Tech Talk
What are the guidelines for truing and dressing with "Single Point Diamonds"?
The Diamond point should be set at an angle of 10 to 15 degrees in the direction of the wheel rotation and also, if possible, by the same amount in the direction of the cross feed traverse during the truing. The dragging effect resulting from this angling, combined with the occasional rotation of the diamond point in its holder, will prolong the diamond life by limiting the extent of wear facets and will also tend to produce a pyramid shape to the Diamond tip. The Diamond should also be set to contact the wheel 1/8" to 1/4" inch below its centerline.
1. The diamond crossfeed rate may be varied to some extent depending on the required wheel surface; faster crossfeed for free cutting, and slower crossfeed for producing fine finishes. Such variations, however, must always stay within the limits set by the grain size of the wheel. Thus the advance rate of the truing diamond per wheel revolution should not exceed the diameter of a grain or be less than half of that rate. Consequently, the diamond crossfeed must be slower for a large wheel than a smaller wheel having the same grain size number.
2. Coolant should be applied before the diamond comes into contact with the wheel and must be continued in generous supply while truing.
3. The speed of the grinding wheel should be at the regular grinding rate, or not much lower.
4. The initial approach of the diamond to the wheel surface must be carried out carefully to prevent sudden contact with the diamond, resulting in penetration in excess of the selected depth of cut. It should be noted that the highest point of a worn wheel is often its center portion and not at the edge from which the crossfeed of the Diamond starts.
5. The general conditions of a truing device are important for the best truing results and for assuring extended diamond life. A rigid truing spindle, well seated diamond nib, and firmly set diamond point are mandatory. Sensitive infeed and smooth traverse movement at uniform speed also must be maintained.
6. Resetting of the diamond point. Never let the diamond point wear to a degree where the grinding wheel is in contact with the steel. Such contact will damage the diamond and the setting of the diamond and result in its loss. Expert resetting of a worn Diamond can repeatedly add to its useful life, even when applied to lighter work because of reduced size.
