Operating Instructions
3-3
HP6A Manual
Limited Over Travel and Blind Holes:
A problem with stock removal with hone heads exists on many of today’s blocks and cylinders. It may be
necessary to relieve bores with a die grinder, portable grinder or boring bar.
Cross Hatch Angle:
Below is a formula used to determine what Strokes Per Minute and RPM to use to get a given cross hatch
angle. This formula is also available in Microsoft Excel format from Rottler Manufacturing via e-mail or
floppy disk. Several factors affect the crosshatch angle, below is a definition of these factors as they are
used in the formula.
RPM = Revolutions Per Minute the hone head is turning
L = Stroke Length. Actual length the hone head is moving up and down.
DIA = Bore Diameter
SPM = Strokes Per Minute of the Rocker Arm
A = Cross Hatch Angle
Mathematical Equation for SPM with given angle: (TAN(A/2))(*DIA*RPM)/(0.6366*L)
You will need a Scientific calculator to figure the TAN (tangent) or use the following table to get the
Tangent for a given angle.
Example:
A = 27 Degrees
DIA = 4.00
RPM = 195
L = 4.00
(TAN(27/2))(*4.00*195)/(0.6366*4.00) – Instead of doing the calculation in the shaded area use the table
to get the Tangent for that Angle as such: (.2400)(*4.00*195)/(0.6366*4.00)
ANGLE TANGENT ANGLE TANGENT
20 .1763 30 .2679
21 .1853 31 .2773
22 .1943 32 .2867
23 .2034 33 .2962
24 .2125 34 .3057
25 .2216 35 .3152
26 .2308 36 .3249
27 .2400 37 .3346
28 .2493 38 .3443
29 .2586 39 .3541
The remaining equation would be as follows:
Step 1, multiply first set: .2400 x 4.00 x 195 = 187.2
Step 2, multiply second set: 0.6366 x 4.00 = 2.5464
Step 3, divide Step 1 by Step 2 187.2 / 2.5464 = 73.5 or 74 Strokes Per Minute
Honing In General
The HP6A is capable of honing a cylinder very accurately with very little or no work from the operator.
The goal of the operator should be to set the Upper and Lower Stops correctly, select the proper stone
length, and honing pressure that will allow the machine to hone the cylinder to size.
While the HP6A is running, pay attention to the load display (upper left on the control panel). The load
display measures the actual motor load and displays it in percentage of rated motor current. As the
HP6A is honing, the control takes current measurements from the motor throughout the length of the
cylinder and displays them with the lights. The farther the lights move to the right the smaller the bore is
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