Chapter 13 Offhand Grinding

Objectives Identify the various types of offhand grinders. Dress and true a grinding wheel. Prepare a grinder for safe operation. Baldor

Objectives Use an offhand grinder safely. Describe the use of wet and dry grinders. Goodheart-Willcox Publisher

Grinding Tasks Sharpening tools Removing material too hard to be machined by other techniques Cleaning parting lines from castings and forgings Finishing and polishing molds

How Grinding Machines Work Goodheart-Willcox Publisher

Offhand Grinding Use of bench, pedestal, or belt grinder Work does not require great accuracy Part held in hands and manipulated until ground to desired shape

Bench Grinder Fitted to a bench or table Grinding wheels mount directly on motor shaft Coarse Fine Baldor

Pedestal Grinder Larger than bench grinder Pedestal (base) fastened to floor Wet or dry Tool rest supports work Baldor

Safety Note Wear safety glasses Be sure grinder’s eye shield is in place Do not make tool rest adjustments while the grinding wheels are revolving

Tool Rest Position Goodheart-Willcox Publisher

Abrasive Belt Grinders Heavy-duty version of woodworking belt and disc sanders Variety of abrasive belts Grind to a line Finishing cast and forged parts Deburring Contouring Sharpening American Foundrymen’s Society

Portable Hand Grinders Flexible shaft grinders Precision microgrinders NSK America

Grinding Wheels Coarse abrasive grains bonded into circular shapes Dulled abrasive particles wear away Reveal new, sharp particles Examine frequently for concentricity, roundness, and cracks Praethip Docekalova/Shutterstock.com

Ring Test Goodheart-Willcox Publisher

Wheel Dresser Trues wheel Provides better grinding surface Goodheart-Willcox Publisher

Loading and Glazing Loading Glazing Occurs when grinding soft metals Small pieces of material clog wheel Glazing Occurs when grinding very hard metal Grains dull before they can fall away Both cause wheel to cut inefficiently

Grinding Rules Grind using face of wheel Move work back and forth across face Keep wheel dressed and tool rests properly adjusted Grind soft metals on abrasive belt grinder when possible

Abrasive Belt and Wheel Grinder Safety Make sure tool rest is properly adjusted Wear goggles or face shield when grinding Never operate while senses are impaired Check machine thoroughly before using Check wheel for soundness before putting on grinder Do not use glazed or loaded wheel

Abrasive Belt and Wheel Grinder Safety Be sure wheel guards and safety devices are in place Hook up exhaust attachments if needed Do not stand directly in front of wheel Hold small work in clamp or hand vise Avoid work pressure on the side of wheel Keep hands clear of rotating wheel

Abrasive Belt and Wheel Grinder Safety Never operate at speeds higher than recommended Have injuries treated immediately Allow wheels or belt to stop completely before making adjustments

Being an Efficient Employee Workplace Skills Being an Efficient Employee Efficiency can always be improved Examine methods you use Are newer, better methods now possible? Tips Set priorities each day Match tasks to energy levels Organize the work environment

Using a Dry Grinder Place work on tool rest and slowly push against grinding wheel Avoid using too much pressure Minimize overheating to avoid removing temper Goodheart-Willcox Publisher

Using a Wet Grinder Use slightly crowned face when grinding carbide-tipped tools Use ample coolant at all times Use entire face of wheel Goodheart-Willcox Publisher

Adjusting the Clearance Angle Goodheart-Willcox Publisher