Half inch, on mine... Yeah, Rick. I was amazed that it moved. I like your captured bolt idea but I think the spring is easier. Also, the Woodward machine I have had grease zerks as delivered, a nice touch.
I finished the spreader/depth guide and made the T handle for the depth bolt yesterday and now we're on to the motorization project. I started a thread in the Technical General section to glean advice on that.