This high quality aluminum flexible coupling can be used to connect your NEMA23 stepper motor to your lead screw. The flexibility will help with any misalignment there might be between the shafts.
Shaft: 6.35mm x 8mm
OD: Outer Diameter: 19mm
6.35mm fits a NEMA23 stepper while the 8mm fits our ACME Lead Screws.
Main dimensions: d1=6.35mm, d2=8mm, D=19mm, L=25mm