Gunn Machine & Tool Company
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Specialist in on-site, spindle taper grinding for repair and restoration of precision

Accurately measure tool clamping force on machining centers.

Proper clamping force:

Knowing that the tool clamping force meets machine builder specifications is of vital importance. Correct clamping force on machining centers provides a sound connection between spindle and tool. A drop in clamping force can indicate worn or broken springs and other problems with the drawbar. Insufficient clamping force may result in accidents should the tool unclamp during machining.

This critical performance – the tool clamping force – is often never measured after a machine is put into service. Regular verification allows problems to be detected early so maintenance and repairs can be scheduled. As a result, emergencies and unexpected downtime can be avoided. When troubleshooting, ForceCheck allows quick diagnostic verification of drawbar performance. Additionally, ISO 9000 requires periodic verification of a machine’s important accuracy parameters.


Technical Features

          Selectable pound or Newton display
               (any other units are available)

          Selectable "peak hold" of clamping force

          Auto shut-off saves battery life if the unit is left on

          Rechargeable NiMH (Nickel Metal Hydride) battery and charger

          16 character alpha-numeric LCD display

          Calibration data for each measuring bar is electronically stored in the measuring bar  

          Last calibration date is displayed when a measuring bar is connected to the readout

          Analog to digital conversion directly at the sensor improves accuracy

          Software allows new functions and improvements to be programmed into the readout

          Other display languages are available

          Data-logging function available for detailed clamping force analysis

ForceCheck in use



The ForceCheck pull-force gage measures the clamping force of power drawbars on machining centers.

Retention Knobs

For proper measurement of pull-force on standard taper machines, the correct retention knob for the machine must be used with the force-sensing bar. We recommend always using the same retention knob for measuring clamping force.

Basic Operating Instructions

  1. Connect the supplied cable to the readout unit and force sensing bar.
  2. Press the On / Off button to turn the gage on. The display will briefly show "ForceChk" and the installed software version.
  3. If a force-sensing bar is already connected, the ForceCheck gage will automatically zero when turned on. However, if needed, the Zero button can be pressed.
  4. Just as any other tool is clamped, insert and clamp the force-sensing bar in the machine spindle.
  5. After the force-sensing bar is clamped in the spindle, the clamping force is shown on the readout.
  6. To increase accuracy, take three to four measurements, rotating the force-sensing bar approximately 90º for each measurement. Fluctuations between readings are frequently the result of variations in the settling of springs in the drawbar and friction.
  7. When finished, press the On / Off button again to turn the unit off. The display will briefly show "Goodbye" and then go blank.

Other Functions

The ForceCheck readout has several options that can be selected using the Function and Mode buttons

Force: displays only the force on the top line of the display.

F/PkHold: displays the force on the top display line, and the highest force read on the bottom line. This peak value can be reset with the zero button when the force sensing bar is unclamped.

Pound: display clamping force in pounds.

Newton: display clamping force in Newtons.

AutoOff On/Off: With AutoOff on, the readout will automatically turn itself off after approximately 1 minute of inactivity.

Note: the On/Off and Zero buttons do not function when in a menu.


The readout unit has a removable rechargeable Nickel Metal Hydride (NiMH) battery. Because NiMH batteries have no "memory effect", the battery can be charged even when it is not empty. A charger is included with the ForceCheck gage. Charging time for a completely empty battery is approximately 12 hours


To ensure accuracy within design specifications, as is with any other measuring instrument, periodic calibration by the manufacturer is strongly recommended. Additionally, the software in the readout should be updated to the latest revision. Please send back the included product registration card. Sending back the card will allow us to contact you when the gage is due for calibration.

Conversion Factors

1 N [Newton] = 0.102 Kp;

10 kN = 10,000 N = 1,020 Kp 1,020 Kp ~ 1 Metric Ton

1 N = 0.22482 lbs.