The machine I learned on might have been an old 27 - for sure it was a hand crank. It has been just shy of 60 years. I also remember it was mounted on a couple 2X4s and then set on one of those old school desks that went in rows. The seat was in front but I stood behind there and hand cranked it. Then awhile back I picked up an old 27 mounted on 2X6s. Goes to show about anything is vintage appropriate... They improvised as needed, too. Maybe some old Yankee ingenuity was handed down to us.