Soft bond for hard stone
Hard, dense stone such as granite needs a soft bond so the matrix wears back and keeps exposing fresh diamond. A hard “universal masonry” bond on granite polishes over and stops cutting.
01
25–35 m/s
Wet cut line speed
−20–30 % rpm
Dry cutting
5–7 L/min
Water flow
+20 % life
12 mm vs 10 mm segment
01 — At a glance
The three things that matter most
Natural and engineered stone is dense, abrasive and unforgiving. Almost every “bad blade” complaint traces back to three things: the wrong bond for the stone, a peripheral speed that is too high, and not enough water.
Wet cutting is the default
Water cools the bond, flushes abrasive slurry and suppresses silica dust. On a bridge saw or CNC it is effectively mandatory — and it can add 30–50 % to blade life.
Think line speed, not rpm
Blade diameter changes everything. Use peripheral speed: m/s = π × D(m) × rpm ÷ 60. A 400 mm blade at 3,000 rpm is 63 m/s — nowhere near a safe or efficient range for granite.
02 — Tool matching
Match the tool to the material
Pick the row for your material. If two rows look similar, start with the slower option — it is almost always the safer and cheaper mistake.
| Material | Recommended blade | Bond | Line speed | Cooling |
|---|---|---|---|---|
| Hard granite (India Black, Shanxi Black) | Segmented or laser-welded | Soft | 25–30 m/s | Wet, 5–7 L/min |
| Medium granite (typical countertops) | Segmented / turbo | Soft–medium | 30–35 m/s | Wet |
| Marble, limestone, onyx | Continuous rim | Medium | 30–40 m/s | Wet |
| Engineered quartz | Turbo / continuous, fine grit | Medium–hard | 25–30 m/s | Wet (mandatory) |
| Porcelain slab / sintered stone | Continuous rim, fine grit | Hard | 20–25 m/s | Wet |
| Concrete, brick, block | Segmented | Hard | 30–40 m/s | Wet or dry * |
* Dry cutting concrete is only acceptable with a dust shroud and HEPA extraction plus a P2/N95 respirator — see Construction & Concrete.
03 — Step by step
Six steps to a chip-free, blade-friendly cut
In order. Skipping a step usually costs more time than it saves.
01
Match the blade to the stone, not to the saw
Read the stone first. Dense hard granite wants a soft bond and 25–30 m/s. Soft marble or limestone wants a medium bond and can run faster. Engineered quartz behaves like a hard granite but is more brittle — continuous rim, fine grit, always wet.
02
Set the speed from the table, not from feel
Dial the machine to the rpm that gives you your target line speed for that blade diameter. Never leave the saw on one setting for every blade size — a 600 mm blade at 1,500 rpm is 47 m/s, far too fast for granite.
03
Break in a new blade
Run a new blade 10–15 % slower for the first 10–15 cuts. This seats the diamonds in the bond. Cranking a fresh blade straight to full speed knocks diamonds loose before the metal has worn enough to hold them.
04
Feed so the blade cuts, not rubs
Start at about 70 % of the maximum feed and increase until you see a steady, fine slurry and a straight kerf. Rubbing at too low a feed polishes the diamonds flat — the classic glazing failure that makes a blade feel blunt.
05
Keep water on both faces of the blade
Aim for 5–7 L/min with the nozzles wetting both sides of the kerf. If the blade starts cutting slowly or smoking even though speed and feed are correct, check the water first — it is almost always the cause.
06
Take passes on thick slabs
On 20 mm and thicker material, cut in 3–5 mm passes. A deep cut increases the contact area, raises heat and loads the core. Shallow passes let the blade clear and the slurry carry the swarf away.
04 — Feeds & speeds
Numbers to start from
Use these as a starting point and adjust to what the cut is telling you. Start slow and work up.
| Blade Ø | Max rated rpm | Granite 25–35 m/s | Marble 30–40 m/s | Typical machine |
|---|---|---|---|---|
| 105 mm (4") | 13,300 | 4,547–6,366 | 5,457–7,276 | Angle grinder |
| 125 mm (5") | 12,200 | 3,820–5,348 | 4,584–6,112 | Angle grinder |
| 180 mm (7") | 8,500 | 2,653–3,714 | 3,183–4,244 | Angle grinder |
| 230 mm (9") | 6,600 | 2,076–2,906 | 2,491–3,321 | Angle grinder |
| 300 mm (12") | 3,200 | 1,592–2,228 | 1,910–2,546 | Masonry / tile saw |
| 350 mm (14") | 2,800 | 1,364–1,910 | 1,637–2,183 | Bridge saw |
| 400 mm (16") | 2,500 | 1,194–1,671 | 1,432–1,910 | Bridge saw |
rpm values are computed from
rpm = 60 × v ÷ (π × D) and are the grinding range, not the safety limit. Always stay below the max rpm laser-etched on the blade.05 — Troubleshooting
If it goes wrong
The symptom is rarely the problem. Read the root-cause column before you change anything.
| Symptom | Root cause | Fix |
|---|---|---|
| Blade turns shiny, sparks, cut slows to a crawl | Bond too hard for the stone, or line speed too high — the diamonds are rubbing, not cutting | Drop speed 10–15 %, take shallower passes, dress the blade for a few seconds in a soft abrasive block, brick or cinder block |
| Edge chipping / blow-out on marble | Coarse blade, forced feed, or nothing supporting the stone at exit | Switch to a continuous rim blade, reduce feed, support the off-cut, cut 2–3 mm proud of the finish line and trim |
| Segments wear fast but the cut is clean | Running too fast for the stone, or a bond that is too soft | Reduce line speed by 10 %, verify the bond against the table, check water flow |
| Smoke or burning smell at the kerf | Water not reaching the cut | Raise flow to 5–7 L/min, re-aim the nozzles at both faces, check for a blocked line |
| Kerf wanders, cut wanders offline | Blade out of tension, worn flanges, or feed too high | Check runout and flange condition, lower the feed, keep a fresh blade for finish cuts |
| Sub-surface cracks that appear days later | Thermal shock from dry cutting brittle stone | Cut wet. If dry cutting is unavoidable, take 3 mm passes and free-spin the blade every 30 seconds to cool |
06 — Recommended tools
Blades we make for stone
Every item below is made by EXTRACUT and links straight to the product page.
Segmented Diamond Blades
Fast rough cutting in granite and concrete — open segments clear slurry quickly.
View product
Continuous Diamond Blades
Continuous rim for chip-free edges on marble, quartz and porcelain slab.
View product
Turbo Diamond Blades
Turbo rim: the all-round shop blade for stone fabricators.
View product
Laser Diamond Blades
Laser-welded segments rated for dry cutting and heavy daily production.
View product
SAMURAI Diamond Blades
Premium bond with higher diamond concentration for the hardest granites.
View product
Turbo Diamond Cup Wheel
Cup wheel for grinding, levelling and chamfering after the cut.
View product
Vacum Brazed Diamond Polishing Pads
Polishing pads to take a cut edge through to a finished surface.
View product
Electrical Plated Diamond Hole Saw Hole Cutter
Electroplated hole saw for sinks, taps and electrical cut-outs in stone.
View productNeed a specific diameter, arbor or bond? We build to drawing and laser-etch your rpm and line speed on the blade.
07 — Safety
Before you switch anything on
Short list, long consequences. These apply to every job on this page.
Silica dust is a respiratory hazard. Wet cutting suppresses it at the source. If you must cut dry, use a shroud with HEPA extraction and an N95/P2 or better respirator.
Eye and hearing protection, every cut. Wet slurry also needs cut-resistant gloves — wet slabs bite.
Clamp the stone. Never free-hand a slab on trestles; kickback on a 400 mm blade is not survivable with hands.
Let the blade reach full speed before it touches the stone. Entering a cut at partial speed invites kickback.
Check the max rpm etched on the blade. Never fit a low-speed bridge-saw blade to a high-speed grinder — segment loss and core fracture follow.
Manage the slurry. Wet cutting needs a settling pit or flocculant treatment; dry sweeping dried slurry puts silica back into the air.
08 — FAQ
Frequently asked questions
The questions our technical team answers most often.
Will any diamond blade cut granite?
Technically yes, but a generic masonry blade has a hard bond meant for concrete. On granite it will cut slowly, blow out the edge and wear out fast. Granite needs a soft-bond, high-diamond blade.
Why is my brand-new blade burning the stone?
In order of frequency: glazing (bond too hard — dress it on a soft abrasive block), excess rpm (dial back to the table), low water flow (aim for 5–7 L/min), or feed too slow (let the diamonds bite instead of polishing in place).
How long should a granite blade last?
In normal shop conditions: 4.5–7′′ grinder blades typically deliver 800–3,000 linear feet; 14–18′′ bridge-saw blades 3,000–8,000 feet. Stone hardness, water flow and rpm accuracy move that number more than blade price does.
Can I cut granite dry with an angle grinder?
Yes, for short, controlled work — a sink cut-out in a finished kitchen, for example. Take 3 mm (⅛′′) passes, free-spin the blade every 30 seconds to cool, hook up a HEPA vacuum, and wear a respirator. Continuous dry cutting can cut blade life by up to 40 %.
What is the difference between segmented, turbo and continuous rim?
Segmented cuts fastest and runs coolest but leaves a rougher edge. Turbo sits in the middle. Continuous rim is slowest but leaves the cleanest, chip-free edge — the choice for visible countertop edges.
Still not sure which tool fits the job?
Send us the material, the machine and the finish you need. Our engineers will specify the blade, bond or bit — and quote it with a sample if you want to test before you commit.