Originally Posted by redbugsullivan

Sweet Caroline and Charlee, you're all that and a bag of chips!
So, the top clamp rotary attachment holder (what a mouthful) fits on my treadle Alvah (National) which is quite handy because it came with NO attachments besides the straight foot. I am feeling rather silly because both, the Reversew and Alvah, came from the same home, one owner. The bulb is glowing a wee bit brighter now.

Tentative newbie showing: it is a back clamp, low shank that becomes a top clamp with the additional piece. Right?

The end of the bar has a taper milled into it to ensure the foot does not slip down when the back clamp is engaged. So, why is there a hole drilled through the bar above the attachment?