Lathe chuck adapter; Fits to plain (flat) back lathe chucks to mount on lathes with 1 1/2"-8 Threaded spindles
Plate Diameter: 6 5/16"; Plate Thickness: 1"
Boss Diameter: 5.12"; Boss Projection: 0.2"
Mounting Hole Type: Counterbored and Unthreaded (3), Threaded (3); Mounting Hole Thread Size: M8 × 1.25mm; Mounting holes are positioned on a 5.59" diameter circle
For intended fitment, boss dimensions and mounting hole placement of the back plate should match the registration dimensions and mounting hole placement of the lathe chuck; Front mount lathe chucks require threaded holes while rear mount lathe chucks require unthreaded and counterbored holes on the back plate