I drew this fuller tool plan as a place holder in my “Tools to Make” file. From time to time I actually pick an idea out and build the tool. This one will be pretty far down on the priority list as I already have a variety of fullering devices which work quite well. But you never know when this type might seem like just the thing to use. The measurements are just guesses and there may be better choices. Also, I didn’t take the time to draw the dressed radius lines on the top and bottom blades. Probably I would start with just grinding slight front and back edge radii and creating a slight concave gap between the blades so the work piece tends to seek the same centering position. Then I’d modify the edges after observing the results.
Mostly I use gate, swing arm, type fullers (which some call guillotine fullers even though the blades don’t move in the same vertical plane) in the power hammer. Occasionally I use the Smithing Magician, which seems to me to be a true guillotine fuller, or similar constructions in the fly press or hydraulic forging press. Only as a last resort do I use a hand hammer with a anvil hardy fuller tool.