Adjusting the tool rest on a bench grinder is crucial for both safety and achieving precise grinding or sharpening results. The process primarily involves setting the correct angle for your grinding tasks and ensuring a safe gap between the tool rest and the grinding wheel.
How to Adjust the Tool Rest on a Bench Grinder?
Adjusting the tool rest on a bench grinder involves two primary settings: the angle and the gap, both of which are critical for safe and effective operation.
Understanding Tool Rest Adjustments
The tool rest provides a stable platform for supporting workpieces against the grinding wheel. Proper adjustment ensures stability, prevents kickback, and allows for consistent bevel angles when sharpening tools. Incorrect adjustments can lead to dangerous situations, such as the workpiece jamming between the rest and the wheel, or inaccurate sharpening.
Key Adjustments: Angle and Gap
To effectively use your bench grinder, you'll need to master both the angle and the gap adjustments.
Adjusting the Angle for Sharpening Precision
Setting the correct angle is vital for achieving specific bevels on tools like chisels, drill bits, or knife blades. This ensures consistent sharpness and tool performance.
- Loosen the Tool Rest Mechanism: Most bench grinders have a knob or lever beneath the tool rest that, when loosened, allows the rest to pivot and change its angle.
- Position Your Angle Gauge: As per the guidelines for setting the angle of your tool rest, you need to place the angle gauge flat on the table of your tool rest with the selected bevel angle face down, and extending towards the wheel face. This ensures the angle gauge is correctly aligned with the intended grinding surface.
- Set the Desired Angle: Carefully adjust the tool rest until its surface aligns perfectly with the desired angle on your angle gauge. Common sharpening angles vary depending on the tool.
- Secure the Tool Rest: Once the angle is set, firmly tighten the knob or lever to lock the tool rest in place. Double-check that it is stable and won't shift during operation.
Here's a table of common sharpening angles for various tools:
| Tool Type | Recommended Sharpening Angle |
|---|---|
| Chisels | 25°–30° |
| Drill Bits | 118°–135° |
| Lathe Tools | 15°–30° (depending on tool) |
| Axes/Hatchets | 25°–35° |
| Knives (General Use) | 20°–25° |
Setting the Optimal Gap for Safety
The gap between the tool rest and the grinding wheel is a critical safety measure. A proper gap prevents small workpieces from being pulled down and jammed between the rest and the wheel, which can cause kickback or damage to the wheel.
- Loosen the Securing Bolts/Knobs: Similar to angle adjustment, there are usually bolts or knobs that secure the tool rest to the grinder's housing. Loosen these to allow the tool rest to slide horizontally.
- Adjust the Proximity to the Wheel: Slide the tool rest as close as possible to the grinding wheel without touching it. The generally accepted safe gap is no more than 1/8 inch (3 mm). This minimal gap prevents workpieces from getting caught.
- Test the Gap: Rotate the grinding wheel by hand (with the power off) to ensure there is no contact between the wheel and the tool rest at any point.
- Tighten Securely: Once the gap is set correctly, firmly tighten all securing bolts or knobs. Ensure the tool rest is rigid and won't move during use.
Safety Tips for Tool Rest Adjustment:
- Always disconnect power before making any adjustments to prevent accidental starts.
- Check tightness regularly, especially after prolonged use. Vibrations can cause adjustments to loosen.
- Maintain the 1/8 inch gap to prevent dangerous jamming.
- Inspect the grinding wheel for wear or damage before adjusting and using the tool rest.
By meticulously adjusting both the angle and the gap of your bench grinder's tool rest, you ensure a safe working environment and achieve consistently precise grinding and sharpening results for all your tools.
