Designing a Jig for Drilling Holes in a Pin

PROBLEM:

Design a drill jig for drilling two holes of 5mm dia in a pin as shown in the fig below:

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40 20 40

CATIA DRAWING OF PIN

Steps for design and construction of a jig

Whether a fixture or a jig?

Though in our case it is specified to design a jig but in general since a hole has to be drilled precisely at a particular location within tolerance a suitable drill – guide will be necessary. So it has to be a jig.

Positioning and orientation

Since two diametric through holes have to be drilled perpendicular to the pin axis, and the drill – axis in the machine is vertical, the suitable orientation of the job in the jig and against the drill axis will be horizontal as shown in fig. below:

Locating the workpiece in the jig and w.r.t. the drill – axis

We can utilise the cylindrical hole in the jig for location purpose. A pocket of 5mm depth holds the pin and the through hole helps in location. LEG POCKET HOLE

Base for jig to wear drilling forces

Since the heavy drilling force will be generated a proper arrangement to wear this force has to be provided. For this legs are provided in the jig as shown in the above figure.

Clamping:

Clamping system should be, as far as possible, simple and quick but also need to be strong, rigid and stable. Clamping should not also obstruct or hamper blank’s loading and unloading as well as machining work. Keeping all such factors a C-Washer and a bolt may be considered for clamping as indicated in figure below

Tool guidance

Since it is drilling a deep hole, tool guidance must be provided as indicated in Fig. below which also shows the slip type bush for replacement of the bush....