Seattle Ultrasonics · Assisted Sharpening

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    Seattle Ultrasonics · Assisted Sharpening

    Private beta

    This is a pre-release build for invited testers. Enter the beta password to continue.

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    Seattle Ultrasonics · Assisted Sharpening

    Before you start

    End User License Agreement

    Seattle Ultrasonics Assisted Sharpening

    Disconnect from the knife?

    Connect your knifeDone

    Pair with the C-200 over Bluetooth. While connected, the ultrasonics stay off — pressing the handle button won't run the blade.

    Remove & re-insert the battery

    First, put the knife in pairing mode: remove the battery, then re-insert it. Click Connect within 30 seconds of the battery going back in.

    Animation of the browser's Bluetooth window: C-200 appears in the list, is selected, then the Pair button is clicked.
    Then pick C-200 from the list and press Pair
    Update your knifeDone

    Checking for firmware updates…

    Firmware

    —

    Required

    Preparing…

    Keep this page open and the knife nearby until the update finishes.

    Zero on the stoneDone

    Lay the knife on its side so the handle sits flat on the stone. Then press and hold the handle button for about a second, and release to set the zero position.

    Knife laid on its side with the handle resting flat on the sharpening stone
    Handle flat on the stone
    Live roll—°Waiting for button…
    Choose your edge angleDone

    The C-200 ships with a 13° factory edge. A smaller angle is sharper but less durable; a larger angle is more durable but less sharp.

    13.0° / side
    Factory angle
    ← Sharper, less durableMore durable, less sharp →
    SHARPENING STONE
    Edge cross-section · closeup26° total included angle
    Sharpen

    Sharpen using even pressure across the blade, making use of as much of the stone surface as possible.

    Target ±13.0°
    Side ASide B
    0.0°
    Lift the blade toward 13°
    Δ —
    Stroke motionIn air
    Side A0 cm Side B0 cm
    ✓Session results

    —

    —

    13°target / side

    Stroke motion by angle

    — on-angle

    stroke motion on angle

    Sharpening time—active sharpening
    Total stroke—both sides
    Side A——
    Side B——

    Seattle Ultrasonics · C-200

    © 2026 Seattle Ultrasonics · License agreement ·

    Settings

    Guide

    Preferences are saved on this device and persist between sessions.

    Pro modeTighter target (±1.0°), 0.1° increments, and the stroke-distance readouts.
    Angle precisionIncrement for the angle picker and the live readout.
    Tolerance zoneHow far off angle still counts as “on angle” — the green band.
    Sound mode—
    Sound only on stoneStay quiet while the blade is off the stone.
    Read angle only on stoneFreeze the angle readout and knife LEDs while the blade is in the air.
    Show movement tracerThe small stroke-path canvas on the sharpening screen.
    Show stone detectionThe “On stone / In air” chip. Detection keeps running either way.
    Keep screen awakeHold the display on while you're connected to the knife.

    Privacy

    Your browser is sending a Global Privacy Control signal, so we’ve turned this off. You can turn it back on if you want to.

    Send session dataSends your completed sessions — motion data, angles, and device details — to Seattle Ultrasonics so we can improve the sharpening guidance. Your on-screen guidance is calculated on your own device and works the same either way. Read the EULA

    Diagnostics

    Export the session that just finished, or load a recorded session (JSON) to replay its IMU stream through the full experience.

    cloud: —

    No file loaded.

    accel: —

    gyro: —

    roll: —

    stream: —

    knife: —

    contact: —

    Ground truth: hold the HANDLE BUTTON (or SPACE) while the blade is truly on the stone.

    Console