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The general-purpose drill line from Dormer Pramet includes the Precision Twist Drill brand of Silver & Deming drills. These reduced-shank drills deliver versatility and reliability.
The Precision Twist Drill R56 features a ½ inch diameter round shank suitable for use with ½ inch chuck portable drills. The common flute and overall length allows for minimal adjustments for drill presses. It is ideal for drilling a wide range of materials of low to medium tensile strength.
The Precision Twist Drill R57 features 3 flats on the ½ inch diameter shank for a more positive non-slip hold.
The Precision Twist Drill R56CO is manufactured from premium cobalt steel for increased hardness, wear resistance and heat resistance. It features a 118° self-centering split point for accurate positioning and easier penetration. The R56CO is the ideal drill for tough, high tensile strength materials that generate higher cutting temperatures, such as high alloy steels, ferrous castings, stainless and other difficult-to-machine materials.
Related Glossary Terms
- alloy steels
alloy steels
Steel containing specified quantities of alloying elements (other than carbon and the commonly accepted amounts of manganese, sulfur and phosphorus) added to cause changes in the metal’s mechanical and/or physical properties. Principal alloying elements are nickel, chromium, molybdenum and silicon. Some grades of alloy steels contain one or more of these elements: vanadium, boron, lead and copper.
- chuck
chuck
Workholding device that affixes to a mill, lathe or drill-press spindle. It holds a tool or workpiece by one end, allowing it to be rotated. May also be fitted to the machine table to hold a workpiece. Two or more adjustable jaws actually hold the tool or part. May be actuated manually, pneumatically, hydraulically or electrically. See collet.
- hardness
hardness
Hardness is a measure of the resistance of a material to surface indentation or abrasion. There is no absolute scale for hardness. In order to express hardness quantitatively, each type of test has its own scale, which defines hardness. Indentation hardness obtained through static methods is measured by Brinell, Rockwell, Vickers and Knoop tests. Hardness without indentation is measured by a dynamic method, known as the Scleroscope test.
- shank
shank
Main body of a tool; the portion of a drill or similar end-held tool that fits into a collet, chuck or similar mounting device.
- tensile strength
tensile strength
In tensile testing, the ratio of maximum load to original cross-sectional area. Also called ultimate strength. Compare with yield strength.
- twist drill
twist drill
Most common type of drill, having two or more cutting edges, and having helical grooves adjacent thereto for the passage of chips and for admitting coolant to the cutting edges. Twist drills are used either for originating holes or for enlarging existing holes. Standard twist drills come in fractional sizes from 1¼16" to 11¼2", wire-gage sizes from 1 to 80, letter sizes A to Z and metric sizes.
- wear resistance
wear resistance
Ability of the tool to withstand stresses that cause it to wear during cutting; an attribute linked to alloy composition, base material, thermal conditions, type of tooling and operation and other variables.
