Friday, June 21, 2013

V4.25 - Drilling, etc…

Ok, where were we? Lost in Space? In the Twilight Zone? Maybe in a Galaxy Far, Far Away? Nah, we were just playing around in the shop talking about Drill Presses.

Back we go… A conventional DP consists of the following main parts: the base, the column, the table and the head. The ‘base’ supports the machine. Usually it has pre-drilled holes that are for fastening the DP to the floor, a work table or a bench. Some bases have a machined surface that is used to hold a workpiece that might be too large to fit on the regular DP table. The ‘column’, usually made of steel, holds the table and the head and is fastened to the base. Actually the length of this hollow column determines whether the DP is a bench model (it mounts on a work bench) or a floor model (it stands on the floor). Floor DP’s range in height from 66 to 75 inches tall and bench-mounted models range in height from 23 to 48 inches tall. The ‘table’ is clamped to the column approximately midway between the head and the base. It can usually be moved up and down the column, so as to fit odd-sized objects inside the drilling range. The table may have slots and/or clamping ledges in it to aid in clamping and holding fixtures or workpieces. Most tables have a centered locator hole through them and some tables can be tilted, left or right, while some tables have a fixed position only. Some tables have a ready-made “dummy table” which can be easily attached to the table for certain sanding operations.

The term ‘head’ is used to designate the entire working mechanism that is attached to top of the column. The most important part of the head is the spindle. The spindle revolves in a vertical position and has bearings at both ends and is housed inside a moveable sleeve, called the quill. The quill, and therefore the spindle it houses, is moved downward by means of simple rack-and-pinion gearing, worked by the feed lever. When the feed handle is released, the quill is returned to its normal up position by means of a spring. Adjustments are provided for locking the quill and for presetting the depth to which the quill can travel. The quill usually has a stroke (travel length) of 2 to 3 and one-quarter inches on most home shop models. Industrial, or heavy-duty, DP’s usually have a stroke of 6 inches.

An average DP comes equipped with a one-half inch capacity geared chuck with key. This chuck offers the best grip for the most work.

We’ll wrap up this week here and be back with you next week.

Send your questions or comments to: and we’ll see what we can do to help you.

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