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Help Understanding the Freud Ripping Blades

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Forum topic by DavidNJ posted 01-02-2013 06:02 AM 1833 views 4 times favorited 17 replies Add to Favorites Watch
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DavidNJ

387 posts in 744 days


01-02-2013 06:02 AM

I’m new to this at this level, and start these threads when I get stumped. I’m stumped.

Freud lists 5 different ripping blades.:

  • LM74, ICE or Permashield, 30 tooth TCG, stock 1/8” to 1”, .118 kerf
  • LM75, Permashield only, 30 tooth TCG, stock 1/8” to 1”, .091 kerf
  • LM72, Permashield or ICE, 24 tooth flat, 3/4 to 2 3/4”, .126 kerf
  • LU87 Permashield only, 24 tooth flat, 3/4” to 2 3/4, .094 kerf
  • LM71, ICE only, 18 tooth flat, 1 1/2” to 3 1/2”, .177 kerf

Then they also have the Diablo

  • D1024X, Permashield only, 24 tooth ATB, .098 kerf

Is the only reason for the thin kerf for lower power saws (1.5hp-2hp)? Would the wider kerf blades still work ok in these machines or should the thin kerf be used? Does a 3hp machine benefit from a thin kerf?

Are the wider kerf blades, which seem to have a thicker plate, always preferable?

Would you typically have both the 30 tooth TCG and 24 tooth flat for different thicknesses?

Do you need a different zero clearance insert for each or can blades with kerfs within .01” share the same insert?

The TCG and flat both have flat teeth. The ATB doesn’t. Isn’t that unusual for a ripping blade? Is that a reason to avoid the Diablo?

Thanks,

David


17 replies so far

View knotscott's profile

knotscott

5606 posts in 2126 days


#1 posted 01-02-2013 10:42 AM

The 30T “GLR” rippers (LM75/LM74) are only intended for material 1” or less, which is a very narrow operating range…. they don’t crosscut well, and they tend to burn in thicker materials, so a lower tooth ripping blade is still a requirement for most of us. You can achieve the same “glue line” edge from a decent 40T or 50T combo blade, many 60T blades, and many of the better 24T bulk rippers also have the potential for a glue line edge. The triple chip grind (TCG) gets good edge life, and is a good choice for high volume or particularly abrasive materials like MDF or teak. Unless you’re using your saw specifically for the 1” or less material, the 30T GLR blades aren’t really necessary IMHO, and don’t add much capability. I use a 40T or 50T combo blade for most of my smooth ripping, and use a 24T for thicker ripping. The term “Glue Line Ripper” is largely a marketing tool. The blades work, but are blade that few of us really need….it’s almost too specialized.

The 24T FTG bulk rippers (LM72/LU87) are the standard ripping blade for thicker materials that most blades struggle with. They cover a range that few other blades will cover, so are a very useful blade to add to your arsenal. The flat top grind is considered the most efficient for heavy duty ripping. They’re also useful for any cut where a flat bottom kerf is desired…a flat top grind is the only grind that will leave a truly flat bottom. The D1024X is an ATB ripper that’s generally intended for smaller saws, but it’ll work fine for the same ripping operations as other 24T FTG blades. The ATB grind gives it some ability to crosscut, but the low tooth count works against you for that purpose, so crosscut results will be marginal. The 18T rippers are an exaggerated version of the 24T rippers for extra thick ripping…they will leave a rough cut, but will chomp through the thicket materials more easily given a saw with sufficient power.

Kerf width is a matter of preference depending on your saw and the material being cut. A 1/8” full kerf blade is 33% wider than a comparable 3/32” blade, and requires proportionately more power to spin. Most 1.5 to 2hp saws will spin a full kerf blade, but they labor harder in the process. A true 3hp to 5hp motor should have no issues with a full kerf blade…..you can use a TK blade if you like with a bigger motor, but there’s less incentive to do so. Thin kerf blades can also save some material, though the savings are marginal for most hobbyists. For every design parameter there are pros and cons….few aspects are absolute. Full kerf is inherently more stable than TK, but most of the better TK’s work well and are beneficial to smaller saws. Quality and sharpness are always preferable.

Most of what I know about saw blades can be found in this blog....

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View Lee Barker's profile

Lee Barker

2169 posts in 1601 days


#2 posted 01-02-2013 04:03 PM

I’d just like to say here, knotscott, that that is the best response to a question I have ever read on LJ.

Detailed but not obscure. Thorough and focused. Plus a link to more if any of us are even more curious.

I am impressed.

Thank you for paying attention to the questions and sharing your knowledge. And thanks, David, for a clear and detailed question.

Kindly,

Lee

-- "...in his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"

View Cosmicsniper's profile

Cosmicsniper

2199 posts in 1909 days


#3 posted 01-02-2013 04:25 PM

Hard to add anything to Scott’s awesome post.

I will say that, regardless of the saw, thinner kerf blades make a huge difference in perceived power. This is a large reason why people with 110/120v contractor saws feel like they need nothing more when using a sharp thin kerf blade. The difference is easy to see on 3 hp saws as well. For example, I always used thin kerf blades, and kept doing so when I got my 3hp Unisaw about four years ago. When I purchased a full-kerf Forrest WWII blade to go with my new Incra TS fence, I was a little disappointed with the blade…which is silly if you know how good those blades are. But I wasn’t prepared for the loss of what I felt should have been easy cuts compared to the thinner blades.

Since then, I’ve adjusted feed rates and expectations…and I need to do a better job of keeping my blades clean and sharp. But I still use the full-kerf blade 85% of the time. The value of that is that I can easily compute 1/8” from my Incra cuts to allow repeated cut pieces to fall off the left side of the blade…which takes advantage of the safety and accuracy of the Incra system (no need for a jig to cut narrow strips next to the fence). This is why I bought the full-kerf blade…easier math.

-- jay, www.allaboutastro.com

View Manitario's profile

Manitario

2378 posts in 1634 days


#4 posted 01-02-2013 06:37 PM

well, I was going to leave a helpful reply to this until I read knottscott’s…I can’t possibly say anything better!
For the record, I use a Freud Premier Fusion 40T full kerf blade as my general day to day blade and a thin kerf 24T Freud blade for ripping rough stock. I use the same ZCI for both…

-- Sometimes the creative process requires foul language. -- Charles Neil

View pintodeluxe's profile

pintodeluxe

3564 posts in 1564 days


#5 posted 01-02-2013 07:17 PM

The Diablo 1024 is actually a great blade. Thin kerf, and it stays very sharp. I clean it once in a while, but that’s it. My Freud industrial 50 tooth combination blade doesn’t get much use since I started using the 24 tooth rip blade. I still use the combination blade for cutting grooves and joinery.
I use separate ZCI’s, but I make my own so no big deal.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View HorizontalMike's profile

HorizontalMike

6968 posts in 1665 days


#6 posted 01-03-2013 12:58 AM

The LM72 ICE 24T Flat cut blade is my favorite blade. I bought a second one for whenever I need to replace/sharpen the first. Once I have my 8/4 or 12/4 resawn I will still use this blade to rip longer pieces. My crosscut blade is a Frued Diablo 50T ATB.

And +10 for Knotscott’s full explanation for sure!

-- HorizontalMike -- "Woodpeckers understand..."

View JesseTutt's profile

JesseTutt

811 posts in 861 days


#7 posted 01-03-2013 01:28 AM

I have a Freud 24 tooth rip blade and use it to cut any thickness. It is a flat grind so that I can use it for dados, etc.

I like the 1/8 inch kerf blades. That width makes it much easier for me to rip thin slices on the cutoff side of the blade. I know that I need to move the fence 1/8 + the desired thickness. I tried the 3/32 blade and had more problems doing the math in my head for multiple cuts.

-- Jesse, Saint Louis, Missouri

View DavidNJ's profile

DavidNJ

387 posts in 744 days


#8 posted 01-03-2013 01:34 AM

Thanks to Scott and everyone for your input. Lots to chew over.

Let me see if I got it. Everyone agrees that the 24T ripping blade with a flat kerf, 20°, and anti-kickback design is useful for ripping thicker (over 1”) materials.

The 30T ripping blade with TCG teeth cuts better than the 24T on thin material, but isn’t better or as good as the 40T ATB blades from Forrest and Freud.

While not discussed here explicitly, the Freud ratings indicates their own general purpose and combination blades’ cut quality is inferior to their new 40T ATB.

Which brings us to the 40T ATB blades: the Freud Perfect Fusion which Rob extolled and the widely used Forrest Woodworker II. There is more information of the Freud. It is a “Hi-ATB” design where the angle is 30° compared to the 10° on the other combination blades and 15° to 20° on the crosscut blades. The hook is 18°, near the 20° of the 24T ripping blade and much grader than the 10° of the crosscut blades and the 10°-to-13° of the other combination blades. It also has Freud’s double side grind which they say is partially responsible for its clean cut surfaces.

Are the 40T new technology combination blades—the Freud Perfect Fusion and Forrest Woodworker II—the replacement for other combination blades? Are they the replacement for other crosscut and ripping blades also?

View kizerpea's profile

kizerpea

746 posts in 1118 days


#9 posted 01-03-2013 01:34 PM

Yep the hook angle makes a diffrence to..i run a -5 deg on the miter saw…..one of the first things i learned about…this is a good topic for lots of woodworkers…

-- IF YOUR NOT MAKING DUST...YOU ARE COLLECTING IT! SOUTH CAROLINA.

View b2rtch's profile

b2rtch

4351 posts in 1799 days


#10 posted 01-03-2013 02:15 PM

“And +10 for Knotscott’s full explanation for sure!’
Amen.
I always bought Freud blades and I never used combination blades but after Lumberjoe’s review I bought a Irwin Marple combination blade. I am equally impressed with it. It cuts very well and very smooth.
Unfortunately I already got a nail with it.

-- Bert

View camps764's profile

camps764

827 posts in 1111 days


#11 posted 06-02-2013 01:55 PM

Bump – this is an awesome thread and just answered a TON of questions I had this morning.

-- Steve

View Bill White's profile

Bill White

3587 posts in 2711 days


#12 posted 06-02-2013 02:11 PM

Just a quick add-on.
We started using the Ice 10” x 18 tooth ripper at work. We rip a lot of SYP and Heart Pine, and found that the 18 tooth, ful kerf runs cooler thus not “cooking as much rosin out of the woods. I’m not having to clean blades nearly as often.
Billl

-- bill@magraphics.us

View BBF's profile

BBF

141 posts in 590 days


#13 posted 06-02-2013 02:41 PM

Good discussion great answer Knotscott.

-- I've never been disappointed buying quality but I have been disappointed buying good enough.

View MrRon's profile

MrRon

2985 posts in 1994 days


#14 posted 06-02-2013 03:39 PM

Knotscott’s blog says it all. I would like to add; any blade that bogs down in a cut will burn the wood and the blade if the RPM’s drop. A saw with 3 or 5 HP will keep the speed constant. So whatever blade you use, the important thing is to not allow the speed to drop. If a TK blade is needed to keep the speed up, then that’s the right blade to use

View TopamaxSurvivor's profile

TopamaxSurvivor

15088 posts in 2427 days


#15 posted 06-03-2013 03:47 AM

What does “ICE” stand for?

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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