Using a bench grinder

Part 1. Preparation and safety

Objective

• Set up, adjust and use a bench grinder.

Personal safety

Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:

• Work clothing - such as coveralls and steel-capped footwear
• Eye protection - such as safety glasses and face masks
• Ear protection - such as earmuffs and earplugs
• Hand protection - such as rubber gloves and barrier cream
• Respiratory equipment - such as face masks and valved respirators

If you are not certain what is appropriate or required, ask your supervisor.

Safety check

• Stand to the side of the grinder when starting the electric motor.
• Always wear full-face protection, ear protection, leather gloves and a leather apron.
• Use the safety shield fitted to the grinder. If it has been damaged, replace it.
• Do not grind on the side of the wheel because it may cause the wheel to shatter.
• Make sure you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are not sure of what these are, ask your supervisor.

Points to note

• The bench grinder turns an abrasive wheel or wire brush wheel at high speed. These wheels are used to remove metal from a work piece, sharpen tools and clean parts.
• The type of wheel you use will depend on the type and the hardness of the material.
• Whether you are grinding or polishing, use the correct wheel for the material you are grinding or buffing.
• Ask your supervisor to demonstrate the differences between grinding wheels for soft and hard materials and wire brush wheels.
• As the abrasive wheel wears down, the gap between the wheel and the tool rest will increase.
• Make sure the tool rest is as close as possible to the grinding wheel, but not touching it. It needs about a 1/16th of an inch (1.5 mm) gap.
• The face of the abrasive wheel must be kept square. This is done with a dressing tool, which removes some of the abrasive compound.
• If the abrasive wheel is not square, ask your supervisor to demonstrate the use of the dressing tool.
• When grinding metal, it must not overheat. This will affect its hardness. If the metal becomes too hot and is allowed to cool slowly, it may become soft. If it is cooled quickly (quenched), it may become brittle.
• As you shape the metal, dip it into the water pot attached to the bottom of the grinder. This will prevent the metal from getting too hot.
• Some bench grinders are not supplied with a water pot. If this is the case, you will need to have a water pot located near the grinder so that you can cool the piece you are grinding.

Component identification

• Some parts of this illustration are labeled. It is important to learn the names of these equipment components.

Part 2: Step-by-step instruction

1. Set up the bench grinder
   Before you start using the bench grinder, it’s vital that you set it up correctly. When operating, the abrasive wheel turns at high speed and produces dangerous and hot flying particles and sparks. Make sure the grinder is both switched off and disconnected from the power supply before you attempt to adjust it.
2. Use the correct safety equipment
   Certain safety attachments MUST be in place before operating the grinder. They are the wheel guard, the see-through safety shield, the tool rest, a water pot and a full-face protector.
3. Use the correct wheel
   The grinder may have abrasive grinding wheels for removing metal, a wire wheel to clean parts, or both. Make sure the wheel you’re using is appropriate for the job.
4. Adjust the tool rest
   With the correct wheel fitted to the grinder, adjust the tool rest. Position it so there’s at least 1/16th of an inch gap between the wheel, and the tool rest and that it is the same height as the center of the wheel. To adjust the tool rest, locate the adjusting bolt and loosen it with a box wrench. Set the tool rest at the right height and distance from the wheel and then tighten the adjusting bolt. If you are unsure of how to do this, ask your supervisor.
5. Safely use the grinder
   Connect the grinder to the power supply. Adjust your face protector, stand to the side of the wheel and switch the grinder on. Once the grinder is up to speed, move to the front of the wheel, hold the part firmly onto the tool rest, and move it slowly and gently forward until it comes into contact with the wheel. The grinding wheel removes the metal it contacts. Occasionally dip the part into the water to keep it cool.
6. Shut down
   When you have finished, turn off the power and unplug the grinder.