[app. the same word as BUR sb.; at least having some notion of roughness derived from it: but usually spelt burr, and therefore here treated apart.]
1. A rough ridge or edge left on metal or other substance after cutting, punching, etc.; e.g., the roughness produced on a copper-plate by the graver; the rough neck left on a bullet in casting; the ridge produced on paper, etc., by puncture.
1611. Florio, Bocchina … that stalke or necke of a bullet which in the casting remaines in the necke of the mould, called of our Gunners the bur of the bullet.
1784. E. Darwin, in Phil. Trans., LXXV. 5. A bur made by forcing a bodkin through several parallel sheets of paper.
1837. Whittock, Bk. Trades (1842), 214. The scraper … for rubbing off the burr or barb raised by the graver on the copper plate.
1846. Print. Appar. Amateurs, 13. [In type founding] when the waste piece of metal called the ‘break’ is broken off, the burr that is left is planed away and forms this groove.
1876. Athenæum, 25 Nov., 693/3. Burr … is caused by the tearing up of the copper by the needle or burin. A ragged edge is left which holds the ink and gives a rich velvety effect.
1879. Cassell’s Techn. Educ., IV. 117/2. A burr left at the hinder end of the thread [of a screw] which ‘ragged’ the wood.
2. Technical senses of obscure origin. [? With notion of ‘something rough,’ or of ‘tool for removing roughness.’] a. short for burr-chisel, burr-drill, burr-saw: see 3. b. (See quot.).
1794. Rigging & Seamanship, I. 150. Burr, a triangular hollow chissel, used to clear the corners of mortises.
1833. J. Holland, Manuf. Metals, II. 145. In the making of screws … workmen … use what they call a burr, or burring tool…. The burr is a square piece of steel … having in the centre a hole screwed as accurately as possible with a square thread or worm.
3. Comb. burr-chisel, a three-edged chisel used to clear the corners of mortises; burr-cutter, burr-nipper, nippers for cutting away the burr from a leaden bullet; burr-drill, a dentist’s drill with a serrated or file-cut knob or head; burr-gauge, a plate perforated with holes of graduated sizes, for determining the sizes of burr-drills; burr-saw, a small circular saw used in turning.
