The Folding Hoof Pick: A Hook That Folds Like a Jack-Knife Blade

"My invention relates to improvements in implements for cleaning and removing stones, dirt, and gravel from horses' hoofs; and the object of my improvement is to provide a hoof-cleaner that can be conveniently carried in the pocket, and which shall still be strong enough and have a hook long enough for effective use in removing clay, fine gravel, and other matter lodged between the hoof and shoe." "The hook-blade A is made with a long, thin, curved hook, of the shape clearly shown by drawings as being best adapted for reaching far under the shoe, and is hinged, like the blade of a jack-knife, to a handle formed of the side plates, B, and spring C."

**Hook.** Cut 16 cm of 12 × 5 mm mild steel flat bar, the section the notebook shows surviving a hard pry. Heat the top 7 cm with the torch, clamp the bar in the vice beside a length of steel tube and bend it round the tube into a curved hook; let it cool, then file the tip to a blunt point and round every edge. Drill a 5 mm hole 1 cm from the straight end for the pivot. **Handle.** Cut two spatulate side plates 11 cm long from aluminium sheet, the narrow end as wide as the hook. Drill and saw out the centre of each, leaving a rim 8 mm wide. Rivet a strip of spring steel between them along the back so it presses on the hook's straight end. Bolt the hook between the plates through the pivot hole with a nut, so it swings out and the spring holds it open or shut. **Test.** Nail a horseshoe to a hardwood board with horseshoe nails and pack modelling clay and a few small stones inside its rim. Time how long the pick takes to clear it. Hang the spring scale on the open hook's tip, pull to 100 N and check the hook springs back.

**Edward O. Davis** of Youngstown, Mahoning County, Ohio, filed US 274,570 on 30 August 1882; it is dated 27 March 1883. He wrote: "I am aware that hooks have been heretofore made hinged to a handle"; his claim is the hook with the open-centred spatulate side plates and the spring. **Honest limits.** A bolt stands in for Davis's pivot-rivet. The notebook treats the hook as a straight beam fixed at the hinge. Forces are examples; your clearing times and the spring-back check are the result.