Orbital Mechanism And Blade; Blade Movement; Orbital Position Selection - Hitachi CJ 90VST Technical And Service Manual

ORBITAL MECHANISM AND BLADE

1. Blade Movement

In the Model CJ 90VST, the orbital mechanism moves the blade up and down, and back and forward. The
amount of fore-and-aft blade movement can be adjusted by simply switching the change knob to any of the
four settings. The table below shows the modeled orbits of blade movement at each orbital position
(change knob position).
III
III
2.0 mm (5/64")

2. Orbital Position Selection

Selecting the most appropriate orbital position for each cutting job is essential to achieve the best possible
cutting efficiency. However, as the best orbital position depends on workpiece hardness and thickness, the
desired finish of the cut surface, and other factors, setting a single, simple standard for selecting the best
orbital position is not practical. Table 1 below can be used as a general guide for the appropriate selection
of orbital position based on various factors.
Table 1 General guide for appropriate selection of orbital position
Factor
Material hardness
Material thickness
Cutting speed
Straight cutting or
curved cutting
Surface finish
Material stability
* Set the orbital position to "0" independently of the cutting speed when cutting a small arc or curved line by
using a guide (sold separately).
II
1.2 mm
(3/64")
Soft material
Thick
Faster cutting
Straight cutting
Rough finish acceptable
(splintering, chipping acceptable)
Unstable
II
I
0.6 mm (1/32")
Orbital position
III II
-6-
I
0
Perpendicular
movement only
I 0
Hard material
Thin
Slower cutting
Curved cutting
Fine finish
Very stable
0