4
OPERATION
STROKES PER MINUTE (SPM)
Stroke speed setting is a
matter of personal preference
and experience. Generally
speaking, lower speed
settings are preferred for some
stippling, matting or staking
functions. Try mid range
settings for tasks requiring
maximum power. Higher
speeds work best for fine,
delicate cuts and to obtain the
best finish. The GraverMach
AT shows a range of 400 to
8,000 strokes per minute. The
calibrations on the dial are
only approximate. Each model
of handpiece has a normal
range of strokes per minute.
Operating outside this range
can produce erratic operation.
HOW TO TUNE THE
GRAVERMACH AT
(Fig. 4) By tuning your machine, we mean adjusting the
strokes per minute and air pressure for optimum performance.
TUNING YOUR MACHINE PROPERLY IS THE SINGLE MOST
IMPORTANT OPERATION YOU SHOULD LEARN.
1. Turn ON your air compressor and allow the tank to fill. Wait for
the compressor to cycle off and stop running.
SPECIAL NOTE: When you turn on the GraverMach AT, you hear
a little puff of air coming from the inside. This is an electrically
controlled air solenoid valve designed to come on when the
machine is powered up. It will make a pop and hiss sound when
the unit is turned off. This feature is designed to allow the user to
turn off the air supply at the GraverMach AT when you are leaving
the bench area for a break. It will keep air in your compressor
tank when your machine is not running.
2. Turn on the GraverMach AT and select handpiece port 1
or 2 to operate the handpiece of your choice. Next, move
the hand/foot selector control knob to the operating system
you wish to use. Now, set the stroke per minute dial at 2300
and using the regulator knob (Fig. 4-B) on the front of the
machine, back the air pressure down to 2 to 5 PSI (0.1 to 0.4
bar). Close the bias valve (Fig. 4-C).
3. Hold the handpiece you have selected to use with the tool
holder end up (vertically) next to your ear (Fig. 5).
4. WITHOUT depressing the
foot throttle or hand control,
SLOWLY increase the air
pressure until the handpiece
begins to buzz. While
continuing to increase the
air pressure, the handpiece
will vibrate, more air
pressure will make it knock.
Slowly add air pressure and
when the knocking barely
stops, this is considered
the perfect air pressure
operating range for that
particular handpiece.
Another method of tuning (although not as precise) is to use
the initial setting shown in the chart below. Set the Strokes
Per Minute dial to the Recommended Initial Setting. Set the air
regulator knob to Recommended Initial Setting for the handpiece
you are using. The goal is to use the least air pressure possible
that will properly operate the handpiece. Remember, if the
handpiece vibrates without depressing the foot control, the air
pressure is probably too low. If the handpiece fades out at full
throttle, the air pressure is probably too low, or the strokes per
minute is too high for that handpiece. The handpiece should
start to operate within 3/8" (9.525mm) of depression of the foot
throttle. If it doesn’t, the air pressure is probably too high. Always
make small adjustments in air pressure or strokes per minute,
not large ones, until you are familiar with your machine. If you
have tuned your machine properly, the handpiece will operate
smoothly and predictably. New operators often use too much
Fig. 4 • GraverMach AT Tuning
A. Strokes Per Minute (SPM) dial
B. Air regulator knob
C. Bias control knob
• IMPORTANT: Make sure the bias
control is closed (OFF) before
tuning the machine.
• TO CLOSE: Turn bias knob
clockwise until it stops.
A
B
C
Fig. 5
HANDPIECE TUNING CHART
004-940 Magnum
800 - 3400
20 - 23 psi (1.3 - 1.5 bar)
2400
21 psi (1.4 bar)
Standard Spring
2300 - 4000
11 - 14 psi (0.7 - 0.9 bar)
3600
12 psi (0.8 bar)
Fine Spring
2300 - 4000
5 - 9 psi (.34 - .62 bar)
3600
7 psi (0.4 bar)
Standard Spring
1400 - 3400
18 - 22 psi (1.2 - 1.5 bar)
2700
19 psi (1.3 bar)
Fine Spring
1600 - 3600
12 - 15 psi (0.8 - 1.0 bar)
3000
13 psi (0.9 bar)
004-506 Large
800 - 2400
20 - 30 psi (1.4 - 2.1 bar)
1400
24 psi (1.6 bar)
004-508 Standard
1000 - 2800
18 - 23 psi (1.2 - 1.6 bar)
2000
20 psi (1.4 bar)
004-563 Bulino
1600 - 4000
19 - 23 psi (1.3 - 1.6 bar)
3000
20 psi (1.4 bar)
004-610/609 Hammer
1000 - 2700
20 - 25 psi (1.4 - 1.7 bar)
1800
22 psi (1.5 bar)
004-710 Hammer
1000 - 2700
20 - 25 psi (1.4 - 1.7 bar)
1800
22 psi (1.5 bar)
004-801/810 1800 - 4000
21 - 25 psi (1.5 - 1.7 bar)
3000
22 psi (1.5 bar)
004-720 Heavy-Duty
800 - 2400
20 - 30 psi (1.4 - 2.1 bar)
1400
24 psi (1.6 bar)
Normal
Air Pressure Range
psi (bar)
Normal
Operating Range
Strokes Per Minute
Recommended Initial Setting
Air Pressure
psi (bar)
Handpiece Type
Strokes
Per Minute
004-901/910
004-921/926
Monarch
