9

Maker’s Toolbox: Bench grinders

TUTORIAL

Sharpening tools and shaping metal

ssentially, bench grinders are just

tools for spinning grindstones, and

these grindstones are for gently

shaping metal. They’re commonly

used for getting blunt tools back to full

sharpness, but they’re not a one-stop-

shop for instantly putting an edge on a tool.

When using a cutting blade, the edge gradually

dulls. When an edge is slightly dull, it can be honed

back to full sharpness using either a very fine grit

or a sharpening steel. This works by making fine

adjustments to the very tip of the blade. However,

at a certain point, this just won’t work. If the blade

has become too dull, these fine adjustments won’t

be enough to put a sharp edge on. Also, if there’s a

chip in the edge, then you’ll need to remove this chip

before putting the edge back on. In both these cases,

you need to grind a larger amount of metal off the

tool in order to get a sharp edge. It’s not essential to

use a bench grinder to do this, but bench grinders

are an easy and accurate method for doing this.

Obviously, the power tool aspect of them means that

the electrical motors are doing the hard work, but this

also means that you can keep much greater control

over the grinding. Using a proper tool rest and an

angle-setting gauge, you can put a precisely angled

bevel into a piece of metal much more easily than

doing it by hand.

The actual process of sharpening a tool depends

a little on the type of tool that you’re sharpening, so

look up the proper process for working with your tool

before starting.

One key thing in sharpening all tools on a bench

grinder is not to overheat the metal. Most cutting

tools are made of steel that’s hardened by heat

treatment. If you heat it up too much, this can undo

the heat treatment and leave you with softer metal.

In order to keep the temperature down, only apply

light pressure to the metal being ground, and dip

occasionally in water to keep it cool.

Right

Most bench grinders

have two wheels, as

this creates a more

balanced drive system

Ben Everard

@ben_everard

Ben loves cutting stuff,

any stuff. There’s no

longer a shelf to store

these tools on (it’s now

two shelves), and the

door’s in danger.

Maker’s Toolbox:

Bench grinders

E

TOOLS

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