4 Jaw Scroll Chuck with locking screws for using on a lathe with reverse direction. Based on our best selling Viper range of chucks, the Nexus3R has a jaw mounting compatible with Record Power, Nova and Robert Sorby Patriot. This will be of particular interest to any owners of those chucks looking for a second chuck and wanting to be able to continue using any jaws they already own. A 4″ sized scroll chuck, with the jaws adjusted by a geared mechanism for simple one handed operation. Self centring, high precision design. The fully enclosed body of the chuck prevents dust and chips from getting inside and plugging up the teeth of the gear mechanism. Ideal for Midi sized lathes and upwards. Supplied with standard dovetail jaws, wood screw, T-bar 8mm Square drive for scrolling the jaws and T-handled hex key 4mm for removing the jaws. The locking screws allow the chuck to be locked onto the lathe spindle. Reverse direction should only be used when the chuck is mounted directly onto an M33 x 3.5 spindle thread. It should not be used in reverse when using a thread adapter. NEXUS3R Specification Direct Mounting Thread: M33 x 3.5 Chuck Body Diameter: 95mm Standard Jaws Expand from: 53mm to 80mm Standard Jaws Contract from: 68mm to 41mm Jaw Travel: 27mm Jaw Scrolling: 8mm Square Drive Weight: 2165g THIS LATHE CHUCK MOUNTS DIRECTLY ONTO A LATHE WITH A SPINDLE THREAD SIZE OF M33 X 3.5. PLEASE CHECK THE SIZE OF YOUR LATHE SPINDLE BEFORE ORDERING. Optional thread adaptors are available to mount this chuck onto a lathe with a spindle thread size of : Thread Size / Part number 3/4" x 16tpi / VIPERID. 3/4" x 10tpi / VIPERIK. 1" x 8tpi / VIPERIA. 1" x 10tpi / VIPERIF. 1" x 12tpi / VIPERIG. 1.1/8" x 12tpi / VIPERIM. 1.1/4" x 8tpi / VIPERIE. M18 x 2.5mm / VIPERIH. M20 x 2.0mm / VIPERII. M25 x 2.0mm / VIPERIJ. M30 x 3.5mm / VIPERIN.