"Human nature is bad. Good is a human product A warped piece of wood must be steamed and forced before it is made straight; a metal blade must be put to the whetstone before it becomes sharp. Since the nature of people is bad, to become corrected they must be taught by teachers and to be orderly they must acquire ritual and moral principles." ?Sun Tzu
No, neither of these will work. The tightening of the bolt is what holds the hook and shear together. There is "A LOT" of force here, over 1000 lbs. on the pushrod to the shear plate. Its got to be one piece. The fine thread adjustment is finicky enough, coarse threads would be terrible.
I know McMasterCarr don't have it. The Fastenall store near me is run by idiots. I'll go to Fastenal when I get to the cities sometime.
Not a shoulder or stripper bolt, per Karl's original. Threaded portion and ground portion are same diameter. I looked for a while, couldn't find one like that. They probably exist, but who knows where. Were it me, I'd hit my favorite fastener vendor and see what they could come up with.
Otherwise, it looks like he'll have to make one. It might save a lot of work if he could figure out how to make and fasten the head onto O-1 or A-2 ground stock. Just thread as needed before heat treat.
Shoulder bolts are intended to provide a fixed length "axle" for a rotating tooling component. I gather that Karl's application requires tension adjustment for the pruner jaws, hence the same diameter fine pitch threads.