John K Jordan
>>>Why would you need the brass hat?
I believe the flat is intended to bear against both sides of the flute to keep the gouge aligned horizontally while sharpening. A simple bolt bearing inside the flute might make it easy to misalign the gouge and give a unsymmetrical grind. I don't remember if I ever knew or guessed the reason for the wider hat brim. The second one from G. Lucas provides more space to hold larger diameter gouges. I suspect these pieces are made of brass instead of steel to avoid marring the flutes.
It would be very easy to make a new piece from brass any thickness or shape for nearly any diameter gouge. However, from the description of "orientating the clamping pad" and making sure the "brass rod is perpendicular to the tool" makes me think there is more than one design. The one I've had for a decade or so has no brass rod so it must be an earlier design. I see from the Tormek site the latest jigs are made differently. Perhaps Doug's original post describing the jig as an SVD-180 is incorrect or his has been upgraded or modified. Without more information I give up! Maybe he as it figured out by now.