Grinding Wheel Safety

Demonstration by Jock Dempsey

September 27, 2000

Tonights demo is going to be a short one on Grinding Wheel Safety. Bench grinders are something we use every day and few think about maintaining them for safety.

Grinding wheel safety starts with checking the wheel for cracks by “ringing” the wheel. Inspect it visualy then balance it on a finger in the mounting mounting hole and give it a sideways tap with a screwdriver or small hammer handle. It should make a low but clear ring. If not it may be cracked.

You also want to be sure the wheel is rated for the speed of your machine and is a proper fit. Always use the proper mounting or “safety flanges” that came with your grinder. The inside flange should be keyed or driven by the shaft.

All new grinding wheels come with soft paper washers. These provide the friction to drive the wheel and privide a soft cushion for the flanges.

DO NOT mount wheels that have damaged or missing washers.

After mounting the wheel it is recommended to let it run for a full minute before use.

On most modern grinders there is an adjustable “shatter guard”. Thats the adjustable flat bar at the top of the guard opening. This needs to be adjusted to have as little clearance as possible. Ususaly 1/16″ (2mm). The tool rest should also be adjusted about the same

The shatter guard stops a broken wheel before the broken section can reach the opening in the guard. As the wheel wears it should be kept adjusted. The closer it is, the sooner a broken wheel stops and the safer your grinder.

 With new wheels you should adjust the gards, dress the wheel, then readjust.

guru, the cheap grinders I have lack the shatter guard. . think I’ll fake some.

Rough wheels can be dressed with a “star wheel” dresser. Wheels for grinding drills and cutter bits should be dressed with a diamond dresser.

Mounted industrial diamonds for dressing wheels are relatively inexpensive ($30 – $50 US) and last almost forever

OSHA Requires the shatter guards and you should too.

ONE VERY IMPORTANT LITTLE KNOWN RULE:

Never grind anything that is close to or greater than the weight of the wheel!

 Small work bounces off the wheel. Work heavier than the wheel bounces the wheel and has a high likelyhood of breaking the wheel.

Questions? Comments?

 Jock, perhaps a comment on grinding rest clearance

The tool rest should be adjusted similar to the “shatter guard” to prevent work getting caught between the wheel and the tool rest.

The biggest problem I have with bench grinders is people using them to clean up torched plate and that type of rough work.

They make grinders for that class of work but they are HUGE. Typical bench and pedestal grinders are designed for tool grinding. Drills, cutter bits, chisles.

Heavier and rough work should be ground with an angle grinder.