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Thread: Table saw: Rip & Rabbet in one pass?

  1. #1
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    Table saw: Rip & Rabbet in one pass?

    Any reason this will not work?

    Mount 10" blade. Then, chippers and the outer blade from the dado set.

    I would need enough spacers between the 10" and first chipper to offset the chipper's teeth from the 10" plate.

    I am envisioning a situation where I would need a fair amount of boards - solid wood and/or ply - that are ripped to a specific width, and rabbeted. Seems like I can do it all in one pass, yes?
    When I started woodworking, I didn't know squat. I have progressed in 30 years - now I do know squat.

  2. #2
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    I would not do it for a couple of reasons

    1- Tools are dangerous enough without using them in ways they were not designed
    2- You would end up with (potentially) weird forces torquing the wood due to a through cut and a rabbet on a single pass. Does not take a lot of movement to create a violent kick back
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  3. #3
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    Not sure I see that, James.........

    The diameter difference means that the rip cut would occur ~~1" before the dado stack engages. The operations are basically sequential, not concurrent.

    Plus - how is the 10" blade functioning different that the normal 8" dado stack blade that sits in it's place? I guess it is cutting more fiber than the individual dado stack blades.......


    I can tell you this much for certain - a couple decades experience. Imagine this - you have an industrial operation making grooved 2 x 3 used for banding units of lumber [at sawmills]. You shove in a 2 x 8, and out come 3 pieces of 2 x 3 with a 3/4"W x 1/2"D groove down the middle of all three. They are split into thirds by larger diameter blades, and the outer edges are cleaned up and sized by larger diameter blades as well.

    I grant you that there are multiple components in those industrial gang-rip saws, driving the boards and acting as anti-kickback devices, but a lot of that has to do with the low-grade lumber being run {"bark and better"} at > 100 LFPM. With that low-grade, you get breaks and knots that leave disconnected pieces, and you have to control those - make sure they move to the outfeed side of the saw, rather than returning at Warp 2 to the infeed side.

    Thanks very much for your thoughts - definitely something I need to think about.
    Last edited by Kent A Bathurst; 03-26-2015 at 6:48 PM.
    When I started woodworking, I didn't know squat. I have progressed in 30 years - now I do know squat.

  4. #4
    I knew a guy who would rip drawer parts and dado them in a single pass. I don't think what you want to do is much different. A power feed would be handy though.

  5. #5
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    When doing rabbets I usually bury the dado into a sacrificial fence so the board is free and can't be trapped by the fence. I also use a feather board to keep the board pressed down against the table.

    When ripping, my splitter has pawls that prevent the board from coming back.

    I can't see combining these operations safely.... yes, in industry they have machines that take a log in one end and you get a fully assembled chair out the other, but that's a machine designed for just that purpose.

    My concern would be trapping the work piece between the blade(s) and fence. The board will have a tendency to ride up over the dado and with the rip blade installed has no where to go except a recipe for disaster (kickback!).

  6. #6
    I think it would be worth a try your outside blade should be no bigger than what you need and I definitely would use a power feeder and you have whole lot to do
    Thanks John
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  7. #7
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    It appears your going to try it. However, I agree with James.

    There is too much to go wrong. IMHO, it's not worth the risk to you nor the material.

    Remember, never stand in the path of a potential kick back.

  8. #8
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    It seems kind of limited to me - you want the rabbet at some specific depth (presumably), so your stock needs to be no more than an inch thicker than that, assuming an 8" dado and 10" rip blade. Even less when you leave room for the rip teeth to clear the top surface.

    Mike

  9. #9
    The teeth on the chippers are wider than the blade plate. So you will need some sort of spacer between the last chipper and the 10" blade to prevent crushing the chipper's teeth into the 10" blade, and also bending the 10" blade plate somewhat.

    In doing dados I like to apply some extra downward pressure over the dado stack, to make sure my depth is consistent. But you can't get too close because you have a 10" blade ripping through.

    It seems like a tradeoff. You're saving a step, but possibly getting less than consistent dado depth.

  10. #10
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    Quote Originally Posted by Phil Thien View Post
    The teeth on the chippers are wider than the blade plate. So you will need some sort of spacer between the last chipper and the 10" blade to prevent crushing the chipper's teeth into the 10" blade, and also bending the 10" blade plate somewhat.

    Yeah - I noted that in me OP

    Quote Originally Posted by Phil Thien View Post
    In doing dados I like to apply some extra downward pressure over the dado stack, to make sure my depth is consistent. But you can't get too close because you have a 10" blade ripping through.

    It seems like a tradeoff. You're saving a step, but possibly getting less than consistent dado depth.
    There's a good point - maybe use a block of wood to offset a vertical featherboard so it is out near the dado................
    When I started woodworking, I didn't know squat. I have progressed in 30 years - now I do know squat.

  11. #11
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    Quote Originally Posted by lowell holmes View Post
    It appears your going to try it. However, I agree with James.

    There is too much to go wrong. IMHO, it's not worth the risk to you nor the material.

    Remember, never stand in the path of a potential kick back.
    All good points - thanks. Not sure that this project will ever come to pass - was just letting my mind roam through the materials/machining steps.
    When I started woodworking, I didn't know squat. I have progressed in 30 years - now I do know squat.

  12. #12
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    Quote Originally Posted by Kent A Bathurst View Post
    Not sure I see that, James.........

    The diameter difference means that the rip cut would occur ~~1" before the dado stack engages. The operations are basically sequential, not concurrent.

    Plus - how is the 10" blade functioning different that the normal 8" dado stack blade that sits in it's place? I guess it is cutting more fiber than the individual dado stack blades.......
    Kent,
    The cuts will be simultaneous, just maybe not in the same point on the board. For the majority of the cut both the 10 in blade and the dado stack will be engaged.

    The 10in blade will put a different force on the board than the 8 in chippers and blade. It may not matter, but it does not take much to cause a kick back
    America is great because she is good. If America ceases to be good, America will cease to be great.
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    C. S. Lewis

  13. #13
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    How much are you ripping off? My first though was...shaper. We used to use a 30HP machine to do something like this en masse, I'm not saying it can't be done with a TS, I do wonder what surface quality do you require when its finished? Its an interesting idea. What is the product?
    "A good miter set up is like yoga pants: it makes everyone's butts look good." Prashun Patel

  14. #14
    Seems to me that it would work. Give it a try and let us know how it come out. Just be very careful the first time you try it - maybe make a lesser cut and work up to what you really want to do.

    Mike

    [Regarding consistent depth, that's always a problem with dado cutters. You have to keep pressure down on the work to make sure it doesn't rise up over the blade and cut to a lesser depth. I'm not a big fan of dados, grooves or rabbet on the table saw with a dado cutter for that reason.]
    Last edited by Mike Henderson; 03-26-2015 at 11:47 PM.
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  15. #15
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    Quote Originally Posted by Mike Henderson View Post
    .........Regarding consistent depth, that's always a problem with dado cutters. You have to keep pressure down on the work to make sure it doesn't rise up over the blade and cut to a lesser depth......
    Very true.

    Normally, my rabbet edge would be cut against a zero-clearance fence, with a vertical featherboard above it to ensure correct & consistent depth.

    But, with this scheme, the rabbet edge would be away from the fence, and I would need to rig a featherboard out there - fingers will not do it with the larger dia rip saw on the far edge.
    When I started woodworking, I didn't know squat. I have progressed in 30 years - now I do know squat.

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