Powered gaging of tapered pipe threads is done with tapered Thread Gage Members (TGMs) that have gaging notches ground into them, the notches serving the same purpose as they do with hand gages. But the outsides (or the shanks) of the gages are adapted so that they will work with the New Vista Compliant Toolholders that are always required in powered pipe thread gaging.
The technique in powered gaging of tapered threads is not materially different than that in hand gaging: the gage is run into or onto the thread to the point of stall; and then if the thread is good, the gaging flat (the gaging notch in a single-flat gage) will be expected to be between one turn high and one turn low relative to the end of, or the face of, the part.1 So for powered thread gaging, you will need two depth sensors on your New Vista Thread-Verification Unit (TVU).
So in operation, the TVU simply runs the TGM in to stall. If the part is good, the depth sensors will have indicated that the gage has gone in (or on) far enough, but not too far.
When New Vista quotes a tapered pipe thread application to a customer, unless otherwise stated, the thread-verification test is presumed to be the single-step process, where this is a single run onto (or into) the thread, and the torque level employed corresponds to what would be expected of hand gaging. But occasionally a customer’s parts are sufficiently rough or dirty, that it may pay to use the 2-step process, which works like this: First the TGM is run in (or on) to stall at a high torque level, for a ‘seating’ (or conditioning) cycle. Then the TGM is backed away slightly and then run in (or on) a second time for the ‘gaging’ cycle, at a torque level that is lower, the level that has been selected to correspond to what would be expected of hand gaging.
A hand torque wrench can be employed to run torque tests (on a quantity of production parts) that will indicate whether the 2-step process will be needed or not.
Compliant toolholders are essential for pipe thread gaging. Compliancy allows the TGM to follow the existing thread in the part, regardless that the thread be off-center or off-angle.