Bead and Cove Router Bits - Where to buy in USA?

Discussion in 'Boatbuilding' started by CatBuilder, Dec 18, 2010.

  1. CatBuilder

    CatBuilder Previous Member

    These are my thoughts as well. If you don't have a cove going all the way to the edge and you bend the joint, you introduce a defect in the surface on both sides, which just needs more fairing.

    The object here is to develop the most fair foam shapes I can so that I don't have to do a bunch of fairing later on.
     
  2. gonzo
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    gonzo Senior Member

    Each bead and cove joint is a sharp edge that needs to be sanded down or filled. The flat surfaces are not a fair curve. The convex face will be taken down so it doesn't matter. The concave face may need a bit more filling , but the center of the foam will have to be taken down. I can't see much of a problem with having a bit of an edge left on the foam. It may be better because it is stronger and not break.
     
  3. Charly
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    Charly Senior Member

    From one unfamiliar with foam :

    why not just cut a tounge and groove joint on the table saw?
     
  4. CatBuilder

    CatBuilder Previous Member

    Oh, I see what you're getting at, Gonzo. That makes sense.

    I'm trying to decide between bead and cove planking (longitudinal) and vertical foam placement.

    Vertical involves me having to build in tons of "stringers" along the stations of my mold to create a virtual "basket" to lay the foam in. Lots of work. The bead and cove longitudinal strips involve no more mold modifications, but plenty of routing and later sanding to take down highs spots.

    I'm not sure which is best for getting the job done easily and quickliy. Any thoughts, anyone?
     
  5. CatBuilder

    CatBuilder Previous Member

    It's because you are bending the foam, Charly. You are putting it on a curved surface that's the shape of the hull. It has to curve around the bilge and the hull deck joint areas. There, the tongue and groove would pop out.
     
  6. War Whoop
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    War Whoop Senior Member

    The joint can be rotated quite a bit and also never had a single problem with the edges,the trick is to push the excess adhesive out by seating the plank in the cove for gluing up the next run.

    I would setup in the afternoon before and glue a bunch of end joined planks together for the starting runs the next morning.

    The Idea of this system is to eliminate excess fixture framing and the battens.
     
  7. hoytedow
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    hoytedow Wood Butcher

    I must disagree. The part of the ellipse cut by the circular saw blade does approach circularity closely enough that the "out of roundness" is insignificant.
     
  8. gonzo
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    gonzo Senior Member

    I would like to see a circular saw that is eliptic or out of round and still can be used.
     
  9. wardd
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    wardd Senior Member

    if it cuts anything but circular the blade is not square with the table
     
  10. SamSam
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    SamSam Senior Member

    Coves made with a table saw blade are elliptical. Maybe not enough to matter.

    This is a very slight ellipse shape even though it looks round...

    [​IMG]

    This is obviously elliptical, made with the same circular sawblade but different settings...

    [​IMG]

    In both photos it can be seen that the sides of the cove have a larger radius and are flatter than the bottom.


    You only have to put stringers on the mold (every 6"?) once to make 4 sides versus all the cove and beading, glueing and fairing (inside and out) that has to be repeated 4 times.
     
  11. CatBuilder

    CatBuilder Previous Member

    Definitely, the cove or flute cut into an object coming at a saw blade diagonally will be an elliptical shape and not a circular shape:

    [​IMG]
    Elliptical Cove from pushing the foam at a table saw blade (small cylinder) at an angle.

    [​IMG]
    True semicircle cove shape.



    A saw table saw blade at any angle other than 0deg, 90deg, 180deg or 270deg will cause a section of a cylinder to be cut into the material rather than a true semicircle.

    An elliptical cove will cause problems as you rotate the bead and cove joint, since it will push the bead out of the elliptical cove (assuming the bead and the cove are both the same shape).
     
  12. CatBuilder

    CatBuilder Previous Member

    Yeah, that's what I was just thinking!

    Any other opinions out there that say I should go longitudinal vs athwartships on the foam?
     
  13. hoytedow
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    hoytedow Wood Butcher

    The blade is circular of course, but the cut-piece approaches from an angle using a special jig so the projection is elliptical, as shown by SamSam.
     
  14. SamSam
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    SamSam Senior Member

    Concerning cove and beading, isn't it better to have the radius/diameter larger than the thickness to keep the edges from being so fragile? A large radius will still allow the seam to be tight and also to rotate. The only important thing is that both the cove and bead have the same radius/diameter.
     

  15. SamSam
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    SamSam Senior Member

    One other thing is you already cut the mold stations. Will you be able to add the thickness of the stringers without effecting the dimensions of the hull?
     
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