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Thread: Can't get sharpening angle right

  1. #1

    Can't get sharpening angle right

    All, I'm struggling to learn to sharpen my chisels.

    I purchased GREBSTK 4PCS Professional Wood Chisel Tool Sets Sturdy Chrome Vanadium Steel Chisel, 1/4 inch,1/2 inch,3/4 inch,1 inch which are supposed to have a Sharpening angle of 25 degrees.

    I have tried everything from wet stones, to diamond plates and now trying the scary sharp float glass + sandpaper solution.

    I have a sled that allows me to set the angle accurately. I set that to 25 degrees, but only the very back top the chisel blade is making contact.

    https://www.dropbox.com/s/7mrfhpp939...21.00.jpg?dl=0

    I increased the angle to 30 deg and that helped a bit, but I'm nervous to get off the factory spec.

    How do I get the front of the blade to contact? I know I could keep sharpening for a _long_ time and the chisel would eventually sharpen at that angle.

    Thanks for any help.

    Tim

  2. #2
    Join Date
    Mar 2019
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    Los Angeles, California
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    824
    1. Put it on a wheel, like a Rikon, and grind it to the proper angle; or

    2. Match the existing angle, whatever that is. Use an angle finder or one of those small brass circular notched angled finders to figure out the existing angle; or

    3. If you are using scary sharp, try some 80g paper; or

    4. Make a wood jig that looks like a a drawer handle to bridge a belt sander and rough sand the chisel to something equivalent to 25 degrees.
    Regards,

    Tom

  3. #3
    so I could find the angle -- but it seems like I should just grind it to the right angle and work with that.

  4. #4
    Join Date
    Oct 2014
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    Pittsburgh, PA
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    Quote Originally Posted by Tim Booher View Post
    All, I'm struggling to learn to sharpen my chisels.

    I purchased GREBSTK 4PCS Professional Wood Chisel Tool Sets Sturdy Chrome Vanadium Steel Chisel, 1/4 inch,1/2 inch,3/4 inch,1 inch which are supposed to have a Sharpening angle of 25 degrees.


    I have tried everything from wet stones, to diamond plates and now trying the scary sharp float glass + sandpaper solution.

    I have a sled that allows me to set the angle accurately. I set that to 25 degrees, but only the very back top the chisel blade is making contact.

    https://www.dropbox.com/s/7mrfhpp939...21.00.jpg?dl=0

    I increased the angle to 30 deg and that helped a bit, but I'm nervous to get off the factory spec.

    How do I get the front of the blade to contact? I know I could keep sharpening for a _long_ time and the chisel would eventually sharpen at that angle.

    Thanks for any help.

    Tim
    https://youtu.be/GN4yr7vp4I4

    I'd recommend watching some additional videos on sharpening. There are a million. But one key is understanding the idea of "primary" and "secondary" bevel. The factory bevel is probably somewhere around 25 degrees (though the exact number isn't necessarily important). The secondary bevel is what actually does the cutting (and more specifically, the edge between the secondary bevel and the back, both of which need to be flat, is what does the cutting), and many people will set that around 30 degrees.

    If you don't use a secondary bevel, then yes, you have to get the whole primary bevel honed evenly. Not just on setup, but every time you sharpen. That's why the secondary bevel is helpful, as you only have to hone the first few millimeters of the blade. If you set it up this way, then you'll only have to regrind the primary bevel if you damage/chip the edge significantly and have to grind back the tip to repair it.
    Last edited by Patrick Varley; 05-17-2023 at 1:30 PM.

  5. #5
    Join Date
    Sep 2013
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    Wayland, MA
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    3,450
    Start on a powered grinder or sander to set the starting angle (a slightly concave cut will make your hand sharpening easier as only the front and back edges of the bevel will contact the stone. Yes, you just need to remove enough material to establish the primary bevel. It will take a long time by hand, be pretty quick on the grinder. Once that's done resharpening will be fairly quick work.

    Only some chrome vanadium steels are high speed steels with heat resistance sufficient to turn red without losing temper so I'd treat them as if they are not, keeping them cool enough during grinding to avoid bluing of the edge.

    A jig like the Veritas one makes keeping a constant angle much easier when hand sharpening.

  6. #6
    Join Date
    Dec 2016
    Location
    Houston, TX
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    The chisel looks to be a hollow grind, ground on a wheel. When you then sharpen the chisel on a flat stone the edge will only contact the stone at the top and the bottom. The chisel is sharp in your pic, just use it, the cutting edge is only where the two surfaces meet, not all the way up the slope. After you use the chisel and sharpen it a few time the two contact points will get closer and closer until they meet and you have a flat surface, that will not make the chisel any sharper.

  7. #7
    Quote Originally Posted by Tim Booher View Post

    I have a sled that allows me to set the angle accurately. I set that to 25 degrees, but only the very back top the chisel blade is making contact.

    https://www.dropbox.com/s/7mrfhpp939...21.00.jpg?dl=0

    I increased the angle to 30 deg and that helped a bit, but I'm nervous to get off the factory spec.

    How do I get the front of the blade to contact? I know I could keep sharpening for a _long_ time and the chisel would eventually sharpen at that angle.

    Thanks for any help.

    Tim
    Yes, the top of the bevel will be the only part touching until you grind enough away to get down to 25 degrees, then the front of the blade will be making contact,
    Keep in mind, you're lowering the angle, you have to remove some material to get there.
    Don't worry about the factory specs, they're your chisels, sharpen them to what ever angle works for you.
    As others have said, maybe take it to a grinder to remove the bulk before using your sled or sharpening system of choice.

  8. #8
    Join Date
    Mar 2016
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    Millstone, NJ
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    1,159
    Using a jig, I think, you will have to extend it every so often as you cut through the old bevel or your angle will get steeper as you go.
    I never had to establish a new primary bevel before

    I used the jig my first 2 times but then switched to doing it freehand on water stones.

  9. #9
    Join Date
    Sep 2016
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    Modesto, CA, USA
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    If the tool has water on it you are in no danger of overheating the steel. Very slight chance of overheating just the tip if you get too aggressive. If the working edge stops steamimg it is dry, quench in water and continue.
    Rock cutting grinders sit a pan of water with a sponge touching the underside of the wheel.
    Bill D

  10. #10
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    Location
    Peoria, IL
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    Get a good grinder set up and it will only take 3 minutes to grind and then less than 3 minutes on grinding stones.

  11. #11
    Join Date
    Feb 2004
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    Perth, Australia
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    Quote Originally Posted by Tim Booher View Post
    All, I'm struggling to learn to sharpen my chisels.

    I purchased GREBSTK 4PCS Professional Wood Chisel Tool Sets Sturdy Chrome Vanadium Steel Chisel, 1/4 inch,1/2 inch,3/4 inch,1 inch which are supposed to have a Sharpening angle of 25 degrees.

    I have tried everything from wet stones, to diamond plates and now trying the scary sharp float glass + sandpaper solution.

    I have a sled that allows me to set the angle accurately. I set that to 25 degrees, but only the very back top the chisel blade is making contact.

    https://www.dropbox.com/s/7mrfhpp939...21.00.jpg?dl=0

    I increased the angle to 30 deg and that helped a bit, but I'm nervous to get off the factory spec.

    How do I get the front of the blade to contact? I know I could keep sharpening for a _long_ time and the chisel would eventually sharpen at that angle.

    Thanks for any help.

    Tim
    Tim, even the best new chisels arrive as a kit. In addition to preparing the primary bevel and then sharpening the edge, you also need to ensure that the back of the blade is coplanar (it must not have high spots) and the back of the bevel is polished (1” is enough).

    Further, if you plan to use a mallet or hammer to strike the handle, the blade edge needs to be tough enough to handle the forces on it. This translates into a bevel of 30-35 degrees. 25 degrees is too low. It will chip or fold.

    With chrome vanadium steel, which is hardened by the addition of chrome, you need a strategy to sharpen. You cannot hone the full face - it will be arduous. Either you hollow grind the face (my preference, but I freehand blades) or you use a honing guide to create a small secondary bevel. I am not sure what you mean by “sled”.

    If the heel of the bevel is touching, either the original bevel is not 25 degrees, or the guided angle is lower than 25 degrees. In any event, you want 30 degrees. Look up “secondary bevel”. Search for honing guides (Veritas offer a few types) and an “angle setting board”.

    Regards from Perth

    Derek

  12. #12
    Join Date
    Feb 2023
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    Worcester, MA
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    First, I would measure the chisel angle with an angle finder. Just because the vendor says it's 25 Deg, that doesn't necessarily make it so. If the chisel is on spec, then check your sharpening guide. Is it really 25 Deg?

  13. #13
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    I increased the angle to 30 deg and that helped a bit, but I'm nervous to get off the factory spec.
    Quote Originally Posted by Tim Booher View Post
    so I could find the angle -- but it seems like I should just grind it to the right angle and work with that.
    Tim, don't worry about the factory spec.

    Don't worry about the "right angle."

    There is no "correct angle."

    It might help if you included your location in your profile. You may live near another member who would be willing to help you in person.

    My chisels are set up at at a few different angles. (surely some here think me a nut case)

    For paring, a shallow angle, 15-20, works well for me. It is also likely to need refreshing more often.

    For chopping 30 works fine.

    Most of my chisels have a single bevel. My mortise chisels may have a secondary bevel.

    Many have suggested using equipment you may not have.

    Don't run out and buy something just yet.

    One way to use what you currently have is instead of trying to set the chisel to a particular angle try setting it to the angle it already has.

    I've done this by using a flat surface and holding the chisel's bevel flat on the surface. Then positioning the guide (sled holder whatever) to hold the chisel at that angle.

    The goal is to remove as little metal as needed to get a sharp edge.

    Later when you have more experience you can work on getting exact angles or regrinding the angle.

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  14. #14
    My 'practice' set of chisels from years ago were the blue Marples chisels. They came with a carpenter's bevel on them, close to 40 or 45 degrees, so very blunt. I did grind them down to 25 for the primary bevel and then 30 for the secondary bevel. That greatly improved the cutting ability. My guess is that the present angle on your chisels is more the carpenter's bevel, and not the fine woodworking bevel. Not sure if you can measure the present angle or not. A grinder can be a huge help in establishing the primary bevel. After that, maintaining that primary bevel is much more simple. You can do that all by hand, but you will need a lot of time and elbow grease....

    robo hippy

  15. #15
    Quote Originally Posted by Jim Koepke View Post
    Tim, don't worry about the factory spec.

    Don't worry about the "right angle."

    There is no "correct angle."

    It might help if you included your location in your profile. You may live near another member who would be willing to help you in person.

    My chisels are set up at at a few different angles. (surely some here think me a nut case)

    For paring, a shallow angle, 15-20, works well for me. It is also likely to need refreshing more often.

    For chopping 30 works fine.

    Most of my chisels have a single bevel. My mortise chisels may have a secondary bevel.

    Many have suggested using equipment you may not have.

    Don't run out and buy something just yet.

    One way to use what you currently have is instead of trying to set the chisel to a particular angle try setting it to the angle it already has.

    I've done this by using a flat surface and holding the chisel's bevel flat on the surface. Then positioning the guide (sled holder whatever) to hold the chisel at that angle.

    The goal is to remove as little metal as needed to get a sharp edge.

    Later when you have more experience you can work on getting exact angles or regrinding the angle.

    jtk
    I totally agree and put myself in the same camp. 20 for paring, 25 for general and 30 for chopping or repeated striking.
    Different chisels and their uses require different cutting angles to be the most efficient.

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