How effective are different types of saw blades for various cuts and woods?

Question

There are different types of saw blades (e.g., rip, cross-cut, combo - based on number of teeth, edge, hook angle, etc) of saw blades for different types of cuts (rip, cross-cut, etc). How effective are these blades for each of the cuts?

There's a related question which gets into the difference between a rip and cross cut, but I'm more interested in the practicality of using a cross-cut blade for a rip cut, for instance, or how effective a combination blade is when cutting plywood. That question touches on this subject, but really only for a rip blade on a cross cut (which is bad).

What kind of clean-up or finishing work can be expected from each combination of cut and blade?

To keep this question more focused, let's look at

Three types of cuts

• rip cut
• cross cut
• cut in plywood

Four types of blades

• Rip blade

  

• Cross cut blade

• General purpose blade

• Combination blade

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Links and images are provided as examples only.

Answer 1

It seems to me your question is really, "what will happen if I don't use the recommended type of blade for a given application?"

Simply put:

• If you use a blade with too many (smaller) teeth and consequently shallower gullets, the gullets will not be able to carry away enough material and will clog, resulting in burning and possibly a wandering cut, as well as possibly binding depending on the depth of your cut and power of your saw's motor. If the blade binds and the motor does not stall, there is a good chance you will experience kickback. A workaround for this, in case you really need to get the job done with the wrong blade, is to make the cut in several shallow passes and/or using a very slow feed speed.

• If you use a blade with too few (larger) teeth and consequently deeper gullets, you will get a more jagged cut when cutting perpendicular to the grain, with chipout at the cut line which will be evident when crosscutting and when cutting plywood. Using a rip blade on plywood can produce an extremely splintered edge. There are some techniques you can use to minimize these effects, such as scoring or taping the cut line before making the cut, or putting a piece of sacrificial material on the side where the blade exits (e.g., on the top when using a circular saw or on the bottom when using a table saw).

• Combination or general-purpose blades try to find a happy medium, and will work more or less well enough on rip cuts, crosscuts, and plywood; however, they will not produce as clean a cut in plywood or crosscutting applications as a more specialized blade, and they will not work as fast as a rip blade on rip cuts.

If you only have 1 blade, it should be a combination or general-purpose blade.

Although your examples and the examples I've given focus on circular-shaped blades, the same applies to any blade, including bandsaw blades and handsaws.

Answer 2

There are many more types of blade than you're listing here. For example, the grind angle of the teeth can make a big difference. This is different from the hook angle. So instead of answering for the specific combinations, which would be hard to do anyway, I'm going to try to be general. I'm also going to assume we're talking about sharp, clean blades. Any blade that is dull or caked with resin is going to cut worse than the same blade sharp and clean.

The short answer is, using any blade for the cut it is designed for is going to give the best result. Blades designed for a specific cut will do better for that cut than other blades. General purpose blades designed to make several kinds of cuts will not make as clean a cut as a blade designed specifically for a given cut.

Generally, blades with more teeth tend to produce cleaner cuts than blades with fewer teeth. But more teeth means fewer and smaller gullets -- the gaps between the teeth -- which means they clean chips from the kerf slower. If the cut you are making produces lots of chips, or lots of bigger chips, the blade is more likely to bind.

Rip cuts produce larger chips, which means you'll get a cleaner cut using a blade with larger gullets. If you try to make a rip cut with a 10" 80 tooth blade, the blade will probably bind. If you try to go slower to prevent the binding, you're likely to be moving slowly enough that you'll scorch the wood. Note that what actually happens will depend on the depth of the intended cut, too. I can't tell you at what depth you'll move from being okay, to scorching, to binding. I can tell you from personal experience and being lazy about blade changes that rip cuts with blades not designed for it just don't feel right. You can feel the saw working much harder than it should be.

As you get to the other end, cross cuts and plywood cuts with a rip blade, you'll find the saw cuts okay, but leaves rough cuts. If you're trying to cut a nicer veneered plywood, you'll find the veneer tears.