DIY Rotary/4th using Grizzly/Phase II/equivalent

I have a question for those of you who have made your own 4th using the Grizzly/Phase II/equivalent table: do you happen to remember what the diameter of the worm shaft is?

I am waiting for my table to arrive but don't want to wait until it gets here to order the coupler for the stepper shaft.

Hi,

I have the following and it has a 12mm shaft diameter.

Grizzly.com

Thanks!