Optional Tooling
7-1
HP6A Manual
Chapter 7
Precision Hone Head:
General Operation:
Important - Read this and study carefully before operating the precision head to implement the full
capability of the precision head.
The precision head provides a very stiff back-up of the abrasives. This in turn provides rapid bore
correction with very little material removal. The four cutting stones provide more abrasive area and
cutting capability than two-stone heads and should perform 10 to 25% faster with less abrasive cost. You
must, however, have the proper combination of cutting fluid, abrasive bond hardness, stone grit, hone
pressure and feed rate. As with all machines, patience is necessary initially so that you organize and
become familiar with the mesh of these variables. Blending them and proper adaptation to switching
holders for the size changing will increase your productivity.
Care must be exercised in starting honing operations in a tapered hole since the stiffness of the abrasives
can easily lock the hone head in tight bore. If the hone is started in the large end of a tapered hole the
hone head could bind by the time it reaches the small end of the tapered hole.
Carefully study how to switch holders for size ranges. Once you have adequate abrasives loaded in the
holders and you keep them stored properly in the file, size changes can be made in a minute. If it is
necessary to change sleeves to a new range, that will take a minute more.
The precision hone head expands .0003” (.008 mm) with every wheel graduation or up-feed. Ten feed-
ups will remove .003” (.08 mm) of stock, less abrasive wear, if the load meter remains constant.
Automotive bores often require a good deal of attention at the bottom of cylinders which allow limited
lower over-stroke. Use the part 514-8-27, stone depth scale assembly, to maximize over-strokes. Use 3”
abrasives and make sure the lower stop is set as low as possible without interfering with lower bore
obstructions. The finish load percentage has a large affect on lower bore and thin wall cylinder geometry.
Generally lowering the finish load percentage will increase the accuracy of the lower bore area.
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