The sharpening angle directly determines the balance between sharpness and durability. A lower angle (10–15°) creates a thinner, sharper edge ideal for precise slicing but more prone to chipping. A higher angle (20–30°) produces a robust edge that withstands heavy use but cuts less efficiently. Using the wrong angle can lead to premature dulling, edge rolling, or even permanent blade damage. Consistent angle control is the #1 skill separating pro sharpeners from beginners.

Step 1: Set your target angle using the presets or slider (e.g., 17° for a chef's knife).
Step 2: Observe the visual reference on screen — the dashed line shows your target, the solid line shows current angle.
Step 3: Place your phone flat on the work surface near your stone and optionally enable the gyro sensor to get real-time tilt feedback.
Step 4: Hold your knife at the displayed angle against the stone, using the visual as a mental reference. Practice until muscle memory kicks in.
Pro tip: Place your phone in a ziplock bag to protect it from stone dust and water spray.

For most EDC (everyday carry) folding knives, a 20–25° per side angle is recommended. This provides excellent edge retention for tasks like opening packages, cutting rope, or whittling wood. If your pocket knife uses high-end steel (e.g., S30V, M390, MagnaCut), you can go as low as 17° for superior slicing performance without significant chipping risk. For softer steels like 420HC or AUS-8, stick to 22°+ to prevent edge deformation.

There are several low-tech methods to estimate sharpening angle:
• The Coin Trick: A US quarter is about 1.75mm thick — stacking 2–3 quarters under the spine of a typical chef's knife on a flat stone approximates 15–17°.
• The Thumb Method: Place your thumb on the spine of the blade; the gap between your knuckle and the stone surface roughly corresponds to 20° for average hand sizes.
• The Matchbook Trick: A standard matchbook cover folded in half creates roughly a 15° wedge when placed under the spine.
• Marker Test: Color the edge bevel with a permanent marker, make one light pass on the stone, and check where the marker is removed — adjust angle until removal is even across the bevel.

Generally, maintain the same angle across all grits. The angle determines the edge geometry, not the finish. However, some advanced sharpeners use a technique called "micro-beveling" — adding 1–2° on the final fine-grit hone for extra durability without sacrificing much sharpness. For beginners, consistency at one angle throughout the progression (coarse → medium → fine → strop) is far more important than micro-beveling. Focus on holding steady first.

This tool uses your device's built-in accelerometer and gyroscope (via the DeviceOrientation API) to detect the tilt angle of your phone in real time. When enabled, place your phone on the same surface as your sharpening stone, then tilt it to match your desired angle. The canvas visualization updates live, and the angle display changes color — green when within ±1° of target, amber within ±3°, and red when off. Use the Calibrate Zero button to set a reference point if your work surface isn't perfectly level. Note: iOS 13+ requires a one-time permission grant via the enable button.

It depends on usage, but here are general guidelines:
• Home kitchen knives: Hone with a steel weekly, full sharpen every 2–4 months.
• Professional chef knives: Hone daily, sharpen every 2–4 weeks.
• Pocket / EDC knives: Touch up every 1–3 months depending on use.
• Outdoor / hunting knives: Sharpen before and after each major trip.
A dull knife is actually more dangerous than a sharp one because it requires more force and is more likely to slip. The paper test — if your knife can't cleanly slice through a sheet of printer paper — it's time.

Sharpening (on a whetstone or diamond plate) removes metal to create a new edge — do this when the blade is truly dull. Honing (with a steel or ceramic rod) realigns the microscopic edge that bends over during use without removing significant metal — do this frequently between sharpenings. Think of sharpening as re-forming the edge, and honing as re-straightening it. Both are essential for maintaining peak knife performance.