Carbide vs Diamond vs CBN Burs: Choosing NAKANISHI Rotary Bits by Material
Carbide burs, diamond burs, CBN burs, mounted stones and rubber polishers all fit the same rotary tool, but they do very different jobs. Picking the wrong one wastes the bit or the part. This guide explains what each type is for, using NAKANISHI's range as the example, so you can match the bit to your material.
Quick picks by material
Cutting and deburring
NAKANISHI 28111
12 titanium-coated carbide cutters, double cut, 3 mm shank, 3–6.3 mm heads.
View NAKANISHI 28111
Glass, ceramics, carbide
NAKANISHI 15305
12 electroplated diamond burs, 3 mm shank.
View NAKANISHI 15305
Steel grinding
NAKANISHI 43405
18 mounted grinding points (11 WA, 7 PA), 3 mm shank.
View NAKANISHI 43405
Smoothing and polishing
NAKANISHI 47901
12 rubber and silicone polishers in three types, 2.34 mm shank.
View NAKANISHI 47901
Assorted diamond shapes
NAKANISHI 12841
18 diamond burs in a dedicated case, 3 mm shank.
View NAKANISHI 12841- Removing metal, chamfering, deburring: carbide burs (cutters).
- Hard, brittle materials such as cemented carbide, ceramics, glass, stone and silicon: diamond burs.
- Hardened steels such as tool steels and high-speed steel: CBN burs.
- Grinding steel with a stone: mounted grinding points.
- Smoothing and polishing after grinding: rubber or silicone polishers.
- Before you buy: check the shank size (3 mm or 2.34 mm) against your collet, and never exceed the bit's maximum speed.
The five types at a glance
| Type | Best for | How it removes material | Examples in our store |
|---|---|---|---|
| Carbide bur (cutter) | Heavy cutting to finishing, chamfering, deburring | Cutting edges on a solid carbide head | 28111, 24008 |
| Diamond bur | Hard, brittle materials: cemented carbide, ceramics, glass, stone, silicon | Diamond grains electroplated on the head | 15305, 15311 |
| CBN bur | Hardened steels (SKH, SKD, SKS, SCM) and heat-resistant alloys | CBN grains electroplated on the head | 15312 |
| Mounted grinding point | Grinding steel; WA points suit hardened carbon steel and tool steel | Bonded abrasive stone | 43405 |
| Rubber / silicone polisher | Smoothing and polishing | Abrasive grain held in rubber or silicone | 47901, 46601 |
Material guidance comes from the sources listed at the end. Specifications come from each product page.
Carbide burs: for cutting and deburring
Carbide burs have cutting edges, so they remove material quickly. NAKANISHI describes its 3 mm-shank carbide cutters as usable for everything from heavy cutting to finish cutting, chamfering and deburring, and offers them in single-cut or double-cut patterns to suit the work.
- Single cut leaves a better surface finish, according to NAKANISHI's carbide cutter catalog.
- Titanium-coated cutters are made for longer tool life and less clogging, according to the same catalog. The 28111 set has 12 titanium-coated, double-cut cutters.
- Small heads for fine work: the 24008 is a 1.4 mm ball, single cut, solid carbide, rated up to 80,000 rpm.
Diamond burs: for hard, brittle materials
Diamond burs grind with abrasive grains rather than cutting edges. NAKANISHI's catalog text for its electroplated diamond burs says they suit hard, brittle materials such as cemented carbide, ceramics, glass, stone and silicon.
- 15305: 12 assorted diamond burs, 3 mm shank
- 15311: 10 assorted diamond burs, 3 mm shank
- 12841: 18 craft diamond burs in a case, 3 mm shank
CBN burs: for hardened steel
CBN (cubic boron nitride) is an abrasive suited to ferrous metals, according to TRUSCO's description of its CBN bars. NAKANISHI's catalog text for its small-diameter diamond and CBN bars lists hardened steels (SKH, SKD, SKS and SCM grades) and heat-resistant alloys. For tool steel and other hardened steel parts, CBN is the usual choice.
- 15312: 10 assorted electroplated CBN burs, 3 mm shank
Mounted grinding points: stones on a shank
Mounted points are small grinding stones. The letters show the abrasive. WA (white alumina) is hard with slightly lower toughness, which suits hardened carbon steel and tool steel with little clogging, according to TRUSCO's description of WA mounted points.
The 43405 set has 11 WA and 7 PA points on 3 mm shanks. We also stock NAKANISHI points in packs of 10 and long-shaft versions in the mounted grinding points collection.
View NAKANISHI 43405Rubber and silicone polishers: for the final finish
These hold abrasive grain in rubber or silicone, so they are softer than stones. The grit tells you how fine the finish will be. Two examples from our store:
- 46601 Power Polisher: WA #80, medium hardness, 10 mm ball, 3 mm shank, max 30,000 rpm
- 46311 Silicone Polisher: GC #500, soft, 5 mm bullet, 2.34 mm shank, max 20,000 rpm
Not sure which to start with? The 47901 assortment has four each of Green Polisher, High-Shine Polisher and Silicone Polisher.
Browse rubber and silicone polishersCheck these two things before you buy
1. Shank size
NAKANISHI bits in our store use a 3 mm or a 2.34 mm shank, shown on every product page. Use a collet that matches the shank exactly. Note that 3 mm is not the same as 1/8" (3.175 mm). We stock NAKANISHI collets, including CHA-3.0 and CHA-3.175, in the parts and attachments collection.
2. Maximum speed
Every bit has a maximum operating speed. It varies a lot by type: in the examples above, from 20,000 rpm (46311 silicone polisher) to 80,000 rpm (24008 carbide cutter). Running a bit faster than its rating is unsafe. Check the product page and set your grinder below it.
FAQ
Carbide bur or diamond bur for steel?
For ordinary steel, a carbide bur or a WA mounted point. For hardened steel, a CBN bur. Diamond burs are for hard, brittle materials such as glass, ceramics, stone and cemented carbide.
What is the difference between single cut and double cut?
NAKANISHI offers both and recommends choosing by the work. Its catalog says single cut gives a better surface finish.
Do NAKANISHI bits fit other rotary tools?
The bit fits any tool whose collet matches the shank size, 3 mm or 2.34 mm. Always stay below the bit's maximum speed.
Related
- All NAKANISHI tools (micro grinders, spindles and consumables)
- NAKANISHI micro grinders and spindles
- NAKANISHI rotary brushes
- Japanese hand tools guide
Shipped directly from Japan
We ship genuine NAKANISHI tools from Osaka with tracking (Japan Post, FedEx or DHL). For US orders, import duties are included in the price.
Browse NAKANISHI toolsSources
- MISUMI: NAKANISHI carbide cutters, 3 mm shank: heavy to finish cutting, chamfering, deburring; single or double cut
- NAKANISHI carbide cutters catalog (DirectIndustry): single cut finish, titanium coating
- MISUMI: NAKANISHI electroplated diamond burs: hard, brittle materials
- MISUMI: NAKANISHI small-diameter electroplated diamond and CBN bars: hardened steels and heat-resistant alloys; hard, brittle materials
- MISUMI: Minitor carbide cutters: carbide cutters for general steel, tool steel, stainless steel, aluminum and copper
- MISUMI: TRUSCO CBN bars: CBN for ferrous metals
- MISUMI: TRUSCO WA mounted points: WA abrasive for hardened carbon steel, general steel and tool steel
- Product specifications (shank, head size, grit, hardness, maximum speed, set contents): NAKANISHI catalog data via Orange Book (TRUSCO), shown on each linked product page
