# Tooth Count for 6 1/2 inch Circular Saw Blades

Why are 60T and 80T finishing blades not available for smaller circular saws?

Diablo makes 60T blades starting at 8-1/2 and DeWalt has 60T blades starting at 10in. Is this because the smaller blade's circumferential rotation speed is not fast enough to make the fine-tooth blade effective? Or are table saws the best tool for the finer-tooth blades? Was hoping to get a cordless circular saw that could be used for precision cuts.

### Teeth-per-inch based on @Ecnerwal's answer:

http://codepen.io/anon/pen/BpqqPE?editors=0010

Geometry. It ain't the number of teeth, it's how close together the teeth are.

an 8.5" blade is 26.7 inches long at the edge.

a 6.5" blade is only 20.4 inches long at the edge.

• True, but why not offer a 60T 6.5" blade would that match 80T 8.5" teeth-per-inch? Feb 9, 2017 at 18:39
• @Chris - Those ratios don't make sense. Circumference isn't an even relationship with diameter. Feb 9, 2017 at 19:56
• @DMoore It's a trigonometric relationship: 6.5" 40T blade TPI = 40 / 6.5 / π Feb 9, 2017 at 20:29

The 'T' spec of the blade is just the number of teeth it has, and doesn't directly specify how fine the pitch is.
A larger blade with the same 'T' value will have a finer pitch than a smaller blade.

A 45T or 46T 6-1/2 blade" (if such a thing exists) would have the virtually same tooth pitch as a 60T 8-1/2" blade.
I see 40T and 48T 6-1/2" blades advertised here (just an example, not a recommendation).

The 80T 8-1/2" equivalent for a 6-1/2" blade would be 61T, but there closest options I see at the same source are 52T or 90T.

## Feeds and speeds

If you've ever done metalwork, you know that delicious sweet spot where you're running fast, chips are long and clean, and when you reach the end of the cut, the cutterhead is barely warm.

We play more casual with wood, but feeds and speeds matter there too. And that's what it's all about.

What you should be looking at is blade rate: number of blades x RPM. And also feed rate: since you don't have motorized feeds on woodwork, you kinda have to wing that one.