Which blade to use when?

[ejstefl]

OK, another newbie question... I recently purchased this Irwin 60T and 80T set that was on special at Amazon.

My table saw currently has a 40T blade.

How do I know what to use, and when?

[LCHIEN]

your link is broken, but assuming they're 10" blades,
the rule of thumb is:

higher count teeth like 60 and 80 are used for fine, finishing work on crosscuts on a TS and also can be used for miter saws (altho miter saws are best done with high tooth count and a low or negative hook angle - another blade design parameter)

Low tooth counts are used for ripping, like typically 24 teeth. The larger space between teeth (gullet) are better for carrying away the larger amounts of cuttings from ripping (cutting with the grain) and 24T blades should probably be used where maximum efficiency (fastest) ripping is needed.

In between counts such as 36, 40 or 50 tooth generally fall in the "combination" category and can be used for both ripping and cross-cutting.
Some very fine blades are made in this tooth count and do a very good to excellent job of both with just minor compromises. They're great for just leaving on the saw and not having to change blades when going back and forth from ripping to crosscutting.

[SARGE..g-47]

Your 40 tooth along with 50 tooth blades is a combo blade. Meaning a comprimise between a rip (24 T or 30 T) and a cross-cut 60 T. IMO, the word compromise fits. It doesn't have enough gullet to carry away waste as a 24 T rip and it doesn't have enough teeth to give the smoother cut of a 60 T cross-cut. The manufactures offer them up knowing most can't afford multiple blades or they won't take time to change to a proper blade.

The 80 T is a super-dooper fine cross-cut for end grain or... (someone will have to tell me the answer to that one???). Smooth supposely, but I don't see the need or expense personally. It won't do anything IMO that you can't do by cutting 1mm or 2mm longer and trimming down to a glass finish with a block plane if you need a glassy finish cut for showing end grain.

Hope that helps...

[vaking]

The 80 T is a super-dooper fine cross-cut for end grain or... (someone will have to tell me the answer to that one???). Smooth supposely, but I don't see the need or expense personally. It won't do anything IMO that you can't do by cutting 1mm or 2mm longer and trimming down to a glass finish with a block plane if you need a glassy finish cut for showing end grain.

Hope that helps...

Filling in the blank:
or fine veneer as in expensive plywood. Most 80 teeth blades specify that this is what they are good for.
Returning to the original question of specific blades. In my opinion:
40 teeth blade - stays on the saw most of the time.
For large amount of ripping you may still need a ripping blade which you do not have yet.
For super fine crosscut or expensive plywood - use 80 teeth blade you have.
For cutting MDF - Either of Irwin blades will be good. It will be dead quickly as MDF is a murder on blades. That is why you do not want to use expensive blades on MDF and the ones you got ($27 for 2 blades including shipping I believe) are perfect for the task.

[Knottscott]

Your 40 tooth along with 50 tooth blades is a combo blade. Meaning a comprimise between a rip (24 T or 30 T) and a cross-cut 60 T. IMO, the word compromise fits. It doesn't have enough gullet to carry away waste as a 24 T rip and it doesn't have enough teeth to give the smoother cut of a 60 T cross-cut. The manufactures offer them up knowing most can't afford multiple blades or they won't take time to change to a proper blade.

The 80 T is a super-dooper fine cross-cut for end grain or... (someone will have to tell me the answer to that one???). Smooth supposely, but I don't see the need or expense personally. It won't do anything IMO that you can't do by cutting 1mm or 2mm longer and trimming down to a glass finish with a block plane if you need a glassy finish cut for showing end grain.

Hope that helps...

In addition to some of good points already made, I think it's worth noting that not all blades are created equal. The tooth count is one aspect that influences cut, and the rules of thumb hold true IF all other characteristics are equal, but there's alot more to the science of saw blades than tooth count, and all is rarely equal. Other aspects are the quality of the carbide, the degree of sharpness, the hook angle, type of tooth grind, side clearance, relief angles, the quality of the alloy effects stiffness, expansion slots, and there are several other aspects. Plus there are several methods of varying all of those to achieve good (or poor) results.

My Forrest WWII 40T general purpose blade and comparable Ridge Carbide TS2000 are indeed a compromise in the extreme ranges compared to a high quality dedicated rip and crosscut blades, but do a very good job in a wide range of materials and cuts so that the same blade can be left in place most of the time. They make cleaner cuts than all but one of even "good" quality $45-$65 60T blades I've used, and they put some of the more average 60T $20 blades to shame....never tried a lower grade 80T. They also rip better than most of the average quality 24T-28T blades I've tried. They fall short when compared to the ultra fine crosscut of something like a Freud F810 80T or Forrest Duraline Hi-ATB blade in crosscutting, and don't rip as aggressively as a good quality 24T ripper like my Leitz or DeWalt (although they do leave a cleaner cut).

How long a blade holds it's edge is another factor....I've had several that went dull quickly. Quality is even more elusive than a blade's specs, and quality varies between manufacturers quite a bit. It's like comparing watts in a stereo receiver, battery voltage of a cordless drill, or CFM on a DC....it's difficult to glean anything useful for a performance comparison from those numbers. I've learned not to buy a blade based solely on tooth count, carbide teeth, or price.

If I had an 80T with an acceptable hook angle, I'd probably leave it in my CMS, and use the 60T for crosscutting in the TS or when I wanted cleaner rip cuts in thinner materials. For veneers or good plywood, you can always plunk the 80T in the TS then.

[drumpriest]

Dustmight, you should yell at sarge for his apparent lack of the correct usage of the term "combination blade", like you did me in the last post regarding this question.

Not ALL 40-50 tooth blades are "combination blades", but they are typically general purpose. If we are going to be semantically picky on this forum, we should at least be consistent.

[Knottscott]

Dustmight, you should yell at sarge for his apparent lack of the correct usage of the term "combination blade", like you did me in the last post regarding this question.

Not ALL 40-50 tooth blades are "combination blades", but they are typically general purpose. If we are going to be semantically picky on this forum, we should at least be consistent.

OK...somebody's gotta do it! "HEY SARGE!" The term "Combination" blade can mean one of two things....a combination of tooth grinds...most commonly an ATB/R configuration found on the 50T blades, or a general purpose blade intended for a combination of ripping and crosscutting, like a 40T GP blade. Either way, it is semantics, and both cover the same range.

The balance of the earth just improved.

[davidtu]

I use this Freud thin kerf Rip Blade, and especially if you have a BT3100, you will love it....

http://www.amazon.com/gp/product/B00...637400?ie=UTF8

but I got it on sale.


QUESTION:

Do you not do *ANY* MDF work w/ a good blade or what is the threshold of number/lenght of cuts for which you'd recommend switching out the blades? I guess I'm asking how fast does MDF dull the blade?

[MilDoc]

Best and simplest explanation I've ever seen! Thanks!

[drumpriest]

David, I only use cheap blades for cutting MDF, unless it's veneered MDF. The cut with a cheap blade is still quite nice with MDF, so it isn't a big loss. I use B&D blades that I got at HD for 20$ for a pair.

[SARGE..g-47]

Man, that drumpriest and Dustmight are mean, mean, mean. Draggin' me into the fine-tuned and refined world of semantics.... :>)

OK.. I will agree to call them general purpose blades..... If.. If.. If....... you guys explain the to OP the whole story of when and what over-all choices he has when using a 24T, 30T, 40T, 50T, 60T or 80T. He might need to factor positive or negative hook, laser cuttiing, tri-metal brazing, plate thickness, kerf width, expansion slots, carbide grading and it's relation to sharpening, flat tooth vs ATB and of course why he should chose a different blade for a sliding compound mitre as opposed to a TS with over 3 HP or under 3 HP for cross-cutting or ripping. he..............

And just as soon as ejstefl has acknowledged that he has "got it" down pat, you will never hear me use that ugly "no-no" term again on a public forum. Life was simple back in the early 70's when you had nothing but a hollow ground planer blade to get a smooth cut and a rip blade to tear it down the center.

But... in the meantime, I've got to go clean pitch build-up from my Combo blades. ha.. ha... ha..ha..ha..

You guys have a good evening.. and of course I'm just a kiddin'. :>)

[LCHIEN]

man, I'm glad those guys didn't jump on me...

[SARGE..g-47]

Man, that drumpriest and Dustmight are mean, mean, mean. Draggin' me into the fine-tuned world of semantics.... :>)

OK.. I will agree to call them general purpose blades..... If.. If.. If....... you guys explain the to OP the whole story of when and what over-all choices he has when using a 24T, 30T, 40T, 50T, 60T or 80T. He might need to factor positive or negative hook, laser cuttiing, tri-metal brazing, plate thickness, kerf width, expansion slots, carbide grading and it's relation to sharpening, flat tooth vs ATB and of course why he should chose a different blade for a sliding compound mitre as opposed to a TS with over 3 HP or under 3 HP for cross-cutting. he..............

And just as soon as ejstefl has acknowledged that he has "got it" down pat, you will never hear me use that ugly "no-no" term again on a public forum.

But... in the meantime, I've got to go clean pitch build-up from my Combo blades. ha.. ha... ha..ha..ha..

You guys have a good evening.. and of course I'm just a kiddin'. :>)

[SARGE..g-47]

And don't ask me how I got the double post? Life was simple back in the 70's when you cross-cut with a hollow ground planer blade and ripped down the center with a 24T flat. And they hadn't got around to inventing these #@@# PC's! ha.. ha...

Going to bed... :>)

[drumpriest]

Sarge, love the post, made my laugh greatly, thanks.