When dressing with either diamond single points, grit (mesh), PCD (Poly Crystalline), and/or hand set or random stone tools, the infeed MUST BE .001 MAXIMUM. Why? Because the diamond dressing tool will crush the vitrified bond. A .002 infeed can crack the bond as deep as .009 into the wheel causing the cracked, crushed bond to begin to break apart. As the wheel grinds, larger gullet areas form. The larger gullets catch the chips and create loading. As this loading continues the wheel becomes hot. This causes chatter, leading to bounce. Poor finish and burn are the results. Usually, the dressing is repeated and the cycle continues.
If large amounts of abrasive have to be removed, take a heavier roughing dress, but finish with 9 to 16 passes at .001 maximum, in order to get a solid wheel.
Because of age, many grinding machines have worn, hard to read scales on their hand wheels, backlash, and/or worn dressing equipment. Setting up a dial indicator will inform you of the infeed travel measurement. Also consider a Sony digital readout for multiple benefits.
When dressing with a single point diamond tool for straight dressing, use a pointed crystal octahedron. For fine abrasive wheels, use sharp crystal points. Gothic shaped crystal octahedrons are for 46 and 60 grit wheels. The point is kept sharp by turning the tool 6 to 12 indexes per one revolution. Index as necessary. The top 25% of an octahedron diamond has the hard grain running to the point which is the hard direction section. The remaining 75% are the other pyramid corners. So... don't grind into the shank. When the wheel gets close to the shank, send the dressing tool in for resetting.
Why dress with a sharp point? For normal dressing the sharp point will "thread" the surface of the wheel as well as make the wheel round and straight. When mounting and dressing a new wheel, the sides should be dressed straight and true. This application requires very sharp crystal diamond points. A dull, rounded over diamond can crush or push away the wheel, resulting in a tapered surface.
Use octahedron shaped diamonds. This shape has eight sides and the crystal structure has the hard grain running to the point. The top 25% of the pyramids have the best hard usable area. Reset when almost worn down to the shank.
When grinding wet, dress wet.
When grinding dry, dress dry.
This will insure that the coolant will not splash onto a hot diamond and shatter it! Happy Grinding!
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