2.2.7 - CNC Router Operations

A step-by-step tutorial for Full-Sheet Machining.

Note

Target Audience This tutorial is for students using the PHS Stepcraft Q.408. CNC machining is “subtractive”—errors can break expensive bits or the machine itself. Always verify your toolpaths with an instructor before hitting Cycle Start.

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0. CAM & Post-Processing

Before heading to the machine, you must prepare your G-Code.

1. CAD Software: Create your 3D model in Onshape, Export as STEP File.
2. CAM Software: Import your model STEP File into Fusion 360.
3. Setup: Set your Work Home (WCS). For most PHS projects, this is the Top-Left-Front corner of the stock but sometimes is the center, just be sure you know what you have set for the machine preperation.
4. Toolpaths: Select appropriate bits (Endmills/Drills) You will be using in the project.
5. Post Process: Use the Stepcraft UCNC Post Processor. This is to talk to the machine you are using.
6. Verify: Use Simulation to check toolpath in Fusion, and have a mentor review the CAM before Exporting/Post Processing G-Code.
7. Editing After Processing, a window will load previewing the G-Code - You will need to edit this file and remove the X0 Y0 G53 Lines which are referencing a home positition that does not exist.
8. Transfer: Save the .nc file to a USB drive.

Screencap of the WCS orientation and Post-Process menu.

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1. Safety & Machine Inspection 🛡️

• Safety Glasses: Must be worn at all times when near the machine.
• Clear Path: Ensure the 4’x8’ gantry path is clear of bags, chairs, or people and any debris.
• E-Stop Check: Locate the physical E-Stop on the machine and the software stop.

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2. Machine Startup & Homing

1. Turn on the main Stepcraft power switch.
2. Launch the UCNC software on the control PC.
3. Reset the E-Stop in the software (click the flashing “Reset” button).
4. Press Home All. The machine will move to its mechanical limits to find “Machine Zero.”

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3. Workholding (The GOAT Board)

How we hold the material down is critical for accuracy.

• GOAT Board: Our custom fixturing system for smaller parts or aluminum.
• Mechanical Clamps: Use only if the toolpath stays at least 1” away from clamp locations.

Photo of the Vacuum Table zones or GOAT board setup.

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4. Tooling & Bit Changes

1. Select the collet that matches your bit diameter (typically 1/4” or 1/8”).
2. Clean the collet and nut of any dust.
3. Insert the bit so the flutes are NOT inside the collet (grip the shank only).
4. Tighten using the dual-wrench method. Do not over-tighten.

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5. Setting Work Home (Zeroing)

You must tell the machine where your material is located.

1. Jogging: Use the keyboard to move the bit to your stock’s Top-Left Corner.
2. Zero X/Y: Set these values to zero in UCNC.
3. Zero Z: Use the Touch Plate to find the exact top of the material. Use the TLS Button in the software.

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6. Feed & Speed Reference

Stepcraft Q.408 handles aluminum and wood differently. Reference this table before running:

Material	Tool	Spindle RPM	Feedrate (mm/min)	Max Depth (DOC)
Plywood	1/4” Upcut	15,000	1200	18mm (3/4”)
Aluminum	1/8” Single Flute	9,000	200	Full Depth/Trochoidal (0.01”)
Polycarbonate	1/4” O-Flute	12,000	700	6mm (1/4”)

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7. Run the Operation 🚀

1. Air Run: (Optional but Recommended) Run the code 20mm above the material to check for errors.
2. Dust Boot: Lower the dust boot to the material surface.
3. Start: Click Cycle Start. Keep one hand near the E-Stop for the first 30 seconds.

Danger

Router Height Restrictions Because this is a router and not a mill, the Z-height is limited. Ensure your retract height in Fusion 360 doesn’t cause the gantry to “top out” or hit a clamp.

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8. Cleanup & Teardown

• Wait for the spindle to come to a complete stop.
• Vacuum the entire 4’x8’ bed—dust in the tracks causes mechanical wear.
• Remove the bit and return it to the proper storage slot.
• Power down the controller if leaving overnight. (You may leave machine on if running more parts)

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Operation Workflow

graph TD
    A[Onshape Design] --> B[CAM Fusion Toolpaths]
    B --> C[Post Process to G-Code]
    C --> D[Turn Machine On / Home Machine]
    D --> E[Secure Workholding<br>Determine Workpiece Zero]
    E --> F[Insert Tool / Set Work Zero<br>Z TLS]
    F --> G[Execute Cut]

    G --> H{Tool Change<br>Required?}

    H -- Yes --> F
    H -- No --> I[Complete Job / Cleanup]