Large scale plug.

Discussion in 'Boatbuilding' started by wojtek86, Oct 25, 2010.

  1. wojtek86
    Joined: May 2010
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    Location: CT

    wojtek86 Junior Member

    I was wondering if anyone knows anything about 3 axis machines that create large models. I am thinking about hiring a company to create a 10-15 foot model using a CNC or 3 axis machinign. Any ingo appriciated.
     
  2. apex1

    apex1 Guest

    15ft is not large for a CNC machine. There are much larger designs built by 3-5 axis CNC machines all over the world.

    DonĀ“t the yellow pages or internet search bring up some results in your area?
     
  3. duluthboats
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    duluthboats Senior Dreamer

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  4. War Whoop
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    War Whoop Senior Member


  5. Petros
    Joined: Oct 2007
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    Petros Senior Member

    I actually designed the foundation for such a machine that was larger enough to do 35 foot hulls. What do you mean by "knows anything about"?

    They are cost efficient compared to paying hand labor on building up a plug, and they can be real accurate. The accuracy not only comes from the precision of the machine, but also how it was installed. Even large footings can shift and move slightly with the loads on machine, so the design of the foundation has to be done in conjunction with the machine specifications. That said, the heavier the frame and footing usually the more accurate the outcome.

    It is also possible to have an older, less accurate and less expensive machine, make you a plug that still requires hand finish to remove the machining marks. This will save a lot of cost in exchange for some extra labor. But since the purpose of these machines is to save labor, the newer models are actually precision enough to deliver a plug almost ready for glassing to make your production mold.

    The way I understand it, you deliver the hull dimensions in some kind of compatible software format, and the plug, and they will cut it out. Some of them can do the programing for you, some will even make the plug, all for a fee. The building up of the plug is very important too, it must be strong enough to take the cutting loads without deflections on the surface. The ones I have seen (for much larger boats) were built-up plywood cross sections, well braced. than spray-in foam was used to fill out the forms, it was rough cut down to the forms (this can be done by hand, on the larger hull plugs the machine cut it down), and than some kind of plastic filler (Bondo) was used to cover the rough foam and plywood form, several inches thick. This is what is installed in the cutting machine. It is pretty heavy and rigid since it has to resist distortions and deflections to make an accurate mold.

    Except in a high production environment, it is not normal for someone to have a 10-15 foot boat hull plug made on one of these machines, though I see no reason why not other than cost. Set-up time would be almost the same as for a 30 ft hull.

    You should find someone local to do it so you can see the work being done.

    What are you making? Why pay for the plug rather than make it yourself? Did you get a price for cutting out a plug?
     
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