back to your “saved home” position where you originally pressed the Save Home command. You can also input GO_HOME from the Pick Menu as its own tool path in your program. At the completion of your program the axes will end at your Home position. Replace your part, then press [Return to 0.0] button to allow the axes to return to its zero position, and press Go to start your next run.

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