TECHANGLE November 30, 2005
FREQUENTLY ASKED QUESTIONS
WHAT IS A TECHANGLE WRENCH?
The
TECHANGLE™ wrench is an electronic torque and angle wrench. It is designed to provide
basic electronic features, including UNITS CONVERSION, (Nm, ft-lb and in-lb) TRACK, PEAK
HOLD, and PRESET functions on a robust, yet ergonomically comfortable, wrench platform. The
ANGLE mode utilizes piezo gyroscope technology that requires no mechanical reference. It is
priced to compete with mechanical bending beam, dial, preset and adjustable click-type torque
wrenches, and angle gauges.
HOW DOES IT WORK?
The TECHANGLE wrench emulates a mechanical dial or “click” type wrench or reference-free
angle gauge for “turn-of-the-nut” type applications. The display shows the torque or angle
specification, (PRESET values) that can be changed immediately using the UP and DOWN
pushbuttons. The torque units or angular degrees units of measure are selected by using the
UNITS conversion pushbutton.
In torque mode, when load is applied the display automatically switches to TRACK mode,
emulating a mechanical dial wrench, so the user can monitor torque or angle in real time. Similar
to a click type wrench, at 2% below the preset value, the wrench beeps once and the handle
vibrates, alerting the user to stop increasing torque. When load is released the display
automatically shows the PEAK torque applied for 10 seconds, flashing on and off, thus emulating
a dial wrench with a follow-up pointer.
In angle mode, when load is first sensed, the wrench switches to TRACK mode and accumulates
fastener rotation in angular degrees. Reverse motion is ignored to allow ratcheting action in tight
work places. When load is released the display automatically shows the PEAK angle and torque
applied, alternating, for 10 seconds. This is also useful for keeping an eye on torque applied
while in the angle measurement mode. Angle will continue to totalize if load is reapplied before
the 10-second period has elapsed. If PRESET alert has occurred or the 10-second PEAK display
has elapsed or the ON/RESET key is pressed, the wrench is ready to move to the next fastener
and start accumulating from zero again.
Note: when entering the angle measurement mode the wrench must be momentarily held still to
establish a zero angle reference in space. The display shows two small bars “- -“ alternating if
motion is detected during zero reset.
The wrench turns itself off after sitting idle for two minutes to conserve battery power. The
wrench returns to the last PRESET and UNITS settings at power on.
WHY DOES THE TORQUE ALERT SIGNAL 2% EARLY?
A mechanical click wrench releases torque slightly when its PRESET value is reached. This
helps the user to stop applying torque without over-loading the fastener. With the TECHANGLE
wrench, the user must ergonomically respond to the beep and handle vibration. Empirical studies
showed that the typical user overshoots the PRESET value by about 2%. So, the program
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purposely signals torque PRESET alert 2% early to compensate. Refer also to “HOW DOES IT
WORK?” above. Note: angle PRESET alert does not signal early.
WHAT IS THE ACCURACY OF THE TECHANGLE WRENCH?
Complying with the ASME and ISO Standards, the TECHANGLE wrench is accurate to within +/2% in the CW direction and +/-3% in CCW direction from 20% to 100% of full scale. Refer to the
specifications page for more details.
Angle accuracy is within 1% of reading +/-1 degree.
WHAT AFFECTS ACCURACY?
Handhold position: To provide a robust, yet cost effective design, the TECHANGLE wrench
uses strain-gaged, bending beam, torque sensing technology. To get the best accuracy, users
must apply load to the center of the handhold position. Moving off the center of the handle can
induce errors as much as:
Although the angle display does compensate for wrench bending, handhold position error of
angle measurements is insignificant.
Flex-head position: Because the flex-head can place the center of the socket drive some
distance away from the center of the calibration length (non-flexed drive axis to handhold
position), compensation for torque setting or display reading may be nece ssary. Using a deepwell socket, for example, can result in errors as much as:
Using the flex-ratchet other than in the straight position can result in angle measurement errors
by the cosine of the flex angle. For example, at full flex (+/-15 Degrees):
Temperature: The TECHANGLE wrench utilizes full-bridge strain gage sensing to provide
excellent temperature compensation. The wrench will maintain accuracy per ASME
STANDARDS at room temperature (23 degrees C) +/-10 degrees C. Electronic display drift is
DISTANCE FROM CENTER OF HANDLE
MODEL RANGE
ATECH2FR100 100 ft-lb
ATECH3FR250 250 ft-lb
+/- FLEX-HEAD ANGLE
MODEL DRIVE
ATECH2FR100 3/8"
ATECH3FR250 1/2"
COS 15 deg = 0.97
angle readings will be low by about 3% at full flex
% DISPLAY ERROR
1" Short 1" Long 2" Long
-2.49 1.93 3.44
-0.90 1.25 1.79
% DISPLAY ERROR
5 deg 10 deg 15 deg
0.35 1.43 3.33
0.39 1.64 1.80
or
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+0.01% per degree C. The piezo gyroscope, used for angle measurement, drift is –0.12 angular
degrees per Degree C.
Orientation: As with all bending beam, and most click style torque wrenches, the TECHANGLE
wrench is sensitive to gravity induced torque error. Torque wrenches are calibrated in the vertical
position (handle down) or horizontal position (drive facing down) orientations. Whe n the wrench
is used in a horizontal position, with the drive parallel to the surface of the earth, setting and
display errors can be off as much as:
Angle measurement is not affected by gravity or magnetic forces.
HOW CAN I CHECK THE ACCURACY OF THE TECHANGLE WRENCH?
Per ASME B107.28 and ISO 6789 Standards, checking the accuracy of a torque wrench requires
the use of a torque tester/calibrator with accuracy at least four times better than that of the
wrench. The TECHANGLE wrench is calibrated in the horizontal position, with the displ ay facing
up. Per the Standards, the wrench must be exercised three times to full scale in the direction of
test and then both the wrench and tester/calibrator must be zeroed. A constant torque is applied,
(TRACK mode on the tester) by loading at the mark on the handle, and with the flex-head straight
(non-flexed). Never try to test the wrench in the PEAK or FIRST PEAK modes because the
dynamic differences between the wrench and the tester will produce inconsistent results. The
Standards suggest checking the wrench at 20%, 60% and 100% of full scale. Wrench readings
should match the tester display within the sum of the uncertainly specifications for each. For
example, a +/-2% wrench tested using a +/-0.5% tester is within specification if the readings
agree within +/-2.5%. A number of torque testers/calibrators are available from Snap-on Tools.
Presently no ASME or ISO Standard for angle measurement exists. However, the TECHANGLE
wrench is calibrated and checked using a N.I.S.T traceable protractor fixture.
CAN I CALIBRATE THE WRENCH MYSELF?
Yes, with the proper calibration equipment. Refer to Calibration Instructions at home page.
HOW OFTEN SHOULD THE WRENCH BE CALIBRATED?
This question relates to the policy of the particular user, which generally reflects the critical nature
of specific fastener installations. Obviously, military, aerospace and nuclear power facilities will
test their wrenches more often than a backyard mechanic. The TECHANGLE wrench was
designed and tested to comply with ASME and ISO torque Standards for cycle life. The
Standards require 5,000 CW and CCW cycles at full-scale without loss of accuracy. To establish
your own policy, as an example, using a 100 ft-lb wrench to install lug nuts to 100 ft-lb, you can
reliably do 250 automobiles before checking calibration, (5,000 lug nuts / 5 lugs / 4 wheels = 250
cars). If you use the wrench at mid-scale, you can expect to get at least 4 times the cycle life. At
any extent, due to environmental affects, even if the wrench is only used occasionally, it is good
practice to have it checked every six months. As with any measurement instrument, should you
drop it, have it checked. Snap-on Repair Centers are outfitted with the latest in torque and angle
testing/calibration equipment.
Model
TECH2FR100
TECH3FR250
Horizontal Orientation Error
CW CCW UNITS
-0.2 0.2 ft-lb
-1.0 1.0 ft-lb
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IS THE TECHANGLE WRENCH ”INTRINSICALLY SAFE” (EXPLOSION PROOF)?
No. The TECHANGLE is not sealed tight against volatile atmospheres that may ignite should a
spark be generated in its electrical circuitry.
CAN THE TECHANGLE WRENCH BE AUTOCLAVED?
No. Sterilization temperatures and humidity of that level will destroy the wrench.
WHAT ARE THE OPERATING TEMPERATURE LIMITATIONS?
The TECHANGLE wrench was tested between zero and 50 degrees Celsius, (3 2 and 125
degrees Fahrenheit). Although the wrench does work at those extremes, the LCD (
Crystal Display) will get sluggish as the temperature drops and the circuitry will drift out of ASME
Standard specifications, which is within 10 degrees C of room temperature (23 degrees C).
.
CAN THE TECHANGLE WRENCH BE USED IN THE RAIN?
The TECHANGLE wrench assembly uses “O” rings and close fit components to minimize dirt and
grime getting inside. For that reason, it is also claimed to be “splash proof.” However, because
the rigid bezel (electronics and display) assembly must be able to float over the bending steel
frame and handle, it is not sealed tight. Therefore, the TECHANGLE wrench must never be
immersed in any liquid or be directly exposed to moisture that may seep into the electronics.
WHAT IS THE BATTERY LIFE FOR THE TECHWRENCH?
The TECHANGLE wrench was tested continuously with a one second handle vibration every 10
seconds. At this rate, with fresh alkaline cells installed, the battery will operate for over 80 hours.
Even with the display off, the circuitry still draws a fraction of a milliamp. Therefore, the battery
should be removed when the wrench is stored for an extended period of time.
DOES BATTERY VOLTAGE AFFECT ACCURACY?
No. The TECHANGLE regulates the 4.5V battery voltage to 3V, thus insuring measurement
precision. Its micro controller constantly monitors battery voltage as reported by the battery
condition flags on the display. Should the battery fall below the regulator dropout voltage, the
display will show “bAtt” and the wrench cannot be used until the battery cells are replaced.
WHAT DOES “Err0” MEAN ON THE DISPLAY?
Every time the wrench is turned on, and whenever the ON/RESET key is pressed, the wrench
reestablishes a ZERO/TARE for torque. “Err0” (Error Zero) means that a TARE signal, greater
than 20% of full scale, is coming from the bending-beam sensor as the wrench is trying to ZERO
itself. Such a signal is indicative of torque being applied during ZERO set, a bad gage, open
gage wiring, or a permanent set taken by an over-loaded sensor. In any case, the wrench cannot
be used and must be repaired.
LIQUID
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IS THE TECHANGLE WRENCH SKYDROL PROOF?
(CHEMICAL RESISTANCE)
No, practically nothing is Skydrol proof! However, the materials chosen for use in the
TECHANGLE wrench have all been proven in existing Snap-on products, such as screwdriver
handles, cordless power tools and diagnostic equipment housings. Casual contact, even with the
most reactive solvents, has little affect on function or finish. Most chemicals evaporate before
doing any damage. The nylon display window will not fog, except due to abrasion. Replacement
of the plastic components, should the tool experience damage due to prolonged chemical
exposure or physical abuse, is relatively inexpensive. The following plastics materials are used in
the TECHANGLE wrench:
Handle and electronics bezel – Nylon, 30% glass filled
End cap, battery tray, trim ring – Polypropylene
Soft grip handle – Santoprene
Display window – Transparent Nylon (Grilamid TR90)
Keypad – Silicone Rubber
Sensor and endcap “O” rings - Buna-N (Nitrile)
Each of these materials was tested by applying chemicals, identified in Snap-on Standard
ES60.12J, that are typical of the automotive repair environment, including:
Denatured Alcohol, #2 Diesel Fuel
30W Motor Oil, Unle aded Gasoline
Transmission Fluid Carburetor Cleaner
Naphtha Brake Fluid (Similar to Skydrol )
Lacquer Thinner Nitro Methane (Racing Fuel)
SIGNIFICANT RESULTS:
The keypad expands in volume up to 100% when soaked for 24 hours in diesel fuel,
naphtha, gasoline and lacquer thinner. However, it returns to normal when the solvents
are removed and have evaporated.
According to published data, the soft grip, Santoprene, will expand 3% when immersed
into brake fluid for one week and will shrink 15% when immersed into gasoline for one
week.
WHAT HAPPENS IF I DROP THE TECHANGLE WRENCH?
All models of the TECHANGLE wrench were drop tested per Government Standard GGG-W686E with the following results:
One sample wrench was dropped six times, [three times beyond the standard] from four
positions horizontally, [three positions beyond the Standard] and once on each end from
a height of three feet onto a concrete floor. No failures were noted.
POST DROP TEST CALIBRATION CHECK:
All wrenches remained functional and within accuracy specifications.
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