Grinding & Shaping · Grind

Angle Grinder

An angle grinder spins a cutting or grinding disc for fast, rough work on metal. It cuts stock, strips scale, and roughs in profiles before the belt grinder refines them, and it demands a guard and a face shield.

StageGrindRank#9

Specifications

At a glance
Disc size	115–180 mm (4.5–7 in)
Speed	Fixed or variable
Discs	Cut, grind, flap, wire
Power	700–2,000 W
Guard	Fitted, never removed
Use	Cutting, scale removal, roughing

Technical parameters

Typical values for this class of tool
Rated speed	8,500–11,000 RPM
Noise level	95–105 dB
Cutting disc thickness	1–3 mm
Grinding disc thickness	6 mm
Arbor size	22.2 mm
Spindle thread	M14 common
Disc max speed	Must exceed grinder RPM
Vibration	High, use anti-vibration grip

Grinding & ShapingBeginner$ typical cost

Overview

An angle grinder is a handheld power tool that spins a disc at high speed, used for cutting bar stock, rough grinding, and stripping scale. In a knife shop it is the fast, crude tool: it cuts a billet to length, knocks the mill scale off stock, and roughs in a profile before the belt grinder refines it. The disc choices are important. Thin cutting discs slice, thick grinding discs remove material, flap discs blend and finish, and wire wheels strip rust and scale. Each disc has its own speed rating, and using the wrong one is dangerous.

When choosing, match the disc diameter and the power of the grinder to the work, and always respect the RPM rating stamped on the disc. A 115 or 125 millimeter grinder is the common all-round size, while a larger 180 millimeter machine cuts deeper and heavier. Variable speed helps when using flap discs and wire wheels, which can be run too fast. The guard is not optional: it catches fragments if a disc shatters and shields your hand. Handle vibration, noise, and dust are the three things that make this tool tiring and hazardous, so grip and PPE matter.

In the workflow the angle grinder is a shortcut for rough work, not a finishing tool. It cuts stock to length, removes scale, and takes off the worst of the forge marks so the belt grinder has less to do. It is also used for cutting hardened steel where a belt would struggle, though the heat it generates must be managed. Because it removes metal aggressively and throws sparks in a wide arc, it is best used before heat treatment, on rough stock, and with the work clamped down. The belt grinder then brings the shape to final tolerance.

Where it fits

This tool belongs to the Grind stage of the build.

ForgeShapeGrindHeat TreatFinish

Safety

Before you use thisRead the manufacturer’s instructions. The points below are the hazards that come up most often with this class of tool.

Wear a full face shield, not just glasses, since a shattered cutting disc throws fragments at high speed.
Never remove the guard or over-speed a disc; check the disc RPM rating exceeds the grinder before you fit it.
Clamp the work and keep both hands on the tool, because kickback from a pinched disc can jerk the grinder out of your grip.

Using it well

Match the disc to the job: thin cut-off wheels slice, thick grinding discs hog, and flap discs blend and finish.
Let the disc cut at its own pace; forcing it overheats the steel and loads the wheel, which is what causes most kickback.
Use it before heat treatment on rough stock, and leave final shaping to the belt grinder where you control the heat.
Check the disc for cracks and its expiry date before fitting, and run a new disc for a few seconds before applying load.

Compatible steels

Steels this tool is commonly used with, and which suit its working range.

1084 1095 5160 80CrV2 O1 D2

Related processes

ProfilingGrindingFinishing

Educational reference. Forge & Anvil is an independent information resource and does not sell tools, steel or knives. Specifications and temperature ranges quoted here are typical values for the category of tool described and vary between manufacturers — always work from the documentation supplied with your own equipment. Nothing here is professional safety, legal or engineering advice.