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Dial faces of the TD24 and TD75 Torque Drivers. The black needle indicates the current torque, while the silver memory needle can be used to indicate the desired torque value.

Features

• 0 - 1.5 lb-in and 0 - 75 lb-in Versions Available
• Accurate to 2% of the Reading
• Metal Precision Dial with Dual Units
• Memory Needle
• Not Affected by Hand-Hold Position
• Compatible Imperial and Metric Hex Drivers and SM-Series Spanner Bits Sold Separately Below

The TD24 and TD75 torque drivers are equipped with a precision metal combination dial, and have a 1/4" square drive socket at the end of the handle. A 1/4"-square-to-1/4"-hex adapter is also included with the TD24 driver for compatibility with the SM-series spanner bits available below. The TD24 can provide 0 to 1.5 lb-in of torque, while the TD75 can provide 0 to 75 lb-in of torque. Both wrenches are accurate to 2% of the dial reading from 20% of the full scale to the full scale. The design of these torque wrenches allows accurate torques to be dialed in regardless of the hand-hold position on the handle.

The precision dial on each driver has two scales. The outer ring of white numbers is the primary scale, and the inner ring of black numbers is the secondary scale. Please see the image to the above right for details. The table to the right lists the increments for each scale. The dial also has two needles. The black needle indicates the torque that is being applied to a fixture. The silver memory needle is moveable and can be used to more clearly indicate the desired torque value.

An accurate set of torque wrenches is essential for assembling high-performance optomechanical systems, and when using ultra-stable mounts, such as our Polaris^® kinematic mirror mounts. Tightening screws to a proper torque and maintaining consistency and repeatability is important because stresses from over torquing can easily distort an optic, warp a flat optical mounting surface, or add excessive stress that will relieve over time and cause mechanical creep.

The TD24 has a range that is optimal for setting an optic without applying excessive force. The setscrew that holds an optic into the mount should only be torqued to approximately 0.38 to 0.75 lb-in in most applications. Less torque will result in an optic being too loose and excessive torque will result in an optic being distorted or damaged.

The TD75 has a range that is optimal for building optomechanical systems. Applying proper torque to components will ensure that your system is built to a repeatable standard and remove the risk of components being loose or over-tightened.

Note:
The wrenches are shipped with the main pointer on the dial lined up with the zero mark and pointing away from the handle. If the main pointer ever does not return to the zero mark, hold the outer dial ring and turn it until they line up again. This will not affect the calibration of the tools. These drivers are shipped with a certification of calibration.

To achieve accurate torque readings the following method may be used:

Rotate the knurled knob counterclockwise (clockwise if you are using the driver in the counterclockwise direction) on top of the crystal until the silver memory needle contacts the main black pointer. Turn the dial bezel counterclockwise until the silver memory needle is pointing to zero. Place the torque driver on the fastener, making sure the tool remains parallel with the fastener. Twist the handle until the desired torque is achieved. When the pressure is released, the black pointer will return to zero, but the silver memory needle will remain at the peak torque reached.

Be sure that the torque wrench is properly zeroed before each use. After each use, make sure the black pointer returns to zero, or the pre-set value. For the most accurate reading, the final turn of the fastener should be made with the torque wrench.

Never use the torque wrench to loosen a tightened screw as it may exceed the maximum torque value of the driver. Never push the needle past the maximum range of the torque driver.