We have a small bench grinder kindly donated by a member (Hilka 6" 0.5HP/370W 3000rpm p/n 91 6000 12). It is a moderately dangerous tool so training is required before members are permitted to use it. Please only use it for grinding steel. It is useful for sharpening a range of tools or smoothing steel parts. A common use is for making custom shaped cutting tools for the lathes we have. Also, if the end breaks off a drill it can often be made good again by regrinding the jagged tip. It is more versatile than a hand file for doing certain shaping operations on hard metals.
Using the grinder
Make sure that the grinding wheels are in good condition without cracks or chips before turning on the motor. If you see any damage report it to an owner and put a large label on the tool warning people not to use it. Exploding wheels can cause a lot of damage even though they are partially encased.
Hold the workpiece on the work rest whenever possible. If a particular angle is needed then hold the workpiece high enough above the work rest to remove any danger of it banging any supports or guards. Point the workpiece down so that it cannot dig into the wheel and potentially trap your fingers against the rest. Only use light pressure when grinding. The workpiece can heat up very quickly and hardened steel can easily loose its temper. If you need to remove a lot of metal then cool the workpiece in water very frequently (as often as every two seconds). Grinding soft metals like aluminium clogs up the wheel and stops it grinding. Operators can be tempted to use more force to continue grinding but all this does is heat up the wheel. In extreme circumstances this can make it explode and cause injury.
Health and Safety
Check the wheels to ensure they are in good condition before each use.
The operator and anyone nearby should wear goggles as protection against the sparks.
Do not wear gloves. The workpiece should not be allowed to get hot enough to cause burns.
Only the owners should change wheels.
The risk assessment is at Risk assessment.
A very detailed document about abrasive wheel safety can be found at http://www.hse.gov.uk/pubns/books/hsg17.htm
To get trained on the grinder contact one of the owners.
Sessions are advertised on http://meetup.makespace.org
More about the training can be found at
The video below gives a good description of sharping a drill. https://www.youtube.com/watch?v=y0SQkzScQk0