Can a combo blade rip without burning?

[Phil Thien]

After 10 years is there any chance your CMT blade has become dull and/or dirty? The Freud Industrial, Irwin Marples, Infinity Combomax, and Tenryu RS25550 are all ATB/R blades if you're interested in replacing it with a comparable design.

With that said, a good 24T dedicated rip blade should be considerably more efficient at ripping than a 50T combo or 40T general purpose blade....it's simple physics, as is the rougher cut it leaves, though many are marginally capable of leaving a glue line edge.

Please explain the simple physics.

[scott spencer]

If all else is equal, fewer teeth means less resistance and a more aggressive cut.

[Clint Olver]

Since I got my Infinity combo blade http://www.infinitytools.com/10-Comb...tinfo/010-050/ , I haven't used my dedicated rip or cross cut blades. I have a 40T CMT blade too, it was okay, but not as good as the Infinity. Of course, if your blade isn't sharp, it won't be good at anything.

C

[Rich Engelhardt]

I find it far easier and quicker to change blades and eliminate burns marks that it is to deal with the burn marks once they are on/in the wood.

[Phil Thien]

If all else is equal, fewer teeth means less resistance and a more aggressive cut.

But if all else is equal, the blade with fewer teeth is taking "bigger bites" which increases resistance.

[Matt Meiser]

I use a 40T combo blade almost all the time but if I'm ripping something that thick I switch to a rip blade.

[Ray Newman]

"...far easier and quicker to change blades and eliminate burns marks that it is to deal with the burn marks once they are on/in the wood. "
--Rich Engelhardt

BINGO!

[Bill Huber]

I have had a few different combination blades and have not really been very happy with them in the area of ripping. I got a Guhdo Gmaxx at the woodworking show and I am hook on the Gmaxx blade. The cuts are very clean and smooth, I was really happy with the smoothness of the cut.

It is a 50 tooth, ATB, carbide tipped glue line general purpose blade and it rips just about as good as my 24 tooth rip blade. On top of how good it works it is cheap when you look as some of the others out there.

http://www.amazon.com/Guhdo-Gmaxx-Se.../dp/B0060H1MDG

This is my go-to blade now on my little Jet table saw.

[johnny means]

Not true. The mechanics of ripping versus cross cutting are very different. When ripping, the material tends to want to cleave with the grain. This causes the chips to come if the board in a ribbon shape. Picture the way a hand plane creates a long shaving. This shaving is then forced into the gullet. Less teeth equals larger gullets which allows the tooth to make it through the cut without clogging up. This shaving action actually does create more resistance on a single tooth. Teeth spaced further apart allows for less actual cuts to be happening at any given moment. The most simple way I can describe the difference between ripping and crosscutting is to compare it to cutting firewood. How much effort does it take to cut down a 1ft diameter tree? How much much easier is it to split a 1ft long log?

[David Weaver]

A simple smoothing plane solves the burn problems. Very little work, and no change more than a couple of thousandths in the width of the board - something you'd probably solve more unevenly by sanding, anyway.

[Chris Fournier]

But if all else is equal, the blade with fewer teeth is taking "bigger bites" which increases resistance.

Yes but no. Grain orientation which is really the heart of the matter is the practical variable all things being equal or not and cross cutting vs ripping are two different games. If we are talking about ripping, the limiting factor to feed speed is the clearance of the "shavings" vs the "chips" that you get from cross cutting. A proper ripping blade has a different tooth configuration of course and a gullet that can transport the large volume shavings.

[Phil Thien]

Yes but no. Grain orientation which is really the heart of the matter is the practical variable all things being equal or not and cross cutting vs ripping are two different games. If we are talking about ripping, the limiting factor to feed speed is the clearance of the "shavings" vs the "chips" that you get from cross cutting. A proper ripping blade has a different tooth configuration of course and a gullet that can transport the large volume shavings.

Nobody here hand-feeding stock is packing gullets. Well maybe if you're cutting 2.5"+ material with a strong saw and maintaining a fast feed rate, you could pack a combination blade's gullets. But you'd have to be feeding pretty darn fast.

[Chris Fournier]

LOL, I respectfully disagree.

I used to notice a big difference back in the day when I used steel (non-carbide-tipped) blades.

With carbide, not so much.

PLEASE ANYONE READING ROD'S POST: There may be a tendency for someone reading that to try pushing stock into a rip blade faster than they're accustomed to doing so, to see how it works. Don't.

What saw do you use Phil? What blades? I would agree with Rod, a rip blade rips faster than a combo blade, you can feed it faster than a combo blade, it is after all designed for ripping and the cutting geometry and gullets are designed to "plane" wood and extract the rather large shavings efficiently, a combo blade can't cut as efficiently nor remove the swarf as well.

[scott spencer]

But if all else is equal, the blade with fewer teeth is taking "bigger bites" which increases resistance.

Think of it this way....the teeth create friction when contacting wood at high speed....more teeth creates more friction. "Bigger bites" is really a function of feed rate....if the feed rate remained the same, the blade with fewer teeth has less resistance and runs cooler. The combination of having fewer teeth making less contact and efficiently removing the material from the kerf (less resistance and heat), actually allows for a faster feed rate.

[Larry Edgerton]

I have 4 saws, so I will usually have a combination blade in one of them just for convenience. But....

Same saw, 4 hp, same wood, same power feed, both FS Tool blades in new condition, I can not run as fast a speed on the feeder with the combo blade, and the rip blade gives a better cut.

Sorry Phil, you are just wrong on this one.

Larry