In terms of sharpening facilities no other item of workshop equipment in my estimation
is more widely catered for than the humble twist drill. This probably due to the
large number of trades that will use this tool, ranging from the DIY exponent through
to the experienced tool maker, passing on the way such trades as builder, plumber,
cabinet maker, etc. etc.
Sharpening by hand
First, let us consider the possibility of sharpening drills by hand. There are those
who consider this is a perfectly acceptable approach and for a few in who sharpen
drills on a regular basis, just possibly it is, though I have my reservations. Two
things are being aimed at when sharpening a drill, these are, it cuts freely, and
to size. The first is very easy to achieve, the second, very much more difficult.
For the metalworker, there is no point in having a set of drills in 0.1mm increments
if the 7.6mm drill produces a hole 7.8mm diameter.
Whilst some just may be able to meet the requirements the vast majority of home workshop
owners, who will only sharpen a drill occasionally, have very little chance of mastering
the art. A drill grinding jig is therefore in my estimation a necessity, and one
that cannot be done without on the basis of cost as they are very reasonably priced.
Drill grinding devices
The devices for carrying out the task are available in a range of types,but these
pages are more about the aims and how these are achieved. I am doing this using the
common drill grinding jig used with an off hand grinder, Photograph 1. These are
not expensive, so providing the user is prepared to spend time getting the essential
knowledge, they are ideal for the small workshop. I will also discuss later the four
facet method of sharpening drills.
The basic drill grinding jig
Unfortunately, these often get a poor reputation regarding there ability to produce
a usable drill, but this is almost certainly due the user not fully appreciating
the requirements. In fairness, this is not easy, and the very poor instructions
frequently supplied do not help, can even hinder if followed.
The basic idea for the drill grinding jig being discussed here has been around for
very many years, typically that shown in Photograph 2. This is the "Reliance" jig
that was available from early in the 20th century and really is very little different
to the modern day version.