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Thread: 10 deg fleam 25 deg rake

  1. #1
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    10 deg fleam 25 deg rake

    I recently made a post about a saw that I put a new handle on and sharpened it cross cut using 12 degrees fleam and rake. The saw is sharp and cuts fast, but is not cutting to suit me.

    I decided to check the the rake and fleam on other crosscut saws that I own.

    The first is a LN carcass saw sharpened crosscut. The other is an old Disston 4. I was surprised that they both have the same rake and fleam.
    I was almost stunned, they are sharpened at 10 degrees fleam and 25 degrees rake. They both are well behaved saws.

    How does this sit with how your cross cut saws are sharpened?

    For what it's worth, the Disston, like the one shown here, is probably 60 years old. I bought it as new old stock about 10 years ago. When I received it, the saw plate would oil can. I was able to put it in a vise and tension the saw plate which solved the issue. I learned about doing that on this forum. I'm pretty sure the tip came from George.


    Last edited by lowell holmes; 03-06-2016 at 4:59 PM.

  2. #2
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    Are you sure you don't have the 10 fleam and 25 rake stated in reverse? 10 fleam sounds rough, and 25 rake sounds slow. How many TPI?

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    Quote Originally Posted by Tom M King View Post
    Are you sure you don't have the 10 fleam and 25 rake stated in reverse? 10 fleam sounds rough, and 25 rake sounds slow. How many TPI?
    http://www.blackburntools.com/articl...les/index.html

    Checking the site above, fleam is the horizontal angle of the trailing edge of the tooth and rake is the vertical angle of the trailing edge.

    The tooth count is 14 tpi on all three saws.

  4. #4
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    I don't understand using "horizontal angle of the trailing edge", or "vertical angle of trailing edge". Fleam is the angle of the cutting face off perpendicular to the length of the plate, and rake is the angle of the cutting edge relative to vertical. (I'm sure I didn't explain that clearly) I asked about the tpi since sharp is more important than geometry as teeth get smaller, but at 14, the geometry matters.

    copied and pasted from your link: " Fleam (sometimes called bevel) is the angle that the front of the tooth makes with a line drawn perpendicular to the plane of the saw plate"

    "Rake is the angle that the front of the tooth makes with a line drawn perpendicular to the point line, and lying in the plane of the saw"

    The way I've always heard it stated, when talking about saw tooth geometry, it goes in the order of rake and fleam. In other words, when talking about a crosscut saw, it would be said that it's "15 and 25" (as an example). It would be taken for granted that the first number was rake, and the second number fleam. I never heard anyone say, " it has 15 degrees rake, and 25 degrees fleam". It would have simply been said, "it's 15 and 25".
    Last edited by Tom M King; 03-06-2016 at 10:23 PM.

  5. #5
    I am sure you are right Tom. For one, I always describe tooth geometry the way you said, rake first, fleam second. For two, I can't imagine cutting with 25 degrees rake. Speed starts to nosedive almost exponentially when the rake gets much below 10, in my experience.

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    Quote Originally Posted by Steve Voigt View Post
    I am sure you are right Tom. For one, I always describe tooth geometry the way you said, rake first, fleam second. For two, I can't imagine cutting with 25 degrees rake. Speed starts to nosedive almost exponentially when the rake gets much below 10, in my experience.
    I saw the initial post and decided not to comment, but FWIW I also find 25 deg rake to be rather surprising. Some reviewers have described that saw as having "relaxed rake", but usually that means 15 deg or thereabouts.

    The teeth on Western saws have a total tip angle of 60 deg, so if the leading edge has 25 deg rake then that means the trailing edge has 35. In other words it's close to being a bidirectional saw (neither push nor pull) with symmetric peg teeth.

  7. #7
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    Hi Lowell.
    I believe you misread Issac's site. Should be 10* rake and 25* fleam. The rake is fairly aggressive for a cross cut saw, but not a rip saw. The 25* fleam is pretty common on a cross cut saw. Especially for softer woods. I use it a lot. My rip saws very often have 8* to 10* rake. This makes them start easier without too much loss in aggressiveness given the hang angles I use. Think about it this way. If you hold a scraper in your hand and lean the top forward to scrape, you are mimicking the saw tooth rake. If you then skew the scraper to one side a little, the way you would a plane, you have introduced fleam to make the scraper slice better. FYI: Saw teeth are actually more like little scrapers than chisels. They lean forward at the top or Gullet as you are looking at the saw in the position of use. If you flip the saw upside down, they then appear to be leaning backwards. I am not sure who originally started referring to them as little chisels, but that's not correct with regard to back saws. Take a look at the bottom of the page. Hope this helps. http://www.bontzsawworks.net/ramblings/

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    Looking at the saw in the saw vise, the teeth being pointed up, I laid a 4"xxs file in the gullet.

    The horizontal angle the file made with the saw plate was 80 degrees.

    The vertical angle the face of the tooth was 25 degrees from vertical.

    It's all a matter of semantics.

    The real purpose of my post was to observe that the Lie Nielsen and the old Disston saw had the same tooth geometry.

    Can you guess what my home sharpened crosscut saws will have?

    Why don't some of you make the same comparisons?

    Also, I have the Lee Valley saw file holder. The angles I posted were read from the holder. I did not estimate the geometry.
    Last edited by lowell holmes; 03-07-2016 at 9:25 AM.

  9. #9
    Looks like it is time for a picture!

    (But it ain't too easy to photograph small saw teeth).

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    This is what I call fleam.fleam1.jpg

  11. #11
    Yes, that's fleam. Now I really would like to see those LN and Disston teeth!

  12. #12
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    I usually like less rake rather than more, so I've never had a saw in my hand with that much rake. As for fleam on a crosscut saw, I've tried, used, and liked sometimes, a bit less fleam than the commonly used 25, but never anything that approached 10 degrees. So those saws would be totally new territory for me. I would be willing to bet money that I wouldn't like them at that geometry.

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    http://www.vintagesaws.com/library/primer/sharp.html

    Rip Tooth Geometry

    Rip Teeth, like crosscut teeth are perfect 60 degree angles. However, unlike crosscut teeth, rip teeth have a very steep rake angle, from 0 to 8 degrees. In the beginning of modern hand saw production, all rip saws had teeth with a zero degree rake. Saws with a zero degree rake (tooth edge perpendicular to the edge of the blade) are very aggressive and quick cutting. However, they are challenging to start a cut if you are not an accomplished sawyer. In the early part of the 20th century, most of the saw makers began to relax the rake angle on their rip saws to make them easier to start. Disston choose an 8 degree rake angle as the best compromise between ease of starting the cut and aggressiveness of cut. Since rip teeth are large and easy to file, I recommend that unless you are experienced, you start with a rake closer to 8 degrees, and gradually reduce it until you find the best compromise between ease of cut and speed of cut. I strike a compromise and file most of my rip teeth at 4 degrees, finding it the most comfortable for me.


    Cross Cut Tooth Geometry
    Crosscut teeth are by far the most complex of the two types of saw teeth. Crosscut teeth can be found in sizes from 5-16 points per inch (ppi) with 7-10 being the most common. If you look at the diagrams to the right, you will see that each crosscut tooth is a perfect 60 degree angle. It is no accident that all saw filing files are 60 degrees as well. There are several angles that you will have to keep in mind when thinking about crosscut teeth. The first is the rake angle. By rake, I am describing how much the cutting edge of the saw tooth is sloped back from perpendicular. The most common rake angle is 15 degrees. In general, the steeper the rake angle, the more aggressive the saw will cut. However, saws with steeper rake angles are also more difficult to start. I find that anything from 12-15 degrees is best. I tend to file my saws closer to 12 degrees, as I have no lack of experience in getting a saw to start cutting. If you are a beginner, you may find that a 15 degree rake is more comfortable. As you gain experience, experiment with different rake angles until you find one that you prefer.


    Practical Fleam Angles

    Like anything, there are some compromises which determine what fleam angle to use. For general use, 20 degrees is best. The higher the fleam angle, the more delicate the edge of the saw tooth will be. The more delicate the saw tooth, the quicker it will dull. However, a steeper fleam angle, like 24 degrees, works great if you work primarily in soft woods free of knots. The cut will be very quick and the result smooth. For lower fleam angles, like 15 degrees, you will have an edge that is more durable, but producing a finish that is rougher. In addition, the saw will be slightly harder to push with a lower fleam angle. Finally, there is one practical consideration to keep in mind when considering fleam angle. Smaller teeth, 12 and up, are harder to file the higher the fleam angle. Since they are so small to start with, not much is gained by using a high fleam angle like 24 degrees. For ease in filing, I use a fleam angle of 15 degrees on the smaller teeth that I file.

  14. #14
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    Quote Originally Posted by lowell holmes View Post
    Looking at the saw in the saw vise, the teeth being pointed up, I laid a 4"xxs file in the gullet.

    The horizontal angle the file made with the saw plate was 80 degrees.

    The vertical angle the face of the tooth was 25 degrees from vertical.

    It's all a matter of semantics.

    The real purpose of my post was to observe that the Lie Nielsen and the old Disston saw had the same tooth geometry.

    Can you guess what my home sharpened crosscut saws will have?

    Why don't some of you make the same comparisons?

    Also, I have the Lee Valley saw file holder. The angles I posted were read from the holder. I did not estimate the geometry.
    Is it possible your file was warped? I've seen some Grobets in particular with upwards of 10 deg of twist from tip (where the guide clamps) to midpoint, and that would easily explain what you're seeing. If that's what's happening it's fairly easy to correct by only using the section of the file immediately adjacent to the guide when measuring.

    Also, did you orient the file at 90 deg to the sawplate when measuring, or did you allow it to simultaneously follow the fleam? You'll get slightly different measurements each way. The second will tell you what settings the last person to sharpen it used, as that's how the last filing pass is done.

    If you have a macro lens can you just take a picture of a short section (<=1") of the toothline from the side? Rake in particular is very easy to measure that way. Fleam is harder as it requires a shot from directly above with more creative lighting.

    25 deg of rake is incredible in the most literal sense of the word.
    Last edited by Patrick Chase; 03-07-2016 at 7:22 PM.

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    It should be noted that I am not advocating the use of fleam on backsaws up to 0.025 gauge saw plate.

    Stewie;
    Last edited by Stewie Simpson; 03-07-2016 at 7:45 PM.

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