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The Brunsfield Center/Manufacturing Technologies/Grinders

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This page contains information about the various types of grinders in Brunsfield.

What is Grinding?

Grinding is a material removal process that uses a rotating abrasive tool — typically a grinding wheel or disc — to wear away unwanted material. Unlike cutting, grinding removes small chips from a workpiece using many tiny abrasive particles.

It is used to:

  • Smooth rough surfaces
  • Remove welds or mill scale
  • Shape or bevel edges
  • Prepare joints before welding
  • Clean up welds after welding

Grinding is a fast, precise, and versatile method for preparing or finishing metal surfaces.

Required PPE

  • Safety glasses AND face shield
  • Welding gloves or work gloves
  • Welding jacket or flame-resistant clothing
  • Long pants, non-synthetic (e.g., cotton or denim)
  • Steel-toe boots
  • Hearing protection

Handheld grinders

Types of Grinding Wheels and Discs

1. Cutting Wheels (Cut-Off Discs)

  • Thin (~1/16") and sharp
  • Designed for slicing straight through metal
  • Never use side pressure — they're brittle and can shatter
  • Commonly used to cut tubing, sheet metal, or bolts

2. Grinding Wheels

  • Thicker (~1/4") and more robust
  • Used to grind down welds, remove rust or scale, or shape metal
  • Designed for face grinding with moderate pressure
  • Can remove a large amount of material quickly

3. Flap Discs

  • Made of overlapping abrasive flaps on a disc
  • Excellent for smoothing, blending, or deburring
  • Gentler than grinding wheels, but still effective
  • Useful for finishing work or shaping weld beads before paint or inspection

Hazards

  • Flying sparks, hot metal fragments
  • Wheel shattering or disintegration
  • Fire risk from flammable materials
  • Noise exposure and vibration
  • Entanglement of clothing, hair, or jewelry

Pre-Operation Checklist

  1. Inspect tool and accessories:
    1. Ensure the grinder is in good working order (cords, switches, guards)
    2. Check for cracks or damage on the wheel/disc
    3. Position the guard shield yourself from sparks and debris.
  2. Wheel Selection:
    1. Cutting wheel – thin abrasive disc, used for slicing through metal
    2. Grinding wheel – thicker, used for surface grinding or weld removal
    3. Flap disc – layered sanding disc, used for smoothing or blending
  3. Secure the Workpiece:
    1. Clamp or hold material firmly
    2. Keep flammables clear of the grinding area
  4. Tool Setup:
    1. Use guard appropriate to the wheel type.
    2. Mount wheel securely, tighten with correct tool.

Operating Procedure

  1. Start-up:
    1. Stand to the side of the wheel on start-up
    2. Let the grinder reach full speed before contacting work
  2. During Use:
    1. Maintain a firm grip with both hands
    2. Use the correct angle:
    3. ~90° for cutting
    4. ~15–30° for grinding or flap discs
    5. Keep sparks directed away from yourself and others
    6. Avoid side pressure on cutting wheels
  3. Shut Down:
    1. Let the disc come to a complete stop before setting it down
    2. Unplug when changing accessories or leaving the station

Post-Use

  • Clean the area of metal dust and debris
  • Store the grinder and wheels in their respective drawers in the grinding cabinet
  • Report any damage to shop staff immediately

🚫Prohibited Actions🚫

  • Do NOT grind outside the welding bay
  • Do NOT use a wheel that has been dropped or shows damage
  • Do NOT remove guards
  • Do NOT wear loose clothing, jewelry, or untied hair

Die Grinders

What is a Die Grinder?

A die grinder is a handheld rotary tool used for precision grinding, sanding, polishing, deburring, and cutting. It spins small attachments — typically carbide burrs, grinding stones, flap wheels, or abrasive drums — at very high speeds (often 20,000–30,000 RPM).

Die grinders come in electric and pneumatic (air-powered) versions. Pneumatic versions are most common in fabrication shops due to their lightweight and durability.

Common Uses in Metalworking

  • Cleaning up welds in tight spots
  • Deburring sharp edges or holes
  • Grinding in corners or around complex geometry
  • Surface prep in small areas
  • Smoothing internal bores or notches

Die grinders are especially useful where angle grinders are too large or aggressive.

Hazards

  • High-speed rotation of small tools
  • Flying chips, sparks, or wire fragments
  • Loose bits or mandrels at high RPM
  • Air hose whip  
  • Vibration and noise

Pre-Operation Checklist

  1. Inspect the Die Grinder:
    1. Check tool body, trigger, and air hose for damage
    2. Ensure the guard (if applicable) is installed and secure
    3. Check collet tightness and condition
  2. Inspect the Bit/Attachment:
    1. Only use bits rated for high RPMs
    2. Do not use damaged, bent, or worn tools
    3. Ensure the bit is inserted to full depth and securely tightened
  3. Setup:
    1. Ensure Air hose is secured and in good condition.
    2. Clamp the workpiece or ensure it is fully secured
    3. Keep bystanders clear and flammable materials away

Operating Procedure

  1. Start-Up:
    1. Hold the tool firmly with two hands (if possible)
    2. Let it reach full speed before contacting the material
  2. During Use:
    1. Use light pressure — let the tool do the work
    2. Keep a stable stance, and avoid awkward or strained positions
    3. Maintain control if tool catches or kicks
    4. Keep cords and air hoses away from the spinning bit
  3. Shut Down:
    1. Release the trigger and wait for the tool to fully stop
    2. Disconnect air/power before changing bits or leaving the tool unattended

Post-Use

  • Clean up metal debris and dust
  • Store attachments in designated bins
  • Hang hoses and cords properly
  • Report damage or worn tools to shop staff

🚫Prohibited Actions🚫

  • Do NOT use attachments not rated for high RPMs
  • Do NOT use die grinders outside of the welding bay
  • Do NOT operate without both hands on tool when required
  • Do NOT grind in a way that directs sparks at people, hoses, or cables
  • Do NOT modify bits or use makeshift attachments

Pedestal Grinder

The pedestal grinder is a pair of large grinding wheels mounted at hip height in the welding bay in Brunsfield. One wheel is more abrasive than the other, but both are used to remove large amounts of material from metal workpieces.

Pre-Use Safety Checklist

  • Tool rests set within 1/8” of wheel
  • Spark guards in position
  • Wheel not cracked or damaged (ring test if unsure)
  • Shield and work light functional
  • Area is clean and dry

Operating Instructions

  1. Start-Up
    1. Stand to side of wheels during start-up.
    2. Let wheels come up to full speed (~15 seconds).
    3. Never grind on the side of the wheel.
  2. Grinding
    1. Hold workpiece firmly with both hands.
    2. Maintain a firm grip and light pressure.
    3. Use cooling breaks to avoid overheating metal.
    4. Use the full face of the wheel to prevent wear grooves.
  3. Tool Rest Use
    1. Support work on the tool rest, not freehand.
    2. Keep rest adjusted close to wheel to prevent jamming.

Post-Use Procedure

  • Turn off grinder, wait for full stop.
  • Clean surrounding area with brush or vacuum.
  • Log any damage or unusual behavior.
  • Never leave machine running unattended.

🚫Prohibited Actions🚫

  • DO NOT wear gloves of any kind while using the pedestal grinder.
  • NO ALUMINUM is to be used on the grinder. The soft metal will clog the wheel and ruin it.
  • Keep the workpiece firmly against the support at all times.
  • Use ear protections, this machine is very loud.
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