Late Model PTE Setting Gage Calibration

Recalibration of the setting gauge may be required to maximize the holding power of the Lucas PTE tool holding mechanism for any one of several reasons. The more common reasons are:
 

1. If the spindle taper is reground, recalibration is DEFINITELY required.
    
2. When a collet is replaced, recalibration MAY be required.
    
3. If the internal components of the PTE are rebuilt or replaced, gauge recalibration IS required.
    
4. Minor gauge recalibration MAY be required shortly after a major PTE rebuild to compensate as new parts 'seat in'.
   
    

The recalibration procedure is as follows:

1. Using the drawbolt adapter gauge furnished with the machine, set an adapter to the proper depth in a tool arbor and insert it into the spindle. The adapter MUST be 'wrench-tight' into the arbor. Use the tapered expansion plug located in the rear of the adapter to expand the adapter threads until a tight fit is obtained. An adapter that is too loose will result in an incorrect calibration of the setting gauge, and will produce inconsistent tool holding capability.
    
2. To test the holding power of the Power Tool Ejector, obtain a pry bar approximately three (3) feet long and attempt to pry the arbor out of the spindle, using due caution not to damage the spindle nose.
    
3. Using a dial indicator, check the amount of arbor 'spring' that can be obtained by prying. The 'spring' should not exceed 0.002 inches. This is the amount of 'spring' inherent in the collet, and does not indicate the tool is loose. Normal machining operations, including heavy back facing, do not exert the amount of pull obtained by this pry test.
    
4. If more than 0.002 inches of 'spring' is obtained (or if the arbor can actually be pulled out of the spindle) change the depth setting of the adapter drawstud and repeat the pry test until suitable results are obtained. It is extremely important to make the 'trial' adjustments in steps of no more than a few thousandths at a time until the proper setting is obtained. The range of adapter settings that will produce maximum holding power (and minimum 'spring') is rather small, and is generally found with the adapter setting no deeper than 0.020 from the point at which the arbor is first gripped snugly.
    
5. Correct the taper gauge to suit the new adapter drawstud depth setting. If the new adapter stud setting is deeper (into the gauge) than previously, the top of the gauge may simply be ground to match the end of the adapter stud. If the new setting is found with the adapter stud extending out of the end of the gauge, the gauge may be corrected by grinding the I.D. of the gauge at it's large end and pressing in a sleeve with a slightly smaller I.D.. This will cause the gauge to seat higher on the male taper of the arbor, allowing the top of the gauge to be ground to match the new adapter drawstud depth setting. Alternately, the gauge may be chrome plated. This will 'raise' the gauge several thousandths, and may be enough to allow re- grinding without the need for a gauge bushing.