THE EXPANSION PLUG is sized to suit the measurement of a specific dimension. When retracted, it will easily enter even an undersize bore. When allowed to expand, it will engage the bore on its true diameter.
Because of its unique design, the Comtorplug is SELF-CENTERING and SELF-ALIGNING when expanded in the bore. Its built-in spring loaded pressure assures constant, uniform gaging contact. Thus, accuracy is assured independently of differing operator skills.

 

QUICK ASSEMBLY INTERCHANGING expansion plugs. Takes less than two minutes. With Amplifier cover halves loosened, insert plug as far as possible, turn it 90° and refasten cover halves. Gage is ready to be mastered.

THE AMPLIFIER responds to the linear displacement of a cone-tipped plunger which is accurately positioned by the amount of expansion or retraction of the plug and magnifies the motion so that it is clearly indicated on the display, showing the amount of variation, plus or minus, from the mean dimension. The Amplifier has a built-in shockproof movement to withstand hard, prolonged shop usage without losing accuracy.

THE REFERENCE RING is made to the precise size representing the mean diameter of the bore to be checked. This all adds up to a very straightforward system which permits rugged construction without sacrificing sensitivity and requires no adjustment beyond setting zero.
Gaging action is simple. Retract the plug / enter the bore / release and settle the plug / read the size variation.

QUICK MASTERING. Retract plug, place in master ring, release retraction button. Loosen the bezel lock slightly, rotate the dial until zero aligns with the indicating hand. Tighten lock. Work the plug several times to assure repeat readings. You're ready to gage.