re: Hand Plane Tap Hammer - Part 1

Very nice plane hammer, I gotta make me one of these. The quick connect bolt cap might become a problem with the hole, some irons are not very wide up top and either they could go in the hole - maybe get stuck, or deflect on the hole rim for unwanted movement. 
I like the bulbous handle, can be used for a good smack on a stuck wedge.
Great work, got me thinking about making mine.
I tried a Google search for 3/8 - 16 carriage head bolt, got a page full of them. Give it a try.