Circular Saw Arbors & Blades
Tool Drives & Bit Shanks · 7 specs
Direct Answer
Circular saw blade arbors (center mounting bore holes) are standardized into 5/8-inch (15.88 mm with diamond knockout for worm-drive saws), 1-inch (25.4 mm for table/miter saws), 20 mm, and 30 mm (European standard), paired with Alternate Top Bevel (ATB) or Triple Chip Grind (TCG) tooth geometries.
Source: ANSI B7.1 / EN 847-1 Safety requirements for woodworking tools / Circular saw blade standards · Last reviewed Aug 28, 2026
Specs
| Governing Standards | ANSI B7.1 / EN 847-1 / ISO 293 / OSHA 1926.304 |
| 7-1/4" Circular Saw Arbor | 5/8" (15.875 mm) round bore with diamond knockout insert (worm-drive framing saws) |
| 10" / 12" Table & Miter Saw Arbor | 5/8" (10-inch North American) or 1.00" (25.4 mm 12-inch heavy-duty saws) |
| European Standard Arbor (EN 847) | 20.0 mm (cordless/plunge saws) and 30.0 mm (stationary table & panel saws) |
| Standard Kerf Thickness | Full Kerf: 1/8" (3.18 mm) | Thin Kerf: 3/32" (2.38 mm for cordless power savings) |
| ATB Tooth Grind | Alternate Top Bevel (15°–20° bevel) | Clean cross-cutting across wood grain |
| TCG Tooth Grind | Triple Chip Grind (trapezoidal tooth + flat raker) | Melamine, laminates, non-ferrous aluminum |
Circular Saw Blade Diameter & Arbor Hole Size Matrix
| Saw Blade Diameter | North American Standard Arbor | European Standard Arbor | Tooth Count (TPI) Range | Primary Cutting Purpose |
|---|---|---|---|---|
| 6-1/2" (165 mm) | 5/8" (15.88 mm) | 20.0 mm | 18T (Rip) to 48T (Fine) | Cordless circular framing saws, track plunge saws |
| 7-1/4" (184 mm) | 5/8" + Diamond Knockout | 30.0 mm | 24T (Framing) to 60T (Finish) | Sidewinder & Worm-Drive construction framing saws |
| 8-1/2" (216 mm) | 5/8" (15.88 mm) | 30.0 mm | 24T to 60T | Compact sliding compound miter saws |
| 10" (254 mm) | 5/8" (15.875 mm) | 30.0 mm | 24T (Rip), 40T (Combo), 80T (Fine) | Standard Cabinet Table Saws & Miter Saws |
| 12" (305 mm) | 1.00" (25.40 mm) | 30.0 mm | 40T (General) to 100T (Ultra-Fine) | Heavy dual-bevel sliding miter saws |
| 14" (350 mm) | 1.00" (25.40 mm) | 25.4 mm / 30.0 mm | 60T to 120T | Cold metal cutoff saws, industrial chop saws |
Diamond Knockout Mechanics in Worm-Drive Saws
In high-torque worm-drive framing saws (Skilsaw style), round arbor collars can slip during sudden lumber binding. The blade's pre-stamped diamond center can be punched out with a hammer, locking the blade directly onto the saw's diamond-shaped drive spindle to transfer 100% rotational torque without slipping.