Craft Knife: Doniger's Hinged Handle and Reversible Blade

A knife for model carving and fine cutting, by Sundel Doniger of New York, founder of X-Acto (US 2,463,682, filed 1945, granted 1949). The handle is two shell-like metal halves pivoted at the rear. A thin blade with a slot in its middle drops over a small 'staple' pressed out of one half; closing the other half pushes a tongue into the staple and locks the blade solid. Swing it open to change the blade or turn it end for end: the spare end rests inside the handle. The patent gives no sizes or metals. Mild steel sheet, the rivet, the spring steel blade and the sizes are ours. The picture: Figs. 1 and 2 of the patent.