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Thread: Flat Grind Rip Blades

  1. #1
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    Flat Grind Rip Blades

    Hey all,

    I'm trying to do some bridle joints, and I need to buy a flat grind blade. Would you get one with more or fewer teeth for this job? Seems like a box joint jig has more teeth, a rip blade has fewer. Any reason to choose one over the other?

    I've used mine to make half lap joints for internal frames in cabinets.
    Last edited by Lee Schierer; 06-23-2022 at 8:45 PM.

  2. #2
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    Box joint cuts are primarily crosscut operations so ore teeth = cleaner cut. Bridle joints are primarily rip cut operations so a 24 - 30 tooth FTG should do you fine. That said, I use a 50 tooth ATB+raker that I had made. These are often called 'groovers' (Amana 61368 for example) and are readily available. I just wanted one with an 1/8" kerf so I had it made special. For what you are doing any quality 24T FTG should do you.

    P.s. I've never had a bridle joint sag. My favorite door frame joint.
    Take me to the hotel - Baggage gone, oh well . . .

  3. #3
    Why not a dado? For such a small piece as a bridle joint, it should work fine. You can also use a spacer (same size as the tenon) between the two outside cutters and cut both sides of the tenon in one pass. This is assuming you're using a tenon jig on the ts.

  4. #4
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    Quote Originally Posted by glenn bradley View Post
    Box joint cuts are primarily crosscut operations so ore teeth = cleaner cut. Bridle joints are primarily rip cut operations
    Isn't that backwards, Glenn? Box = rip; bridle = cross
    --

    The most expensive tool is the one you buy "cheaply" and often...

  5. #5
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    How big are the bridle joints? I've made large cabinet doors with them, so the joint was 3"x3". A bandsaw was far less scary than a tablesaw.

  6. #6
    Flat top blades with over 30T are going to be pricey.

    Good justification for a dado set.

  7. #7
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    Quote Originally Posted by Jim Becker View Post
    Isn't that backwards, Glenn? Box = rip; bridle = cross
    OMG!!! More coffee - stat! Thank you Jim .
    Take me to the hotel - Baggage gone, oh well . . .

  8. #8
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    The Dewalt dado set cuts nice flat bottoms with sharp, square corners. I bought it for when I didn't want to use a "good" set, but it's surprised me at how good it is.

  9. #9
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    Its funny; I finally decided last night to cut it with the ATB blade that was available in the public shop I'm working in. I didn't use the 8" dado blade because it didn't cut deep enough.

    Except, for a bunch of reasons (which ended up in a few trashed pieces of this box top), I was wrong and probably could have used the dado stack all along. I ask you all not to judge me for being an idiot.

  10. #10
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    Quote Originally Posted by glenn bradley View Post
    OMG!!! More coffee - stat! Thank you Jim .
    Bridle and box joints are both rip functions as you are pulling long grain fibres out of the wood. Dovetails are also rip functions when sawing.

    To visualize this, imagine a board as a bundle of long straws, when ripping you are cutting along the same axis as the straw’s long dimension, whether the bundle of straws is laying on the table, or standing vertically.


    Regards, Rod
    Last edited by Rod Sheridan; 06-23-2022 at 8:10 PM.

  11. #11
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    The Freud Glueline rip blade has flat top teeth and TCG and is reasonably priced. Half of the teeth are flat top half are TCG. It gives a nice flat bottom kerf and a smooth sidewall cut.
    glue.jpg
    Lee Schierer
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  12. #12
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    Quote Originally Posted by John Kananis View Post
    Why not a dado? For such a small piece as a bridle joint, it should work fine. You can also use a spacer (same size as the tenon) between the two outside cutters and cut both sides of the tenon in one pass. This is assuming you're using a tenon jig on the ts.
    A dado would be fine with a dado set. My outside dado blades have tiny ears on the outside edge of the main blades. These leave a little groove. That wouldn't matter on a dado unless the ends are visible; it will be visible on something like a bridle joint.

  13. #13
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    Quote Originally Posted by Rod Sheridan View Post
    Bridle and box joints are both rip functions as you are pulling long grain fibres out of the wood. Dovetails are also rip functions when sawing.

    To visualize this, imagine a board as a bundle of long straws, when ripping you are cutting along the same axis as the straw’s long dimension, whether the bundle of straws is laying on the table, or standing vertically.


    Regards, Rod
    Good point...my eyes were reading "bridle" but seeing "lap"...oy! Of course that applies to the "mortise" part of the bridle. The tongue is often cross-cut for convenience, but it depends upon the size of the components, too. Lots of ways to fry that fish!
    --

    The most expensive tool is the one you buy "cheaply" and often...

  14. #14
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    The Freud Glue-Line Rip blade has served me well for years. I don't remember but I think it is a 40-tooth blade, flat top grind. I use the full kerf version (.125). It cuts flat bottom kerfs and works well for cutting small drawer bottom grooves and mitered corners for splines.

  15. #15
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    I went with a Freud LM72R010 10-Inch 24 Tooth FTG Rip blade for flat bottom kerfs. I mostly use it for cutting spline grooves.
    Sharp solves all manner of problems.

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