• LIKELY QUESTIONS •

Answers to Commonly Asked Questions About Diamond Tools

1.How do we sort and classify loose stones?

Loose stones are first sorted by geometric shape (Crystals, Macles, Elongated, etc.).
These are further broken down into size and quality (Number and degree of imperfections).

2.Does the color of a stone have any bearing on its hardness or abrasive quality ? if so, What

In general, the color of  the diamond does not have any effect on the hardness or abrasive quality of the stone. There is one minor exception:  Some brown diamonds tend to be less vulnerable to chipping in certain application. This does not amount  to much in practice, since all diamonds are brittle and will chip easily mishandled.

3.Why are reset stones generally darker, less lustrous in appearance?

Generally after a diamond has been used, a certain amount of detrimental heat and pressure result in
some cracks and graphitization of the diamond, this is also true to a very minor degree in the procedure used to set the diamond in the matrix.

4.Does a diamond's surface smoothness influence tool performance?

Surface smoothness will have no detrimental effect on the performance of an unlapped dressing tool.
It will have a definite bearing a definite bearing on the overall performance of lapped tools
(boring, turning, diaforms, hoggluds, etc.)

5.What criteria are used to select the best point of a diamond?

The  Point of each diamond is selected for its degree of sharpness, structural strength and lack of
detrimental flaws. One must realize that a diamond is not isotropic like glass. Diamond has a grain
structure and is therefore very resistant to abrasion along a certain axis.  We as a diamond tool 
manufacturer, try to mount each diamond so that in the dressing action the grinding wheel runs against these axes.

6.Does coning weaken a stone? Is there such a thing as skin hardness?

It is generally accepted that coning does weaken a stone somewhat due to the removal of the sharp axis along its edges. This weakening may be further explained by removal of material mass to create the necessary included angle in a coned point dresser. Yes, this skin has a definite bearing on tool use, particularly on the coated octahedron or Congo Diamond, this skin is apparent to the naked eye on this the of diamond and is actually a coating of diamond of different makeup than the original stone. It is normally not as fully crystallized or as hard as the central crystal due to its later geological forming.

 
7.What is the significance of point included angles.
Point included angles will vary depending on the form or profile to be dressed in the wheel. It is generally accepted that in clued angles on the diamond should never be less than 60⁰ degrees on a coned type diamond or less than 40⁰ degrees on a lapped tool.  It is General rule of thumb to use as wide an included angle as the profile will permit.

8.What are realistic acceptable natural radius specifications for single Points?
   Will the grain size of my grinding wheel have any effect on these points?

Practical radius specifications vary greatly depending upon the application.

These may range from .002 -.005 on thread and gear grinding to .020 -.030 on large center less
or external grinders. Unfortunately, there is no generally accepted for mula to define the exact radius
needed for a particular application.
Yes, wheel grain size will have a bearing on natural radius needed and the impact of shock created
by large grained wheels, it is a general rule that the larger the grain, the larger the radius needed and vice versa.

9.Do all diamond forms (Crystals, Octahedrons, etc.) have the same hardness?
Yes, all pure diamonds have the same testing hardness but in practical use not the same abrasion  
resistance.  A particular type of diamond may outperform another in a particular application because
of it particular grain structure. Abrasion resistance is attributed t the great energy required to break the atoms always from their tetrahedral arrangement. If the improper type or shape diamond is used,
it may offer its soft axis to the grinding wheel thus decreasing its potential life.

 
10.How do we determine the size of diamond needed for a particular application?
do you know of any formula that can be applied to derive the proper diamond  size to be used.
Most manufacturers base their recommendations individual or past experiences rather than a formula. There are several mathematical formula available, however we have found that the application of such formulas result in the use of a larger-than-necessary stone

11.What are the practical wear limits for single points tools?
That is, how much or how large a wear flat generated is tolerable?

A single point diamond should never be overused.  It is generally accepted that once the wear land of the dressing face exceeds .040 in diameter, its efficiency and effectiveness are greatly reduced.
Proper indexing or resetting are then needed to avoid damage to the diamond or its bonding matrix.

12.What temperatures can diamonds withstand? when does graphitization begin and
what is the effect on stone performance?

At approximately 100⁰ F.(870⁰C) in an ordinary atmosphere, a diamond begins to graphite.
In a neutral or oxygen free atmosphere, it will with stand temperatures as high as 2900⁰ F (1590⁰C).
In actual use, this is a contact surface phenomenon. It is detrimental in the dressing cycle when
extreme heat and pressure are created by too great an in feed, Cross feed or lack of the proper coolant flow. When this occurs, graphitization begins and the diamond's abrasion resistance is eliminated.

13.Is there any difference in the processes used to reset diamonds as opposed
to that used in the manufacturing of new tools?

The processes used for new tools and resets are identical. The only significant difference is that a reset stone has to be removed from its original matrix, and re-oriented to its next best point.