Short answer: The rim decides what a diamond blade is good at. A continuous rim gives the cleanest edge on tile and glass. A turbo rim cuts fastest and handles metal and general work. A segmented rim runs coolest and is built for concrete, brick and stone. Whichever you pick, it has to match your grinder in three numbers: diameter, arbor hole and maximum RPM.
What is a diamond blade, and how is it different from a cut-off wheel?
A diamond blade is a steel disc with diamond grit bonded to the rim. The diamonds do the cutting, the steel body stays the size it started. An abrasive cut-off wheel is the opposite: a block of bonded grit that wears itself away with every cut, from 4 inches down to a stub.
That one difference drives everything else. A diamond blade cuts as deep and as fast on its last job as on its first. It also handles hard, brittle materials that shred abrasive wheels: porcelain, granite, glass. The full comparison is in Diamond vs Abrasive Cutting Discs.
Which rim type do I need?
Look at the edge of the blade. It tells you what the blade was designed for.
| Rim | What it looks like | Built for | Trade-off |
|---|---|---|---|
| Continuous | One smooth, unbroken edge | Ceramic and porcelain tile, glass, mirror. Anything that chips. | Slowest of the three and runs hot when cut dry. Keep it moving or cut wet. |
| Turbo | Serrated edge, often with cooling holes in the body | Fast cutting in metal, and general work across stone and tile | Leaves a slightly rougher edge on tile than a continuous rim. |
| Segmented | Slots cut into the rim, splitting it into segments | Concrete, brick, pavers, granite, marble. Hard, abrasive material that builds heat. | The gaps chip fragile tile and glass. Wrong tool for a bathroom wall. |
The gaps in a segmented rim are not decoration. They let air through to carry heat away and clear the slurry that would otherwise pack into the cut. That is exactly what dense stone needs, and exactly what a thin porcelain tile does not.
Which blade for which material?
Each disc in our range is built around one rim type and one material. All of them are 4 inch (100 mm) outer diameter with a 5/8 inch (16 mm) arbor, rated to 12,225 RPM.
| Material | Rim | Disc |
|---|---|---|
| Glass and mirror | Continuous | Indestructible Disc, the glass cutting disc |
| Steel, aluminum, copper, brass | Turbo | Indestructible Disc 2.0, the metal cutting disc |
| Concrete, brick, granite, marble | Segmented | Indestructible Disc 3.0, the concrete and stone cutting disc |
| Ceramic and porcelain tile | Turbo, fine | Indestructible Disc 4.0, the tile cutting disc |
| Hardwood and softwood | Not a cutting blade: a toothed shaping face | Indestructible Carving Disc, the wood carving disc |
Every cutting disc in that table also handles the other materials once its main job is done. The rim just decides where it is fastest and cleanest.
What size and arbor does my grinder take?
Three numbers are printed on every blade and every grinder, and all three have to agree.
- Outer diameter. 4 inch and 4.5 inch (100 mm and 115 mm) are the common small sizes. The blade has to fit under your guard.
- Arbor hole. The hole in the middle. 5/8 inch and 7/8 inch (16 mm and 22 mm) are the usual sizes on small grinders. Our discs use 5/8 inch.
- Maximum RPM. The blade's rating must be higher than your grinder's speed. Ours are rated to 12,225 RPM. Most 4 and 4.5 inch grinders run around 10,000 to 11,000 RPM.
Not sure what your tool takes? Will This Disc Fit My Grinder? shows you where to look in ten seconds.
Wet or dry?
Small diamond blades are built to cut dry in short bursts. Give the blade a few seconds running free between cuts and it stays cool enough.
Wet cutting is still better on tile and stone: it kills the dust, cools the rim and extends blade life. It also means water near a power tool, so use a GFCI outlet and keep the motor dry. Never dry cut concrete or stone indoors without extraction. The dust is crystalline silica, and the damage it does is permanent.
How long does a diamond blade last?
Until the grit is worn off the rim, not until the blade has disappeared. Heat is what shortens that life: too much pressure or a dwell in one spot softens the bond and drops diamonds early.
If a blade stops cutting but looks fine, it has usually glazed over. Cut into a concrete block or a dressing stone to expose fresh grit, then cut cooler than before. More on that in How Long Should an Angle Grinder Disc Last?
How do I read the label?
A typical label reads something like 4 x .040 x 5/8: diameter, thickness, arbor. Next to it sits the maximum RPM and the material symbols. A thin blade cuts faster with less heat. A thicker blade tolerates more side pressure but cuts slower. Our discs are 0.04 inch thick, which is on the thin side for a clean, fast cut.
The short version
Continuous rim for tile and glass, turbo rim for metal and speed, segmented rim for concrete and stone. Check diameter, arbor and RPM before you buy, cut wet where you can, and dress the rim when it glazes.
See the range: Cutting Discs for Angle Grinders
