STEP CHUCKS Lever operated collet chucking Is fast and accurate. With the Hardinge HLV-H lathe. collet chuck range is ex- tended to 6 ~ diameters by the use ofstandard step eh ucks. A step chuck is exceptionally useful for accurately holding work larger than I " in diameter up to 6 ' in dia- meter. Tubing can be held without crushing or distorting. The step chuck will also hold castings, mouldings. stamp- ings and machined parts rigidly and accurately. The standard ball bearing lever operated collet closer is used to close and open the step chuck. The step chuck is closed by the taper on the periphery seating in the taper of the closer. Many users purchase step chucks, split only.
and then apply the desired steps while the step chuck Is in place on the machine. assuring dead accuracy of the steps. All Hardinge Step Chucks are supplied with pin holes and pins in place for precision machining. This built-in feature provides greater accuracy. convenience and precision results. STEP CHUCK CLOSERS A closer is used with each size step chuck. The closer fits directly to the machine spindle and has a taper cor- responding to the taper on the periphery of the step chuck for closing the step chuck. A step chuck closer is used with each nominal size step chuck to place the closing pressure over the stepped area of the chuck. resulting in greater gripping power and accuracy.
With locating pins applied in the step chuck closer and with clearance holes for the pins drilled in the step chuck, work may be held to predetermined length. ADVANTAGES OF USING STEP CHUCKS Step chucks, developed for precision instrument makers. are a time-proved method of rigidly and accurately holding work. Step chucks take over on sizes above the regular collet capacity, providing collet-I ike accuracy. convenience, and precision results as with coilets. W H EN USI NG STEP CH UC KS: Analytical con- sideration of the grippi ng pressure applied on the work by a step chuck clearly shows one of the advantages of WHEN USING JAW CHUCK S:
Studied consi- deration of the gripping pressure applied on the work by a Jaw chuck clearly shows the disadvantage of using jaw WORK HЈUJ IN ~ T[P T~(8ORE ./ AR~ INDICATE UNlfClflM !lOR[ DISTORTED ~IPPlNG PRCSSURt using step chucks. Note how the gripping pressure is uniformly distributed over the entire circumference of the work. The large gripping area prevents distortion and eliminates marring of the work. chucks for precision work. Note how the localised gripping pressure of the jaws distorts the work. The small area of the gripping surface of the chuck jaws will also mark the surface of the work.