Built-Up Shaft Collar: Two Washers Welded to Four Nuts, a Set Screw in One Nut, No Machining (Dalrymple, 1939)

"Preferably, I use as plates standard washers of suitable dimension, and I use as blocks standard nuts." "Inasmuch as the space between the plates is not sufficient for the convenient manipulation of an ordinary wrench, I use socketed set screws for securing the collar to the shaft."

Use plain steel washers and nuts, not zinc-plated ones. Wire-brush them clean. Grip a 16 mm round bar upright in the vice. Slide one washer onto it, stand four M8 nuts on the washer round the bar at quarter turns, each with a flat down and its hole pointing at the bar's centre and its inner face against the bar. Put the second washer on top and squeeze the stack with the C-clamp; check with the square that the washers are parallel.

Wearing the helmet and gloves, tack each nut to both washers with a short fillet weld at its outer corner, keeping the arc away from the bar. Let it cool, lift the collar off the bar, and run a fillet along both ends of every nut on both washers. Chip and wire-brush the slag. Run the set screw in and out of one nut to clear any spatter from its thread, and file the bore ends smooth.

Run an M8 x 8 cup point socket set screw into one nut from outside. Slide the collar onto the shaft to its place and tighten the screw with the hex key between the washers. Try to slide and turn it; it must not move.

**Ferdinand H. Dalrymple** of Bedford, Ohio, US 2,163,315, dated 20 June 1939, filed 2 November 1937. He claimed "opposed spaced plane plates formed with coaxial bores for the reception of a shaft, transverse spaced internally-threaded blocks welded to the opposed faces of the plates and serving as the sole means for holding the plates in relatively fixed positions, and set screws engaging the blocks". His Figs. 8 and 9 use standard square nuts and socketed set screws; we use hex nuts, as his Figs. 1-5 allow "standard nuts". His patent also shows special blocks, flanged plates, three-plate and split forms; we build the simplest. He gives no sizes for this form; every size here is ours.