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Centroid Mill Operator Manual

If you’ve never used a CNC machine before, we recommend learning the basics on the X-Carve machine before using the 4×8.

Once you’ve made a simple project with it and learned the basics of CAD/CAM software, speeds and feeds, end mills, and toolpathing, follow the steps outlined in the training section below to get access to the 4×8 machine.


If you are new to CNC, we HIGHLY recommend you learn on the Shapeoko or X-Carve first.

To get signed off on the 4×8, attend a 1-on-1 training session with an authorized trainer. When you arrive at the training session, you will need to bring a project with a CAM design already prepared. The CAM file must have been created by you and not a third-party or downloaded file. You must be able to modify the file on site (bring a laptop, or if using VCarve Pro, you may use one of the CNC computers with VCarve Pro installed. To schedule a 1-on-1 session with a trainer, post a request on the CNC Slack channel or email [email protected] The certification form must be signed by you and the trainer for you to be signed off on the machine.

Training for manual operation only

If you are not running a program but operating the CNC manually (e.g. surfacing a board), you do not need a CAM design to get signed off to operate the machine. In this case, you will only be allowed to operate machine manually.

Safety Guidelines

  1. Stay clear of the moving gantry to avoid being struck.
  2. When cutting, the machine is loud enough to cause hearing damage. Wear hearing protection when the machine is running and cutting material.
  3. The router bit may throw chips and debris at high velocity. Always wear eye protection when the machine is cutting material.
  4. Double check your toolpaths to make sure the spindle does not crash into an object, causing damage to the machine.

Machine specifications

  • 1300 x 2500 x 200mm = 51.1811” x 98.4252” x 7.87402
Make and model Sequoyatec 1325
Controller Centroid Acorn
Work envelope 4' x 8' x 0.66’ (1300 x 2500 x 200mm)
Spindle power 3KW, water-cooled
Spindle speed 0-24000rpm
Transmission Rack and pinion for X and Y, ball screw for Z
Repeatability ±0.002“ (0.05mm)
Weight 1100kg


Tips for creating a toolpath file

Fusion 360

Ensure that your coordinate directions and origin point match the physical machine and your stock material

The CAM setup in Fusion 360 does not default to the same coordinate directions as the Sequoyatec. You will have to edit the manufacturing coordinate system in Fusion 360 to match the machine. In manufacture mode, right click on your setup definition and select Edit.

You have a few options in here. Whether you want your origin to be the material top, bottom, or something else, make sure what you select here matches how you intend to set it up on the machine.

:!: An unexpected setting for your model origin will at best cause the machine to mill through air, at worst plunge your tool through your workpiece and into the machine bed!

Post Processing

The most important setting is the Post Configuration. Use the following settings:

  • Vendor: CENTROID
  • Post: CENTROID / centroid

Defaults for the right-hand pane all work.

In more complex parts, it may be worth having multiple programs for a single complex part. This could be useful for example if you are concerned about crashing into your workpiece clamps. You could have one program that only cuts in a certain area, then another program that cuts elsewhere, switching clamp positions in between programs. In that case, you can select only the toolpaths you wish to post process for a given file.

Operating the machine

Starting up the machine


  1. If the E-stop button has been pressed, release the E-stop button by twisting the large E-stop button counter-clockwise until it pops up.
  2. Turn the power switch to the “on” position.
  3. Turn on the PC (if it is not already on) by pressing the power button on the computer.
  4. Log on to the PC using your CAD account.
  5. Run the CNC12 software (cncm.exe) using the shortcut on your desktop. It should automatically connect to the controller electronics.
    1. If you don't have this shortcut, create a new one by right-clicking the desktop and choosing New > Shortcut, then typing in the following as the location: C:/cncm/cncm.exe
  6. Reset the machine by pressing the large red “Press to Clear”.
    1. A green “Reset Cleared” message should appear in the command log.

NOTE: you should hear the machine make a noticeable “ka-chunk” noise when both the E-stop and power switch are engaged. This is just the transformer in the control box turning on.

Coolant Flow

The spindle is water cooled. To protect the spindle from overheating, coolant must be flowing while the spindle is in operation. To ensure coolant is flowing, check the flow indicator attached to the spindle. Do not start cutting material if coolant is not flowing.

Control Interface

The following is an overview of the control interface upon startup.

Current Position

The X,Y,Z coordinates of the cutting bit in relation to your work zero position. The work zero position should have been defined in CAM and must be set in CNC12 before running you program. If work zero is not set in CNC12, the controller will not know where your stock material is located, and a crash may occur.

Current Position (Machine coordinates)

The X,Y,Z coordinates of the spindle in relation to the Home Position of the machine. These coordinates do not depend on the location of your stock material and can only be set by homing the machine (Reset Home).

Spindle Control Panel

Spindle Control allows you to manually set the spindle speed. Normally, you do not need to use this panel because the program should control the spindle automatically.

Jog Panel

The Jog Panel is used to manually move the spindle. There are several circumstances in which you may need to jog the spindle:

  1. When setting the Work Zero position
  2. When doing a manual cut
  3. When moving the spindle or gantry out of the way to gain access to the some area of the table.

Cycle Start

Cycle Start begins the execution of the currently loaded GCode commands. The GCode commands to be executed may be

  1. The GCode program you loaded
  2. A single GCode command entered into the MDI interface
  3. The GCode program created by Intercon via the CAM control panel

Cycle Stop

Cycle Stop stop the execution of the GCode commands being executed.

Reset Home

When you home the machine (“Reset Home” button), it finds its home position by gradually jogging towards the limit switches until each homing switch is triggered.

  1. Home the machine by pressing the “Reset Home” button.
  2. You must reset home every time you start up the machine (after you have clicked “Reset”). You must also reset home if you crash the machine (because it will have lost its home position).
  3. The homing routine is slow, so if the spindle is far from the origin, it may save time to jog the spindle close to home position (the corner closest to the control cabinet) before starting the homing sequence.


Keyboard jogging is highly recommended because it seems more reliable and less likely to cause a crash due to buggy control execution.

To enable keyboard jogging and display the keyboard jogging shortcuts, press Alt-J. The following window appears:

You can close the cheat sheet while leaving keyboard jogging active by closing the window. Keyboard jogging remains active as long as Keyboard Jogging Active is displayed.

Installing Bit

The spindle uses a collet to hold the bit securely while the bit is cutting. The collet diameter must match the shank diameter of the bit exactly.

Set of collets

The Sequoyatec comes with the following collet sizes:

  • 1/8”
  • 1/4“
  • 1/2”
  • Various metric sizes

Make sure you are using the correct size collet for your shank or the bit will come lose while cutting, destroying the bit and the collet.

Follow these steps to install the bit:

  1. Make sure the collet, collet nut, and shank of the bit are clean and free of any dust or damage. If there is dust wedged between the mating surfaces when you tighten the collet nut, the bit may come loose during operation, destroying the collet and bit.
  2. Snap the collet into the collet nut at an angle. You should feel the collet snap into place.
  3. Lightly thread the collet nut with the collet onto the spindle. Do not tighten the nut until the bit is in the collet, or the shank of the bit won't fit into the tightened collet.
  4. Insert the bit into the collet.
  5. While holding the bit, tighten the collet nut by hand until the bit is held by the collet and does not fall out. Do not let the bit drop. Carbide is brittle and will chip when dropped.
  6. Finish tightening the collet with the two spindle wrenches. Make sure you use enough torque to prevent the bit from coming loose while cutting.

Setting X,Y Zero (Work Zero)

  1. Jog the bit to the X,Y zero position (as you defined in the CAM)
  2. Click “Set All Zero” in CNC12 to the current position to (0,0,0). Alternatively, click “Set Axis Zero” to set each axis one by one. Note: Even though we are setting the current Z position to 0 when executing “Set All Zero”, Z zero is set again in the next step (“Setting the Z Zero”). The reason for this is that it is sometimes difficult to accurately set X,Y, and Z zero simultaneously.
  3. When the bit is in the X,Y zero position, the X,Y coordinates in “Current Position” should be 0,0, as shown below:

Setting the Z Zero (Work Zero)

Setting the Z zero position can be done using the touch probe, or it can be done manually.

Setting Z Zero with the touch probe

Before setting Z Zero with the touch probe, check to make sure that the controller detects contact between the bit and the touch probe.

Press Alt-I on the keyboard to display inputs.

Touch and release the touch probe from the bit several times. Verify that Input 7 (touch-probe input) is toggling. This verifies that the touch probe is correctly sensing contact with the bit.

Press Alt-I again to exit out of the Input Display.

Setting Z Zero can be done before or after starting your program. Whenever there is a tool change in your program, including when you first run a program, the controller will prompt you to complete the Z zero touch-off sequence. You can skip the Z zero touch-off sequence in-program if you have already set Z zero out-of-program. In any case, follow the sequence below to touch off the bit to the Z plane.

  1. Jog the bit to a location above the point that you will use to set Z zero. In the image, the Z zero plane was defined in CAM as the top of the spoilboard. If Z zero was defined as the top of the stock, then the stock would need to be mounted first, with the touch probe resting atop the stock.
  2. Set the touch probe directly under the end mill.
    1. Note: the touch probe is connected to ground through wiring inside the machine, so no ground clip is needed.
  3. If performing Z zero out-of-program, run the M55 macro from the MDI console. Bring up the MDI console in CNC12 using the MDI button at the bottom, or by pressing F3.
  4. Follow the prompts that come up on the screen.

Setting Z zero without the touch probe

  1. Jog the bit down toward the Z-zero plane at a convenient location.
  2. Slide a piece of paper underneath the bit to indicate when the bit has reached the Z zero plane.
  3. When the bit is located at the Z-zero plane, click “Set Axis Zero” in CNC12 and follow the prompt to set Z to be zero at the current location of the bit.
TODO: Add images

Fixed Zero Positions

If you prefer not to set the X,Y Zero positions manually, there are two fixed X,Y zero positions you can use that are based on the machine coordinates. These X,Y zero positions can be set using the M56 command for the first zero position or the M57 command for the second zero position.

The first X,Y zero position (M56) is located at the bottom left corner of a hypothetical rectangular piece of stock abutted against 0.5“ dowel pins pressed inside pre-drilled holes in the spoilboard (see photo). To use this zero position:

  1. Make sure that you have defined X,Y zero in your CAM design to be the bottom left corner of your rectangular stock.
  2. Place the dowel pins into the predrilled locating holes.
  3. Place your rectangular stock material onto the spoilboard, with the edges of the stock butted up against the dowel pins. Do not force the stock against the dowel pin, or the predrilled holes will wear out over time. The dowel pins are to be used for locating only and not as clamps.
  4. Clamp your stock material down using your method of choice.
  5. Remove the dowel pins once the stock material is clamped to reduce the risk of cutting into the dowel pins.
  6. Execute the command M56 through the MDI interface or by clicking the M56 button (if you have not done so already).

The second X,Y zero position (M57) is located at the bottom left corner of the spoilboard (see photo). To use this zero position, simply:

  1. Make sure that you have defined X,Y zero in your CAM design to be the bottom left corner of your rectangular stock.
  2. Align your stock to be flush with the left and bottom edges of the spoilboard.
  3. Clamp your stock material using your method of choice.
  4. Execute the command M57 through the MDI interface or by clicking the M57 button (if you have not done so already).

Note about accuracy The fixed zero locations are set relative to machine coordinates. Since machine coordinates are reset every time the machine is homed, the machine coordinates (and therefore the fixed zero locations) can deviate from session to session, depending on the repeatability of the homing switches. In addition, since the fixed zero positions are machined into the spoilboard, the positions can shift if the spoilboard shifts. For these reasons, you are not going to get as accurate a zero position using M56 or M57 as you can by setting the X,Y zero positions manually.

Securing your material with clamps

There are a couple of sets of steel clamps you can use to secure your stock to the spoilboard. A minimum of 2 clamps are required to hold down a single piece of stock. Note that steel is a hard material, so you should always check your toolpaths to ensure the clamps are not struck by the bit, spindle, or dust shoe. When in doubt, it is safer to use double-sided tape.

Here is an example of steel clamps being used to secure a sheet of plywood onto the spoilboard:

Here is a close-up of a single clamp being tightened with a thumb screw:

Running a toolpath file

To load the program, click Load from the CNC12 menu, and open your GCode file.

A graph will be displayed showing a trace of the program tool path. Verify that the tool path is correct.

After you load a tool, CNC12 will prompt you to begin the procedure of setting Z zero. If you have already set Z zero, you can skip this step by entering 0 (“Continue without resetting Z0”).

Turn on the dust collection as explained in Activating the dust collection system After Z zero is set, when you click Cycle Start, the program will begin. Note: At this point, be prepared to shut down the program (Cycle Stop) in case you made a mistake in CAM or in setup that would result in a crash.

Consider doing an air cut prior to actually cutting material. To perform an air cut, set Z zero to be above your actual Z zero, so the bit will hover above the stock without actually cutting anything. When you have verified the program with the air cut, restart the program with the correct Z zero.

Activating the dust collection system

  1. Slide the dust shoe onto the spindle mount.
  2. Clip the dust shoe on.
  3. Set the height of the dust shoe so the bristles are at the same Z height as the tip of the bit. If extra clearance of the dust shoe is required, raise the dust shoe above the height of the bit. Note: If the dust shoe is above the height of the bit, the suction may underperform, allowing dust to escape the dust shoe.
  4. Turn on the dust collector using the remote.

With the shoe cover installed, the dust shoe can also be used to vacuum up the table.

Shutting down the machine

  1. Return the machine to the home position using the G28 command as a courtesy to the next person who uses the machine.
  2. Exit the CNC12 software.
  3. Log off the PC.
  4. Turn off the controller electronics by turning the key lock to the “off” position.
  5. Vacuum any debris off the machine.
  6. Turn off the dust collector using the remote.
  7. Sweep up debris from the floor, if necessary.
  8. Don't forget to log your time on the timesheet!

Retrofit documentation

When the CNC machine first arrived, it came with a controller board and software that was a bit limiting and confusing. Robert Payne volunteered his time to replace this board and software using the Centroid Acorn platform, a process which he documented thoroughly here:

Controller cabinet documentation

System diagram

Use this diagram to understand the relationships between each component to help with troubleshooting. See the components section below for detailed pinouts for each component.

Cabinet photos

Front side Back side

Front side close-ups

Back side close-ups


Incoming 240VAC terminal block

Connects the wires from the 240VAC plug to the components inside the cabinet.

Make/model or part no. N/A
Manual and/or datasheet N/A
Wiring diagram

Residual current circuit breaker

Turns off all power when there is too much current (>30mA) running through the cabinet itself.

Make/model or part no. DZ47LE-32 C32
Manual and/or datasheet
Wiring diagram

Thermal overload relay

Turns off all power when the 240VAC wires get too hot.

Make/model or part no. Shern Dian RA-30
Manual and/or datasheet
Wiring diagram


Turns off all power when more than 32A of current is detected in the 240VAC lines.

Make/model or part no. RT28N-32X
Manual and/or datasheet Datasheet
Wiring diagram

240VAC distribution block

Splits the protected 240VAC lines to power other subsystems.

Make/model or part no. N/A
Manual and/or datasheet N/A
Wiring diagram

EMI filter

Helps protect the VFD by filtering out noise in the 240VAC lines.

Make/model or part no. ZONL ZJ2AC-20A
Manual and/or datasheet
Wiring diagram


Safely controls the speed of the spindle using command signals sent from the Acorn board.

Make/model or part no. Best FC300-3.0G-3S-B4CF
Manual and/or datasheet Manual
Wiring diagram

Stepper motor transformer

Converts 240VAC to 70VAC for the stepper motors.

Make/model or part no. FDK-800VA
Manual and/or datasheet N/A
Wiring diagram

Stepper motor drivers

Controls the movement of the stepper motors based on low-voltage signals supplied by the Acorn controller board.

Make/model or part no. Leadshine DMA860H
Manual and/or datasheet Datasheet
Wiring diagram

Acorn board

Interprets G-code from the PC and produces electrical signals to control various parts of the machine.

Make/model or part no. Centroid CNC Acorn
Manual and/or datasheet
Wiring diagram

Acorn power supply

Converts 240VAC into both 24VDC and 5VDC to power the Acorn board and 5V logic of the stepper drivers.

Make/model or part no. Mean Well RD-35B
Manual and/or datasheet Datasheet
Wiring diagram

Acorn relay board

Allows control of ??? through the Acorn board using G-code commands.

Make/model or part no. N/A
Manual and/or datasheet N/A
Wiring diagram

Wiring harness terminal block

Connects all of the various sub-systems to the giant cable that goes to the machine.

Make/model or part no. N/A
Manual and/or datasheet N/A
Wiring diagram
Pin mappings
  • 1 = X axis stepper driver - A+
  • 2 = X axis stepper driver - A-
  • 3 = X axis stepper driver - B+
  • 4 = X axis stepper driver - B-
  • 5 = Y axis stepper driver - A+
  • 6 = Y1 axis stepper driver - A-
  • 7 = Y1 axis stepper driver - B+
  • 8 = Y1 axis stepper driver - B-
  • 9 = Y2 axis stepper driver - A+
  • 10 = Y2 axis stepper driver - A-
  • 11 = Y2 axis stepper driver - B+
  • 12 = Y2 axis stepper driver - B-
  • 13 = Z axis stepper driver - A+
  • 14 = Z axis stepper driver - A-
  • 15 = Z axis stepper driver - B+
  • 16 = Z axis stepper driver - B-
  • 17 = Acorn board pin IN1 - X limit switch signal
  • 18 = Acorn board pin IN2 - Y limit switch signal
  • 19 = Acorn board pin IN3 - Z limit switch signal
  • 20 = Acorn board pin +24 IN
  • 21 = UNKNOWN
  • 22 = VFD - U
  • 23 = VFD - V
  • 24 = VFD - W
  • 25 = Incoming 240VAC terminal block - ground
  • 26 = Acorn board pin IN7 - touch probe signal
documentation/cnc_routers/sequoyatec1325.txt · Last modified: 2022/05/01 17:49 by shchang