CNC Routing routing flat sheets, longer than 96 inches in steps?

Discussion in 'Software' started by CloudDiver, Feb 10, 2018.

  1. CloudDiver
    Joined: Jun 2014
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    CloudDiver Senior Member

    I don't have my own CNC router and not much experience with larger format machines (4 x 8 ft cutting range). I have access to some really good machines to use or I can get my own, the prices are pretty fair for machines with higher quality and capability these days...

    Anyway, my question is... If you were to make panels from 4 x 8 core material that were scarfed together to make longer sheets with infused laminate on both sides; could you make large cut files for long pieces by loading the material on the table and having stop points at each scarf? The long pieces would have tabs anyway which would give the ideal stopping point as the cuter approaches the scarf, then the cut program is paused, the large sheet is slid farther across the cutting table, then the start/stop points calibrated and the cutting resumes. Is this possible or even been attempted?

    The reason I ask is because I have seen kit components cut from 4x8 stock and they must be manually scarfed afterward and taped. I just think it would be a stronger finished hull if the laminate was sliced at the limits of the 4x8 core material and there would be less taping, less labor, less fairing, stronger end product, etc. Am I crazy?
     
  2. rwatson
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    rwatson Senior Member

    "Am I crazy?"

    Yeah basically.

    The weight of even two sheets, let alone the awkwardness, resuces any gains pretty damn quickly.
     
  3. PAR
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    PAR Yacht Designer/Builder

    I've seen a robotic arm router that used a moving bed, to advance previously scarfed together material, the full length (16') of the cut. I'd imagine the same could be possible with a gantry style of CNC router. Normally the arm was a 48x96" 5 axis, but the moving table permitted much longer cuts.
     
  4. CloudDiver
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    CloudDiver Senior Member

    Yes, I've seen similar but they were multi million dollar machines. The big cabinet cutting floors in Asia have such machines. I'm sure IKEA is a pioneer in this stuff.
     
  5. CloudDiver
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    CloudDiver Senior Member

    As they say, crazier than a S#it-House Rat... Not sure if you've ever heard that one before, might be a Navy thing. Anyway, awkward yes, but heavy? I disagree but definitely awkward.
    I have a considerable amount of work to in planning out materials and cut files so its really just pondering at this stage. I think in terms of time, efficiency, and ease of transport/handling 7 assembly; just stick with 4 x 8 max cutting capability CNC router, puzzle joint the scarfs to assemble longer components. No need to re-invent the wheel.
     
  6. rwatson
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    rwatson Senior Member

    Just to chuck a little hope into the mix, I once got some CNC done on oversize plywood (2450 x 1220) on the machine of a kitchen cabinet maker.

    They had a machine that could do length up to 3600, so they could do big house cabinetry on benchtops.

    It worked a treat.
     

  7. CloudDiver
    Joined: Jun 2014
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    CloudDiver Senior Member

    Machines available to the general home craftsman are getting bigger, better, and more affordable. One of the more affordable companies in the US making CNC router 'kits' with sturdy aluminum extrusions now offers a 5 x 10 table for under $7K USD. I'm sure 12 foot lengths are not far off.
    Are you familiar with Jeff Schionning's flat panel build method for his catamaran designs? The partner firms that will cut the panel kits (Germany, South Africa, and Australia) will cut the panels in full length, panels have infused laminate on both sides and there is no tape at each scarf. The only tapes end up on the finished hull on the long horizontal seams of the panels, then additional full size laminations over that.
    I'm just exploring the possibility of making my own panel kit since a pre-cut kit is $75K USD. Their kit price includes a complete package; all panels, bulk resin/hardener, adhesive/fairing filler, and all laminate fabrics. I have a 4 x 8 table CNC router at my local Maker Club plus numerous other heavy tools. I'm also building an open source vertical cant bed CNC router. My initial intention for the 'cheap' DIV router was to make some plywood furniture and new cabinet bodies for my kitchen. This machine is a low tech, low budget solution but it makes incredibly accurate cuts for given applications. It would work perfectly for cutting flat panels of foam core and I could include more complex finger joints or puzzle joints rather than scarfs.
    Overall, I feel like I can source epoxy, laminate fabrics, consumables, and core foam for a much lower cost. The trade off is hundreds of hours of labor on my part. It would take me three to four months just to infuse 140 foam panels with a light skin on both sides. Another month to cut them all, then yet another 3 to 4 months to infuse additional laminates on the assembled panels on a 10 meter table that I would have to construct. The big question is, is all that labor and time worth the potential savings in material cost? maybe, maybe not. I'm not sure about the AUS and Germany partners, but if the Kit is cut in South Africa they specifically note that their CNC router bed is 12 meters! The build method is flexible... there is a non-profit youth sailing program in the Netherlands that is near completion of a Schionning flat panel design 13.8 meter cat. Their kit was not full length cuts, they came in stacks of 4 x 8 pre cut sheets and they used a heated press to tape and cure each vertical scarf. For the full-length kit version cut in South Africa, a couple in Virginia has just started so it will be interesting to see the difference between the two methods.
     
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