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User's Guide for the Gizmo Torque Meter
Click here for Winder Guide

The novel design of the Gizmo Precision Torque Meter provides the model flyer with an easy-to-read and accurate torque measuring instrument which he or she can use to get the maximum performance from a rubber-powered model airplane. This Torque Meter features a Bar Graph style of read-out with an effective scale length of 6 inches for a maximum torque reading of 24 oz-in.

This means that accurate measurements down to 0.2 oz-in. may be made. The low internal friction, due to the ball bearing-mounted spindle, keeps the hysteresis to less than 1%.

Long-term accuracy is maintained by using a coil spring made up of a 62" length of .054" wire which is stressed to only 50% of the recommended maximum tensile. The spring is protected from overstress by a slip-clutch safety.

 

— How It Works —

The Torque Meter is a co-axial design with the Inner (indicator) Cylinder rotating inside an Outer (scale) Cylinder. The Outer Cylinder is attached to the Winder and transmits torque via a coil spring to the Inner Cylinder. The Inner Cylinder has, on its surface, a series of diagonal lines separated by backgrounds of blue, yellow and red. The Outer Cylinder features a narrow window with three scales along one side. 0 to 8 oz-in. is on a blue background, 8 to 16 oz-in. is on a yellow background and 16 to 24 oz-in. is on a red background. As torque is applied to the rubber motor by the Winder, a blue bar is seen to rise in the window. The torque value is read off the scale on the corresponding blue background. When the torque exceeds 8 oz-in., a yellow bar is seen to rise and the torque value is then read off the scale on the corresponding yellow background. Torque values exceeding 16 oz-in. show a rising red bar and the torque value is read off the scale on the corresponding red background. In case of color blindness, each scale is labeled a, b and c, with a corresponding letter appearing at the bottom of the window to indicate which scale to read.

There is a friction clutch between the output (hook) shaft and the Inner (indicator) Cylinder which allows the zero point to be adjusted if needed.

— Mounting the Torque Meter —

1.
Remove the Rubber Motor Hook if it is attached to the Gizmo Precision Winder by first loosening the Thumbscrew on the Hook Retaining Collar and sliding the collar forward off the shaft and then pulling the hook tang out of the hole in the output shaft.
2.
Mount the Hook on the output shaft of the Torque Meter by reversing the above procedure.
3.
Fit the Torque Meter to the Gizmo Winder by sliding the unit onto the Winder's output shaft as shown in Diagram A. Line up the holes and insert the Hairpin Cotter until it snaps in place.
4.
Before winding your rubber motor, make sure that the Torque Meter is at Zero (the word ZERO should be seen in the window). If it is not, follow the next set of instructions.

— Zero the Torque Meter —

Grasp the Inner (indicator) Cylinder between the thumb and forefinger at the location shown on Diagram B. Rotate the output shaft by twisting on the Hook Collar in a direction so as to bring the instrument to Zero. Turn it a small amount and then release your grip on the Inner Cylinder to see what effect the action has on the zero point. Repeat this procedure until the instrument reads Zero. When this is properly done, the word ZERO appears in the window and the black line separating the red from the blue background is exactly on the scale's zero number (see Diagram B).

Please note that this slip clutch is designed to be hard to turn so that the zero doesn't change when one is manipulating the Torque Meter's output shaft while disconnecting it from the model.

 

— Important Notes —

1.
The Torque Meter is designed to ONLY transmit torque in the CLOCKWISE direction as viewed from the handle of the Winder (This is the standard winding configuration for most models). Winding counter-clockwise to torques over 8 oz-in. will cause the spring safety system to slip and change the zero setting. Remove the Torque Meter to wind CCW.
2.
The chart "Estimated Breaking Torque for Tan II Rubber" on the Winder counter is to be used for quick reference only, as the characteristics of rubber can vary significantly from batch to batch. For more accurate data on breaking turns and torque you must test the rubber you are using.
3.

If you explode a motor at high torque readings, the resulting inertia of the Torque Meter going to zero may cause the spring protection safety to slip and shift the zero reading. If this happens, check the zero setting and adjust if needed.

We would emphasize here, that it's extremely important to tighten the Thumbscrew securely and check it regularly.

Click here for Winder Guide

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