When I was starting out with pillar drills, I found all of the terms for the different parts and measurements really confusing. This article is designed to help you if you are trying to choose a drill and need to understand what all the terminology and jargon means.
Parts Found on Pillar Drills
- Drill head — the assembly that makes up the chuck, spindle, drill bit, motor and pulleys.
- Base — the heavy “foot” of the machine that is bolted to the floor in the case of a larger pillar drill or the workbench in the case of a smaller bench-mounted drill.
- Column — this is the vertical pillar that gives the pillar drill one of its names (confusingly, its other common names are “bench drill” and “drill press”).
- Spindle — the vertical axle that is in line with the drill bit and connects the chuck to the drill head.
- Chuck — the assembly that fits onto the spindle and holds the drill bit.
- Table — this is sometimes little more than a ledge in smaller bench drill models. It’s the support for the work piece to be drilled, and is attached to the column some distance below the head and above the base. Tables can be rectangular or round, and some can be tilted to allow angled drilling through a work piece. Pillar drill accessories can be bought to clamp or cradle work pieces in various angles.
- Depth gauge — a setting that enables the bench drill to drill a hole part-way through a work piece.
The Meaning of Measurements in Drill Specifications
- Throat distance — this is the measurement from the nearest edge of the pillar to the spindle centre.
- Swing — this is a common measure of the capacity of pillar drills and is defined as twice the throat distance, or to put it another way, the maximum size of disc in which you can drill a central hole.
- Spindle taper — this defines the shape of the end of the spindle. There are long, short, female and male types. The chuck needs to be compatible with the spindle taper.
- Collar Diameter — this is the outer diameter of the collar or chuck assembly that holds the bit.
- Chuck size — this is the diameter of the inner opening of the chuck assembly, so it defines the maximum size of bit stem that the drill can take. Because of this it is also known simply as the drilling capacity.
- Spindle travel — this is the amount by which the spindle can be lowered or raised vertically and defines the maximum depth of hole you can drill in one pass.
- Maximum distance spindle-to-table — this distance defines the deepest work piece that you can get onto the table.
- Maximum distance spindle-to-base — this is similar to the above and defines the maximum depth of work piece you can drill with the table removed.