In a workshop of almost any description, the ability to drill a hole which is dead square to the horizontal plane is crucial, so the drilling machine, or pillar drill, is one of those essential pieces of equipment that must be included at the outset. As well as its primary function of drilling holes, the addition of optional attachments increases the versatility of the machine; for example, to cut mortices. Using a drum sander in the chuck will also enable the pillar drill to be turned into an effective sanding machine for concave curves, though it is recommended that a suitable dust extractor is used as well.
The effective height of the machine is governed by the ‘chuck-to-table’ distance as this is the maximum dimension that can be fitted vertically under the chuck. A taller workpiece could be drilled, but this would entail moving the table through 90° in order for the workpiece to stand on the machined base. Similarly, the widest workpiece that can be drilled is determined by the ‘throat’ dimension, which is the distance from the centre of the chuck to the column. However, on certain machines, notably in the Hobby range, the head is able to tilt through a prescribed angle as well as slide back and forth, which greatly increases the ‘throat’ capacity and generally makes the machine more versatile.
If the workpiece to be drilled is generally quite tall, then a floor standing drill is required. Conversely, smaller jobs may only require a bench mounted drill, which means that there is usually adequate storage room underneath. Bench mounted pillar drills are still very heavy and require a substantially constructed unit to support the weight. Due to the weight of the individual sections, we would strongly advise that all pillar drills are assembled by more than one person!
Key Features of a Pillar Drill
The machines are relatively simple and are centred around a substantial steel column; onto one end is attached the motor, drive belt system and chuck. The other end of the column is securely located into a heavy cast iron base and between the two is the horizontal table, which can be moved vertically by means of a rack and pinion mechanism operated by a convenient handle.
Motor & Drive Belt System
This unit is the cornerstone of all drilling machines and consists of an induction motor at the rear, situated behind the column with the chuck directly over the table. The chuck speed can be varied by lifting up the interlocked cover, releasing the tension on the drive belt which is then re-positioned over the most appropriate pulleys. The chuck is contained in a precision machined quill within the headstock and there should be virtually no play in it even when extended out to three-quarters of its travel.
The surface ground table can be raised up and down the column by means of a rack and pinion mechanism, though there is also an option on many machines to tilt it, which means that the workpiece can be drilled at an angle other than 90°. Many tables, particularly in the Trade and Engineer ranges, also have grooves cast into the surface around the edge to enable coolant slurry to drain away efficiently. All tables also have diagonal slots or grooves allowing a machining vice or additional pillar drill table to be bolted to it.
The column is a hollow cylinder of surface ground steel, ensuring that the table’s rise and fall is very smooth making the height adjustment a light task.
This is a robust, heavy piece of cast iron where a flat horizontal surface has been ground. Moving the table sideways allows a taller workpiece to be drilled by standing it in on the base. The casting for the column is bolted securely onto the base at the rear and there is also the facility to bolt the drilling machine to either a bench top or floor.