What Grit Sizes for Abrasive Mounted Points in Metalwork?

Choosing the wrong grit size for abrasive mounted points can lead to scorched metal, uneven surfaces, or endless grinding sessions that waste time and tools. In metalwork, mounted points are essential for die grinders and rotary tools, but their effectiveness hinges on matching grit to the task—whether rough stock removal or mirror polishing.

This guide breaks down grit sizes from coarse to fine, explains their applications in metalwork, and helps intermediate users select the right ones for steel, aluminum, and more. You'll learn the grit scale, task-based recommendations, and pro tips to avoid common pitfalls. Expect to gain confidence in under 20 minutes of reading.

No hands-on work required—just solid knowledge to upgrade your next project.

▸What You'll Need

• •Basic knowledge of die grinders or rotary tools
• •Safety gear (gloves, goggles, respirator)
• •Sample abrasive mounted points in various grits (optional for testing)
• •Access to a rotary tool for hands-on verification

Estimated Time: 15-20 minutes Difficulty: intermediate

▸Step-by-Step Instructions

Step 1: Understand What Abrasive Mounted Points Are

Abrasive mounted points are small, shaped grinding tools with a mandrel shank (usually 1/8" or 1/4") that fit into die grinders, Dremels, or air tools. Made from aluminum oxide (AO) or silicon carbide (SC), they're used for grinding, deburring, and shaping metal.

Why grit matters here: The abrasive grains determine cut speed and finish quality. Think of grit like sandpaper—coarser tears metal away fast but leaves scratches; finer smooths them out.

Expect points to last 5-30 minutes per use, depending on grit and pressure.

💡 Tips:

• •Start with AO for ferrous metals like steel; SC for non-ferrous like aluminum.

⚠️ Warnings:

• •Never use on wood or plastic—can shatter.

Step 2: Learn the Grit Size Scale

Grit size is measured by mesh number: lower numbers = coarser (bigger grains, aggressive cut); higher numbers = finer (smaller grains, smoother finish). CAMI (Coated Abrasive Manufacturers Institute) scale is standard.

Key ranges:

• •Extra Coarse: 16-24 grit (rapid removal)
• •Coarse: 30-60 grit
• •Medium: 80-120 grit
• •Fine: 180-240 grit
• •Extra Fine: 320+ (polishing)

For metalwork, most points range 24-180 grit. Analogy: Coarse like a chainsaw for logs; fine like a razor for shaving.

💡 Tips:

• •Memorize 36/60/120 as your 'workhorse' trio.

Step 3: Match Coarse Grits (24-60) to Heavy Removal

Use 24-36 grit for weld removal, heavy stock stripping on steel or iron. 46-60 grit for initial shaping on harder metals.

Why it works: Large grains fracture and renew quickly, ejecting chips fast. Expect high heat—cool with light pressure.

Perfect for gates, sprues, or roughing out contours; leaves visible scratches to refine later.

💡 Tips:

• •Pair with high RPM (20,000-30,000) for best chip flow.

⚠️ Warnings:

• •Avoid on thin metal—can gouge or warp.

Step 4: Use Medium Grits (80-120) for Blending

80-100 grit smooths coarse scratches; 120 grit preps for finishing. Ideal for blending welds on stainless or mild steel.

Pro insight: This range balances speed and control—removes material 3x slower than coarse but 5x smoother.

Transition here after coarse work; you'll see scratches fade into a satin finish.

💡 Tips:

• •Tilt tool 15-30 degrees for even wear.

Step 5: Select Fine Grits (180+) for Finishing

180-220 grit for pre-polish on chrome or aluminum; 320+ for final buffing.

When to choose: After medium grit, for visible surfaces or tight tolerances. Grains polish rather than cut, minimizing heat.

Result: Near-mirror finish ready for plating or painting.

💡 Tips:

• •Use low pressure and speed (10,000-15,000 RPM) to avoid burning.

⚠️ Warnings:

• •Fines load up fast—dress with a wire brush.

Step 6: Factor in Metal Type and Tool Speed

Softer metals (aluminum) need coarser/fresher grits to avoid clogging. Hard steels: finer for control.

RPM guide: Match point diameter—smaller points faster speeds. Pressure: Light for fine, firm for coarse.

Test on scrap: If glazing (shiny dull spots), go coarser or increase speed.

💡 Tips:

• •Aluminum: SC grit; Steel: AO grit.

Step 7: Test and Progress Grits Logically

Workflow: Start 2x coarser than needed, step down (e.g., 36 > 80 > 180). Each pass removes prior scratches.

Inspect frequently—magnify 10x if possible. This ensures efficiency and pro results.

💡 Tips:

• •Mark grits on tools with tape for quick ID.

⚠️ Warnings:

• •Skipping steps leaves 'ghost' scratches.

▸Pro Tips

• •Buy sets with multiple grits for versatility—saves 30% vs. singles.
• •Clean points with a brass brush every 2 minutes to extend life 2x.
• •Use cutting oil on stainless to cut heat 50%.
• •Store in divided cases to prevent contamination.
• •Mark RPM limits on each point—over-speed dulls fast.
• •Progress grit numbers by factor of 2 (36 to 80 to 180).
• •For contours, use ball-shaped points in coarse.

▸Common Mistakes to Avoid

• •Using one grit for all tasks—leads to poor finish or glazing; always progress.
• •High pressure on fine grits—burns metal; use feather-light touch.
• •Wrong abrasive type (AO on aluminum)—clogs instantly; match to metal.
• •Ignoring RPM—too slow loads grit, too fast wears unevenly.
• •Not dressing loaded points—reduces life by 70%; brush regularly.

▸Troubleshooting

Problem: Point glazing or loading (shiny/dull spots)

Solution: Switch to coarser grit, increase RPM, or dress with wire brush. Use lubricant for soft metals.

Problem: Excessive heat/vibration

Solution: Reduce pressure, check balance, lower RPM. Replace if shank bent.

Problem: Uneven finish or gouges

Solution: Progress grits properly; use consistent angle and speed. Test on scrap first.

Problem: Short point life

Solution: Match grit to task; avoid side-loading. Store dry.

S SATC 20Pcs 1/4" Shank Mounted Points Set (36-120 Grit Mix)

Assorted coarse-to-medium grits perfect for metalwork progression; aluminum oxide for steel durability.

Best for: Weld cleanup and blending on daily projects.

Price Range: $16.99

AUSTOR 132Pcs Abrasive Mounted Points Set (24-220 Grit)

Huge variety covers all metalwork needs; great value for intermediates experimenting.

Best for: Full workflow from roughing to polishing on aluminum or steel.

Price Range: $16.99

Forney 60162 Mounted Stone Point Set, 20-Piece (80 Grit Focus)

Reliable medium grit for blending; trusted brand with consistent shape retention.

Best for: Smoothing welds on automotive or fabrication work.

Price Range: $14.99

Pferd 65113 POLIFLAME Mounted Point A60 (60 Grit)

Premium single coarse grit for heavy-duty steel; vitrified bond resists heat.

Best for: High-volume stock removal without frequent changes.

Price Range: $10-15

Weiler 804-110010 Tiger AO Mounted Point (36 Grit)

Aggressive coarse for tough metals; long-lasting for pros.

Best for: Gate removal on cast iron or tool steel.

Price Range: $3.99 each