S & D Twist Drills: A Top Choice When You Want Flexibility

The advantages of using large twist drills with a common diameter shank are cost effectiveness and simple consistent setup for various jobs. S & D drills from the National Twist Drill brand are available from ½” to 1 ½” diameter in different styles. They come in general purpose, split point for easy centering and Cobalt for heavy duty applications. Tools are available with round and flatted shank styles, although the flatted preference is usually selected for hand drilling.

Silver & Deming are the names of the inventors of this common shank style drill and they were manufactured and sold by their company, which patented the design. The other style shank frequently selected for larger drills is the taper shank which fits into a tapered holder for a given range of sizes.

Drill press applications, particularly for long runs or heavy drilling, normally require the use of taper shank style holding for convenience. This type of connection can improve the holding mechanism to produce better location of the initial drilling penetration or higher torque control for heavy duty drilling.

So why would you choose to select ½” round shank drills for holes from sizes ½” to 1 ½”?

The common thought process of most mechanics and machine operators is to use S & D style drills for portable hand held drilling not for drill press or CNC machining. Selecting these drills can save money in the initial cost of the drill and because the overall and flute lengths are identical for all diameters the programming or fixture setup is simplified.

You can choose the general-purpose style for routine work or the split point design for concentric hole locations. Heavy-duty cobalt is also available in some sizes. Selection of this style will require evaluation of the material being drilled, the depth and size tolerance required, and the rigidity of the machinery. Choosing this style drill for the right jobs can save money and improve efficiency. Contact Regal to learn more about choosing the best twist drill for your needs.