Difference between combination and general purpose blade?

[Bobby O'Neal]

Is there any difference? Tooth grind, angle? Marketing ploy?

[Jerome Hanby]

I always thought the later was the short definition of the former...

[Bruce Wrenn]

A combination blade generally has sets of five teeth, followed by a deep gullet. First tooth in set is usually a flat top raker, followed by four ATB teeth. A general purpose blade generally has 40 teeth, all of which are ATB. But now Forest and some others make a general purpose blade (40 tooth) with a every fifth tooth being a raker.

[Joe Spear]

I think the terms mean the same thing. However, having said that, there are differences among individual blades, including number, grind, and angle of teeth, and general cut quality. I like the Forrest Woodworker II and the Ridge Carbide 40-tooth blades. The Freud Fusion is also very good (although it didn't stay sharp as long for me as the other two). There are also excellent DeWalt, Tenryu, Infinity and other brand blades. I even have a couple of $10 Harbor Freight blades that are much better than I would have expected.

There are also woodworkers who would not even consider a combo blade but go for specialty blades, depending on the cuts they are making--crosscuts, rips, plywood and other laminated goods. Mostly I use combination blades for all kinds of cuts, but for rips in thicker stock, I do use a Systematic 24-tooth rip blade or a 30-tooth WW II. And I use a WW Duraline HI/AT blade for high quality plywood.

Some people are more passionate than I am about their blade-type opinions. It's like most other things: there's no arguing with taste. Eventually you will have your own opinions also.

[Van Huskey]

Frankly most any of the blade descriptions should be taken with a gran of salt, you need to look very carefully at the specs and you can tell what the blade will do, assuming it is well made and made to the published specs.

An example, if you look at the blade specs you can tell why Joe found the 40T Freud Fusion to dull quicker than the 40T WWII. The teeth on the Fusion are ground to give you a finer finish which in this case means it dulls quicker BUT doesn't rip as well as the WWII.

[Tom Walz]

Roughly, roughly
- Combination saw blades are contractor level blades.
- General purpose blades are handyman, homeowner blades.
- Serious hobbyists and production facilities use special blades for the tools and materials (e.g. rip, crosscut, melamine, plywood. etc.)
- Top End Professionals use custom blades generally with 20 extra teeth (as in 60 instead of 40 for ripping and 100 instead of 80 for cross cutting.) These are specifically designed for the machines, the materials and the overall use. They are generally about the same price as top end retail blades form big box stores.

The following descriptions are from Popular Tools Saw blades. These are sold only by professional level shops and are intended for extended use where cut quality is extremely important. Other companies may describe things differently

Popular Tools Saw Blades – Combination
Combo saw blades are designed for all around use, when acceptable rips and crosscuts must be made with one saw blade. The larger gullets allow deeper cuts and efficient saw dust escape on rip cuts.

Two blades offered
40 and 50 tooth
ATB+R Grind
Both 15 degree hook angle

Popular Tools Saw Blades – General Purpose - Alternate Top Bevel Grind
These general saws are designed for every day sizing and cutting of natural woods. A higher number of teeth provides a finer edge to the cut, but should be used only on thinner material. The saw blades designated by the prefix GAM contain Micro-Sheen C-4 sub-micron carbide, which provides longer tool life. The blades designated by the prefix GAL have laser cuts in the body to help reduce noise.

Nine blades offered
All alternate Top Bevel Grind
40, 60, 80 and 100 tooth counts
All 10 degree hook angle


Popular Tools Saw Blades – General Purpose - Triple chip grind
These saws are designed for high production cutting of natural woods, plywood, chipboard, and MDF. The TCG teeth offer less wear than the ATB with nearly the same quality of cut. Blades designated by the prefix GTM contain Micro-Sheen C-4 sub-micron carbide, which provides for a longer tool life. The blades designated by the prefix GTL have laser cuts in the body to help reduce noise.

Ten Blades offered
All triple chip grind
40, 60, 80 and 100 tooth counts
All 10 degree hook angle except a melamine blade which is -5 degrees

[Howard Acheson]

Technically, a 50 tooth blade with a large gullet after every 40 teeth is a Combo Blade. A 40 tooth blade with no large gullets is a General Purpose Blade.

[john lampros]

I've tried "combo" blades with little success. its seems to me they did a poor job of everything no matter how much they cost.

[Ole Anderson]

If I need a blade in the TS for miscellaneous, non-critical projects, I keep a 50 tooth combination Oldham Woodworking Wizard 1/8" thick blade which I purchased at a woodworking show probably 12 or 15 years ago, I have had it sharpened about 6 times. When sharp it does a very nice job of ripping and an acceptable job on crosscutting both solid and plywood. Heavy carbide intended for a lot of resharpening. Frankly it does as good a job on ripping as my Freud 24 tooth 1/8" resaw ripping blade. Ripping 8/4 hardwood, and out comes the Freud. I just picked up a 80 tooth Freud Ultimate Cutoff 1/8" blade for critical TS crosscutting like rails and styles and drawers as well as small plywood projects.

[Tom Walz]

Dear Mr. Lampros:

I agree with you.

From my experience, it seems to depend on your level of sophistication and what you consider good cuts. It is pretty hard to create a multi-putpose tool that gives the same kind of results as tools specifically designed for a task.

I always sort of cringe when someone says they will use a multi-purpose blade for Melamine, for example. However some folks are happy and don't mind doing touch-up filing.

Tom

[Bruce Wrenn]

Dear Mr. Lampros:



I always sort of cringe when someone says they will use a multi-purpose blade for Melamine, for example. However some folks are happy and don't mind doing touch-up filing.

TomI used dedicated melamine blades and still have to fix a few dings. It's the nature of the beast (melamine.)

[Steve Baumgartner]

I believe the difference is marketing rather than technical and that the terms are essentially equivalent in that neither of them implies a specific design. Both terms mean to imply that the blade can be used both for ripping and crosscuts, which is supposed to be attractive to the amateur who doesn't want to invest in single-purpose blades or dedicated rip vs crosscut stations, and also doesn't want to take the time to change blades between cuts. My experience has been that a good-quality, freshly sharpened combo blade does a decent job, but as they start to dull the consequences of the compromises between rip and crosscut design become more evident - tear out on crosscuts, and binding or burning on rips.

Steve

[Ole Anderson]

My experience has been that a good-quality, freshly sharpened combo blade does a decent job, but as they start to dull the consequences of the compromises between rip and crosscut design become more evident - tear out on crosscuts, and binding or burning on rips.

Steve

As with most woodworking tools, scary sharp trumps sort-of sharp. Saw blades are no exception. My just-sharpened Wood Wizard combination blade just did a remarkable job crosscutting some plywood, but once it starts to dull, it will start unacceptable tear out.

[Bobby O'Neal]

What makes the compromise easy for me is that I will rarely go straight from the table saw to the finish. Joinery will be cut or a profile made or a few passes with a plane. I need an accurate and fairly clean cut but not glue edges and 100% tearout free end grain.

[Phil Thien]

I know this doesn't work on cherry (burning), but...

If I slow the feet rate by half, have I not essentially doubled the teeth on my blade?

[Van Huskey]

I know this doesn't work on cherry (burning), but...

If I slow the feet rate by half, have I not essentially doubled the teeth on my blade?

I would say that is a logical hypothesis assuming the grind of the teeth is exactly the same. The teeth being ground the same would be rare on blades designed with half the teeth as another blade and the same diameter.

[Phil Thien]

I would say that is a logical hypothesis assuming the grind of the teeth is exactly the same. The teeth being ground the same would be rare on blades designed with half the teeth as another blade and the same diameter.

I guess my point is, there just doesn't seem to be enough of a difference between dedicated blades and GP blades to go through the trouble of switching all the time. I can alter my feed rate slightly and have a far greater impact on the quality of cut than I'd be able to achieve by swapping blades.

[Tom Walz]

Dear Mr. Thien,

In my opinion, you pretty well summed it all up.