Cutting up the Mold. Advice?

Discussion in 'Boatbuilding' started by CatBuilder, Mar 12, 2011.

  1. CatBuilder

    CatBuilder Previous Member

    Well, I nearly have a half a hull to pull out of the mold.

    I was out in the shop today trying to figure out how to do that when it dawned on me: I can't. The shop cranes (engine hoists) I have are too low to lift out half hulls with full bulkheads attached.

    So my question is:

    What is the safest way to cut all my stations apart to pull hulls out, then put them back together to build more hulls?

    My stations look like this:

    [​IMG]

    I want to cut off all the vertical pieces on the left hand side of the picture. These pieces form the deck of the boat.

    I'd like to cut them off with very carefully fitting guide lines and some way to re-attach so as not to interrupt anything about the mold.

    This will give me an extra 33" I don't need to lift the hulls when moving the in and out, so my shop cranes will work perfectly.

    Any ideas?
     
  2. hoytedow
    Joined: Sep 2009
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    hoytedow Wood Butcher

    First, attach alignment jigs to the outside of the molds so that they will fit back together perfectly on re-assembly. Several beams bolted to "ears" on the mold should work nicely. Then, carefully cut the molds apart(not too deeply!) between the ears to separate the mold.

    Make sure the alignment tabs are oriented appropriately and cross multiple planes.
     

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  3. Tad
    Joined: Mar 2002
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    Tad Boat Designer

    Make some small plywood gusset pieces, cut them in half with a locking puzzle joint, screw them to the mold with the puzzle joint across your cut line, cut the mold off straight.......just make sure the puzzle will unlock after you cut....do some test pieces.....

    edit....ya...what Hoyte said
     
  4. CatBuilder

    CatBuilder Previous Member

    Hoyt, I'm sure your solution is the way to go. You always know how to do this stuff.

    Unfortunately, I'm mentally challenged and only understand about 3 word in your post! ;)

    I'm not sure what the following are, but will Google them today:

    *alignment jigs
    *ears
    *lengthwise or crosswise
    *multiple planes (seems to only be one plane - that of the plywood face)

    Man, am I dumb! :)

    I'll Google these up and try to figure it out.

    To answer the question about what, exactly, I'd like to cut: It would be cuts like the horizontal line in this picture.


    [​IMG]

    I would imagine I have to worry about the missing wood from the kerf as well, right? If I just put the two cut pieces back together, the round curve of the hull won't be so round anymore, by the size of the saw kerf, right?
     

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  5. CatBuilder

    CatBuilder Previous Member

    Ok, I think I got it.

    So the plates get fitted beforehand, while the plywood is still intact.

    Then, I remove the plates, make a cut between the 4 holes (2 above cut, 2 below cut).

    Now, when I go to put the mold back together, I will be able to just put those plates on to guide the pieces so they stay true.

    What about the kerf from the saw? Is there a way to handle that, or do the plates automatically handle that? When I put them back together, the cut plywood will rest only on the bolts, leaving the gap from the kerf, right?
     
  6. hoytedow
    Joined: Sep 2009
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    hoytedow Wood Butcher

    The kerf won't matter if you add butt blocks to the 2 halves to compensate so the tabs aren't closer than they were before the cut was made.
     
  7. rasorinc
    Joined: Nov 2007
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    rasorinc Senior Member

    How about putting a small hinge on the backside of the form where your straight line is and then fold the upper piece over and down. since you have a screw on each side of the cut you can maintain alignment then use a small sliver of wood(shim) to make up for the thickness of the blade. Then glu it.
     
  8. hoytedow
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    hoytedow Wood Butcher

    If you laminate a veneer to one cut face the thickness of the original cut, you won't need the butt-blocks.
     
  9. hoytedow
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    hoytedow Wood Butcher

    The hinge will be a great idea if the piece will swing out of the way enough.
     
  10. hoytedow
    Joined: Sep 2009
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    hoytedow Wood Butcher

    If you make the cuts with a Japanese saw the kerfs will be very thin.
     
  11. rasorinc
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    rasorinc Senior Member

    If no room then put a wider hinge on the side pull down the opposite way. All else will still apply.
     
  12. CatBuilder

    CatBuilder Previous Member

    The hinge won't work in this case because I have to be able to pull the whole thing away as a unit.

    A hull will be on top of those battens (blocking the batten attachment screws), so I can't remove the battens before the separation. It'll have to be able to come off in one big piece, battens still attached.
     
  13. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    You don't have to hook up your hoists at the edge of the bulkheads farthest away from the laminate. You can drill holes in the bulkheads somewhere closer to the laminate for hooking up the hoists which will give you whatever clearance you might have had before you decided the bulkheads needed to be in place before you lift the sides.

    How much weight are these things anyway? Is there no way to distribute the loads along the length of your shelter and use it to attach hoists to, to lift the pieces?

    What does the designer or any previous builders say about putting the bulkheads in at this stage of the build? I don't see where they will add any longitudinal strength unless they are also temporarily attached together longitudinally on their "free" edge. Otherwise they would just seem to be adding extraneous weight that would only stress the half panels more while moving them around and while they sit awaiting to be joined to the other half.

    On the other hand putting them in now would eliminate overhead glassing when assembling the two halves, but overhead glassing of bulkhead tab work is not all that bad.
     
  14. CatBuilder

    CatBuilder Previous Member

    Man, there are some good people on here. Thanks, Sam. I'll answer in blue below....


    Hey, anyone know the best material to use for putting in *temporary* bulkheads so I can easily remove them and also not contaminate the secondary bonding of the real bulkheads?
     

  15. hoytedow
    Joined: Sep 2009
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    hoytedow Wood Butcher

    Mdf?:)
     
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