The noise levels of bench and pedestal grinders vary with the type of work being performed on the tool. Larger pieces of metal such as 50 mm angle iron will produce much more noise (typically 105 dB(A)) than touching up a drill bit (typically 84 dB(A)). The grade and diameter of the grindstone will also influence the noise level. Because noise levels produced at a grinder can exceed 85 dB(A), personal hearing protection is normally used.
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- Check that the bench grinder is firmly bolted to the bench and parts such as covers and tool rests are not vibrating.
- Replace grindstones that are out of balance, or worn out of round.
- In the case of pedestal grinders bolted to wooden floors either mount the grinder on a concrete plinth or fit anti-vibration rubber mounts to the base of the pedestal.
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- Dampen vibrations: Cement with contact adhesive 6 mm of insertion rubber to the top of the existing tool rest. On top of this, cement a new tool rest of metal plate or other durable material. This can give a noise reduction of up to 7 dB(A) when grinding large material, which is supported on the tool rest.
- Construct a partial enclosure: This enclosure should cover the machine as much as practicable. The construction should be 12 mm chipboard faced internally with 50 mm semi-rigid fibreglass faced with perforated foil.
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- Avoid forcing the work into the grind stone, let the stone work at its own pace. This will increase the life of the grind stone and help in reducing noise levels.
- Hold the work firmly against the tool rest to avoid chattering of the work against the grindstone.
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- Horizontal tool grinders are the most accurate way to grind chisel and plane blades. They are also quieter.
- Investigate the use of a different grit grindstone. Stones of a fine grit produce less noise.
- Cut the work more accurately to minimise grinder use.
- Small work can often be touched up using a sharp file.
Adapted from the Noise Control Manual for Schools with the permission of the Education Department of Western Australia.
