Glossary of saw tooth styles
Dictionary of carbide teeth with pictures of tip shapes, angles, names of parts and definitions.
ATB: Alternate Top Bevel
Tips with one corner pointed on top to shear across fibers are called Alternate Top Bevel style. This means half of them cut one side, the rest on the other. Alternate bevel teeth dull faster than triple chip shapes. How neatly ATB tips cut depends on variable factors, such as spacing, whether there is a positive or negative hook angle, and the degree it is slanted. It ordinarily slants 10 or 20 degrees; not as high as the HATB kind.
Acutely pointed High Alternate Top Bevel tips are beveled 25 to 40 degrees for shearing and slicing. They have a negative hook angle. These modifications can ease the passage through extraordinarily fragile or difficult stock. HATB deflects more than a TCG shape. Save Hi-ATB for finishing details.
A tungsten carbide tooth usually has a flat face with edges on both sides. A variation of ATB gives each tip an alternate bevel on the face, so only one side has an acute edge. This type is relatively rare. All the different styles of teeth with extremely pointy shapes share a vulnerability.
Clearance
Behind a tip, the part supporting it is called its shoulder. For back clearance, the shoulder profile descends slightly. For side clearance, carbide teeth are not normally set or pried outward. Instead, they are shaped for clearance in both the vertical and horizontal planes.
In the pictures above, each tip narrows vertically from top to bottom for side radial clearance. Ample tapering scribes characteristic curved lines. The opposite of regular carbide tooth shapes, a cone is narrow at the top. The unusual conical shape is used just for superficial scoring, but not to penetrate or to sever.
In this picture looking at tangential clearance from above, tips extend outward horizontally on both sides. The profiles protrude slightly at the face and taper to the back. If the difference is subtle and the tapering is barely noticeable, it polishes the cut surface. That detail can be desirable sometimes, in exchange for lost efficiency. Ordinarily, you want enough elbow room to spare for efficient operation.
Gullets
The rim has a low opening before each tooth. If the open parts are big and rounded, they scoop out sawdust efficiently and help cut fast. Little gullets fill up and retain heat.
Hollow ground
A concave curved hollow ground tooth face has acute side edges. Those parts of the tip are meant to pierce easily, at least until their razor edges round over. Curved tops are found on a few rare styles. These unusual kinds of tips are vulnerable and costly to maintain. A practical alternative is HATB.
Hook angle, negative or positive
The way a saw tooth leans is called hook or rake. A radius is a line from the center to the rim. You can define a face cutting angle by its degree off the radius. Thus, zero rake is simply straight up. Positive hook angle leans forward to move stock rapidly. The disadvantage comes on overhead models where positive rake may actually try to pull too much.
Negative hook angle leans back, as in the bottom picture. The scraping of negative hook creates some resistance, which discourages pulling. Cutting angles that are gently leaning back can be beneficial when you want to push at a relaxed, controlled pace in order to gain a neater result.
Rip style teeth
The obvious feature of a rip profile is its big deep gullet. The purpose of it is to rake out dust. To go with the grain, the style of a rip table saw blade has an aggressive +20 degree positive hook angle and plenty of side clearance.
Usually a rip profile is flat on top as shown here. (Triple chip is seen on some varieties.) A flat shape is also seen on a raker, but it does not have so much hook. It sometimes has the capacious gullet. A raker opens up combination patterns which are primarily alternate top bevel. It is inserted between and slightly below the level of the groups of other tips.
TCG: Triple Chip Grind
A pattern of a high, chamfered, cornerless tip alternating with a low flat topped one goes by the names TCG or occasionally TC and F. In the face view picture, only the corners of the flat one are showing behind. Triple Chip Grind can stand up to dense, tough composites. Because the shape is beveled on both corners and balanced on center, TCG is a stable design that makes a very neat cut. Triple chip style has versatility to excel in a variety of manmade materials, and it rips well. For slicing across fibers, triple chip teeth cut somewhat rougher than alternate bevel tips.
California Triple Chip Grind is a variant of the TCG pattern. The flat tops of C-TCG have just one corner removed on alternate tips. CTCG is not so common as the triple chip style.
TCT tip
On each tooth a Tungsten Carbide Tip is inserted. The carbide grade in the tip itself may be varied to suit an application. The parts are individually secured and then shaped.
Tooth count
Since both sides of the tips cut, fewer carbide teeth are needed. Count the full number per dia. You might find a number marked such as 60T, or Z60 for zahn in German.
The tip count on a 10 in. dia. ranges from 12 to 100T. The average is around 40 or 50T. Tooth spacing makes a significant difference in rate. Closely crowded ones feed cautiously and cut hard stock cleanly, but get hot. A low count, coarsely spaced by big gullets moves without hesitation.
As saw blade dia. increases, approximately 20T are added to keep an equivalent effect. 7 1/4 in. 40T is like 10 in. 60T, and roughly comparable to 12 in. 80T.