HackSpace – September 2019

Staying keen

TUTORIAL

here’s an old saying that a blunt

knife is more dangerous than a sharp

one. The reasoning behind the saying

is that you need to apply more force

with a blunt knife to make it bite into

the surface, so it’s more likely that you

will slip while you’re using it. The same thing can be

said about most workshop tools, and keeping the

edge on your tools is important if you want to keep

using them effectively. Blunt tools can overheat, slip,

shatter, and can delay or even completely ruin the

project you’re working on. In this article, you’ll be

taking some of the most common workshop tools

and finding out the best way to keep them in working

condition, with the minimum amount of effort.

Sharpening a blade is something that’s easy to do

by hand with a little practice, and there are a few

different tools out there that use automation to let

you get the job done quickly. The simplest method of

sharpening a blade is with a whetstone. A whetstone

is an abrasive stone made wet with oil. Modern

T

Staying keen

Learn how to stay at the cutting edge with your workshop tools

whetstones tend to be double-sided, with a coarse

and a fine abrasive side. The coarse side is used to

grind out more noticeable nicks and blemishes from

a blade, while the fine side is used to hone the edge

to a sharper point. Whetstones are graded, just like

sandpaper. The finer a whetstone, the higher its

number will be, with a coarse stone being 400 or

1000 grit, and finer polishing stones going up above

30,000 grit.

To use a whetstone, apply a little bit of oil to the

surface, and move the blade across the surface so

that the edge of the blade is touching the stone

evenly, with light pressure. For the best results,

always try to move the blade so that the sharp edge

is being pulled along the stone, rather than pushed

onto it. The blade of a knife is usually a V-shape when

viewed end on, so you’ll need to flip the knife over

every couple of strokes so that you sharpen each

side equally, and keep a steady angle between the

stone and the blade. You want to match the existing

angle that the blade makes, so keep an eye on the

edge as you work to see whether you have the knife

tilted too far up or down.

If you have nicks or gouges on the blade, start with

the coarse side of the whetstone and keep working

the blade steadily until you’ve got them out. Once

you have a smooth edge, switch to the fine side of

the stone and continue honing the blade until it’s as

sharp as you need. Some tools like planes, chisels,

and scissors don’t sharpen to an equal V in the centre

of the blade; the sharpest point of these blades is on

the very edge of the metal. For these blades, you

The internet is full of videos where people sharpen

their knives to a razor edge, and then use them to cut

through tissue paper or a single human hair. This is

definitely something that you can do if you have the

time and equipment, but it’s entirely unnecessary for

general workshop tools. A razor-sharp blade is easy

to nick and will blunt quickly on harder materials.

You’ll probably find yourself stopping to sharpen it

every few minutes.

HOW SHARP?

Dr Andrew Lewis

@monkeysailor

Dr Andrew Lewis

is the owner of

Shedlandia.com, a

restorer of old tools,

a fabricator for hire, a

research scientist, and

a founder member of

the Guild of Makers.