The Lindsay Air Chasing Graver has several impact
adjustments allowing users to vary the impact characteristics. The tools porting may be
adjusted to vary the piston's length of stroke and impact frequency. The piston's length
of stroke can be adjusted anywhere between 3/8 of an inch or just a few thousands of an
inch.
Once the porting is adjusted by the user, the length of stroke varies only slightly
throughout air pressure ranges, although piston speed and velocity increase as pressure
increases. When the length of stroke is shortened using the porting adjustment, the impact
frequency increases. When set to an extremely short stroke, the impacts can increase to
12,600 per minute @ 25 PSI, or to 24,500 @ 50 PSI. Because the stroke adjustment can be
made so short (.010" or less in length) the piston gains little velocity resulting in
fast, delicate impacts which give the tool very smooth cutting control. This short stroke
setting works well for fine line banknote style of engraving. When the foot control is
depressed, the tool begins impacting and increasing in speed, but upon release the
handpiece idle always returns to approximately 2,520. Impacts can range from 2,520
to 24,500 per minute, depending on the air pressure and porting set by the user. This
porting adjustment is unique to the Lindsay Air Chasing Graver and, together with its
small size, gives the jeweler and engraver a great advantage.
(Above) Maximum engraving depths. Dime included in photo for
size comparison. Chips from the last two deep cuts are also shown.
Pressure:
Width of cut: |
1 psi
.005" |
5 psi
.012" |
10 psi
.017" |
15 psi
.021" |
20 psi
.032" |
25 psi
.040" |
30 psi
.050" |
35 psi
.052" |
40 psi
.055" |
45 psi
.061" |
50 psi
.063" (1/16") |
The Lindsay Air Chasing Graver excels at adjustments for extremely fine microscope engraving. To
demonstrate the other end of the scale, the above mild steel plate was engraved with a
serious of cuts to show the maximum power of the Air Chasing Graver. The handpiece porting
adjustment was set to the longest stroke. A 3/32" slightly opened up square carbide
graver was sharpened with a 45 degree face and 17 degree heel. The air regulator was first
set to approximately 1 PSI, the graver was positioned at the start of the cut, and the
foot control valve was fully depressed so that the handpiece would receive maximum air
pressure. The graver cuts were kept as deep as possible without stalling the cut. The
table above shows the results for each cut, with the PSI setting, and the width in inches.
In general the Air Chasing Graver has the power for extremely fine to medium depth
engraving. If more power is required, the Omega AirGraver
may be a better choice of tools.
Air Chasing Graver