Flat-Top Ripping Blade is King

Freud’s 24-tooth Heavy Duty Rip Blade (LM72M010) is what is installed in my table saw 90% of the time.  The blade has 24 teeth 0.126″ wide, ground flat on the top and pitched forwards at 20 degrees.  These characteristics make it the most versatile and most used saw blade in my shop.

Heavy Duty Rip Blade - Technical Specifications (from FreudTools.com) K= Kerf; P= Plate Thickness

As you would expect, this blade excels at ripping.  The 20-degree forward (positive) hook angle makes feeding stock past the blade easier and the blade leaves two clean surfaces requiring little, if any, further clean-up.  This blade also does a formidable job with cross-cuts too, especially when freshly sharpened.  (When I need a super-clean crosscut, I take the time to switch to a dedicated crosscut blade.)

For a 10″ circular saw, 24 teeth is not very many (they may have as few as four or as many as 90).  Having few teeth allows quicker, more aggressive cutting.  The trade-off is that the blade will tend to leave a rougher cut than a blade with more teeth.  In some cases, using a slower feed rate increases the quality of cut.  In other cases it only causes burning.

Freud Heavy Duty Rip Blade

The flat-top blade is useful for joinery.  Non-through cuts have square shoulders and flat bottoms, making cleanup unnecessary.  The blade has a regular kerf that is 0.126″ wide, just a little over 1/8″ (1/8″=0.125″).  This is 20% thicker than a thin-kerf blade which typically removes 3/32″ (0.09375″).  While a thicker kerf means it turns more wood into sawdust and requires more power to spin, it also means that only three passes are required to cut a 3/8″ wide groove versus four with a thin-kerf blade.

In addition to making joinery more convenient to cut, set-up is also quicker and easier.  Because each tooth is the same, the top or edge of any tooth can be referenced for accurate set-ups.  Another benefit to the tooth shape, which distributes the cutting duty over a wider surface, is that the teeth are also very durable and as a result, I need to have the blade sharpened less often.

There is a lot more information on saw blades on the Carbide Processors Inc. website.

4 thoughts on “Flat-Top Ripping Blade is King

  1. Chris for general purpose use, I like an alternate bevel, followed by one flat bottom tooth. Seems to cut the sides smoother, and the flat tooth makes a nice square bottom for joinery. I had a Forrest WWII blade, which is just an alternater bevel, sharpened so the top of each tooth was flattened but only half the width of the tooth. That makes a nice flat bottom cut, but you still have the benefit of an alternate tooth and side cut.

    I would concur with you on the thicker blade and heavier carbide. They last longer, and something about the mass of the steel keeps them running a bit cooler. Heat builds pitch on the blade… and that ruins everything.

    So what do you clean your blades with. I like turp, but only outside!

    • Morgan,

      My dedicated crosscut blade has alternate top bevel teeth. It leaves a polished surface when sharp. However, the pointed teeth are more delicate so they don’t last as long before needing to be resharpened. I use the blade when I need a finished cut. For everything else, I use the rip blade.

      That modified Forrest WWII blade sounds very interesting – an idea of which I had not thought. I think that it’s the pointed tooth that results in the quality cut, but you’ve removed that to make it perform like blade with flat-top teeth. I’m skeptical about the benefit of such a blade versus the blade I’ve described in this article. I think it’s something I’ll have to see to believe.

      Yes, pitch build up both make the blade act like it’s dull and the increased heat dulls the blade. I’ve been happy with Lee Valley’s Industrial-Strength Cleaner and Resin Remover. That said, I think it’s more important that you do regularly clean your blades than what cleaner you choose.

      Chris

  2. Since I need a new blade for my Bosch contractor saw (which I don’t use much) I may have to give this blade a try. The .126″ kerf should work well on this saw — I’ve had issues with narrow kerf blades not providing enough width for the riving knife to follow through. Again, I don’t use the saw much so I don’t experiment too much with different brands — I’ve had good luck with Freud blades.

    • Hi Ron,

      On my previous saw which I had bought second-hand, the original user had ground the sides of the splitter to allow thin-kerf blades to be used. If you do this, remember that one of the functions of the riving knife is to keep the stock from rotating away from the fence, so you should remove most of the thickness from the side opposite the fence.

      When I am concerned with wastage, I often use a 7-1/4″ circular saw blade.

      Chris

I would be delighted if you left a comment!

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s