The three geometry factors that matter most
Saw blade geometry is a complex topic, but three factors account for 90% of cut quality differences:
- Hook angle: How aggressively the tooth reaches into the wood. Positive = aggressive (rips fast), negative = passive (clean cuts in sheet goods).
- Grind type: The shape of the tooth's cutting edge. ATB (alternating top bevel) for crosscuts, FTG for rips, TCG for tough materials.
- Tooth count: Determines how many cuts per revolution — more teeth = smoother, fewer = faster.
Hook angle in depth
Hook angle is measured from a line tangent to the saw's circumference at the tooth's tip. Most blades are between -5° and +20°.
- -5° to 0° (negative or zero): Used on sliding miter saws and for cutting sheet goods. Prevents the blade from "climbing" the workpiece.
- 0° to 10° (low positive): Standard for table saws and most crosscutting. Balanced performance.
- 10° to 20° (high positive): Aggressive ripping on table saws. Fast feed but more tear-out. Common on dedicated rip blades.
- 20°+ (very aggressive): Specialty blades for heavy production ripping. High kickback risk — requires experienced operator.
Grind geometry explained
The shape of the tooth's cutting edge determines how it slices wood:
- FTG (Flat Top Grind): The tooth top is flat, perpendicular to the blade. Best for ripping — slices wood like a chisel.
- ATB (Alternating Top Bevel): Teeth alternate between left- and right-leaning bevels. Slices across grain cleanly. The standard for crosscut blades.
- HiATB (High ATB): Steeper bevel angles (20-30°). Even cleaner cuts. Used for finish blades cutting plywood and veneer.
- TCG (Triple Chip Grind): One tooth rakes, the next is flat-topped. Designed for hard materials — plywood with metal fasteners, dense hardwoods, non-ferrous metals.
Plate thickness and kerf
The blade's plate (the body of the saw) is slightly thinner than the tooth tips, which are "set" (bent outward) to give the cut a slightly wider path than the plate. This is called the kerf.
- Full kerf: Plate is 0.083" thick, tooth set gives 0.125" kerf. Rigid, accurate. Best for high-powered saws.
- Thin kerf: Plate is 0.063" thick, kerf around 0.094". Easier on low-powered saws. Slight loss of rigidity.
- Ultra-thin kerf: Plate 0.042" thick, kerf 0.060". For track saws and very low-powered saws. Least rigid.
Tooth pitch and gullets
Tooth pitch = the distance from one tooth tip to the next. Smaller pitch = more teeth per inch of circumference. Gullets are the curved valleys between teeth — they carry away the chips. The relationship:
- Deep gullets = high chip capacity = aggressive cuts = faster feed
- Shallow gullets = lower chip capacity = smoother cuts = slower feed
For most crosscutting and finishing work, shallow gullets are correct. For production ripping, deep gullets handle the chip volume.
Why "one blade for everything" rarely works
Combo blades exist (Freud Diablo, Forrest Woodworker II) that compromise between ripping and crosscutting. They're a reasonable choice for hobbyists who don't want to swap blades constantly. But a dedicated rip blade + dedicated crosscut blade will always out-perform a combo blade in their respective tasks.
Specialty blade geometries
- Dado set: Two outside blades plus chipper blades. Adjustable width from 1/4" to 13/16". Common tooth counts: 24.
- Scoring blade: Small-diameter blade mounted in front of main blade. Pre-cuts the surface to prevent tear-out on plywood.
- Concave / flat grind: Specialty blades for joinery (raised panel bits).
- Conical scoring: Adjustable-angle scoring blade for clean cuts at angles.
Frequently asked questions
Why does my saw blade leave scoring marks on the cut edge?
The blade has too few teeth for the cut. Each tooth is taking too big a "bite." Use a higher tooth count for finer cuts.
What's the difference between a $20 and a $200 blade?
Carbide grade, plate quality, tooth geometry precision, and balance. A premium blade lasts 5-10× longer than a budget blade, often at a lower cost-per-cut over its life.
Can I resharpen carbide?
Yes, by a professional service. The cost is $15-30. Budget blades are usually cheaper to replace than sharpen.