Grinding Lathe Cutting Tools Unit 50

Objectives Explain importance of various rakes and clearance cutting-tool angles Grind general-purpose cutting tool from blank Resharpen dull cutting tool

Grinding Lathe Cutting Tool Wide variety of cutting tools for lathe All have certain angles and clearances regardless of shape Shape and Dimensions of General-purpose Lathe Toolbit Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

To Grind a General-Purpose Toolbit Dress face of grinding wheel Grip toolbit firmly, supporting hands on grinder toolrest Hold toolbit at proper angel to grind cutting edge angle Tilt bottom of toolbit toward wheel and grind 10º side relief or clearance angle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Cutting edge ~ ½ In long and extend over ¼ width of toolbit 10º side relief or clearance angle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

While grinding, move toolbit back and forth across face of wheel Prevents grooving wheel Toolbit must be cooled frequently during grinding Never overheat toolbit! Never quench stellite or cemented-carbide tools Never grind carbides with aluminum oxide wheel

Grind end cutting edge so it forms angle of a little less than 90º with side cutting edge Hold tool so that end cutting edge angle and end relief angle of 15º ground at same time 70º to 80º Point Angle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Using toolbit grinding gage, check amount of end relief when toolbit is in toolholder Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Side rake ground the length of the cutting edge Hold top of toolbit approximately 45º to axis of wheel and grind side rake to approximately 14º Do not grind below top of toolbit Creates a chip trap Side rake ground the length of the cutting edge Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

With oilstone, hone cutting edge of toolbit slightly Grind slight radius on point of cutting tool, being sure to maintain same front and side clearance angle With oilstone, hone cutting edge of toolbit slightly Lengthen life of toolbit Enable it to produce better surface finish on workpiece