Grinding wheels, like other cutting tools, require frequent reconditioning of cutting surfaces to perform efficiently.  Dressing is the term used to describe the process of cleaning the periphery of grinding wheels.  This cleaning breaks away dull abrasive grains and smoothes the surface so that there are no grooves.  Truing is the term used to describe the removal of material from the cutting face of the wheel so that the resultant surface runs absolutely true to some other surface such as the grinding wheel shaft. If grinding wheels get out of balance because of out of roundness, dressing the wheel will usually remedy the condition.  A grinding wheel can get out balance by being left with part of the wheel immersed in the coolant; if this happens, the wheel should be removed and dried out by baking.  If the wheel gets out of balance axially, it probably will not affect the efficiency of the wheel on bench and pedestal grinders.  This unbalance may be remedied simply by removing the wheel and cleaning the shaft spindle and spindle hole in the wheel and the flanges.
