New Design Temporary Female Mold Build Help...

Discussion in 'Fiberglass and Composite Boat Building' started by bjdbowman, Feb 12, 2018.

  1. bjdbowman
    Joined: Apr 2017
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    Location: Florida

    bjdbowman Junior Member

    Yes... the bigest segment/part would be 8'x12'x4'. Composite work done in the AC garage.
     
  2. rob denney
    Joined: Feb 2005
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    rob denney Senior Member

    Vacuum pumps are a couple of hundred bucks. Choose your design carefully and there is no cnc cutting required.
    The Easy Composites videos are excellent, but there is a vast amount more that can be achieved, at lower cost, with Intelligent Infusion.
    It is far easier to build the components in a mould.
    There are 2 types of join. Self aligning and non self aligning.
    The former are easy to include in the infusion and only require gluing. Takes minutes. These are used in Intelligent Infusion.
    The latter have to be aligned, filled, filletted, tabbed and faired. These are used in flat panel boat building. Takes days.

    Only if you want to minimise labour, materials and frustration.

    Be careful. Plywood compounds (stretches) a fair bit, glass barely at all. Unless all surfaces are conic, the glass panel will not fit and may crease or require cuts. The glass panels will be a lot stiffer than the ply ones so may not twist at the bows.
    Multi chine is neither "simple not speedy". It is an absurd amount of work to build the panels (5 per hull), join them (6 x the length of the hull on your knees filletting and tabbing, then fairing them. Repeated on the outside, then again for the other hull. Then inserting bulkheads which need to be individually fitted, trimmed and aligned before another ~100 metres of filletting and tabbing. The end result is a hull with a little more draft and a little less wetted surface than a sharpie type hull.

    It is far easier to build the hull side and half the deck and bottom in one shot, then repeat it for the other side. ie 4 full length pieces for both hulls and decks vs 12 pieces for the double chine hulls. 24 half length pieces if you are going to build them in the garage.

    Save yourself a huge amount of work by setting up the mould in a tent and infuse it all in one shot. Put the first half outside, infuse the other, then add the fit out (built on a table in the garage) and add the other half. You will spend less time in the tent than you will if you build the pieces in the garage and assemble them in the tent. Not only less time, but most of it will be doing easy work like cutting glass and foam.

    You get a much better idea of the size and how it all fits together if you have a full length mould of half the hull and decks. Could even tip it on it's side and walk around inside it, if you really want to.

    I disagree. This harryproa half hull and decks was infused above the Arctic Circle by 2 guys who had never built a boat before. It has curved sections, which makes it much harder than the straights used in Intelligent Infusion. They then built 3 others halves, plus many smaller pieces, without any problems. Note the simplicity of the plumbing. The infusion is 20m/66' long, 2.4m/8' wide and 1m/3' high. The shed is not much bigger.

    Screen Shot 2018-02-26 at 9.21.22 PM.png Screen Shot 2018-02-26 at 9.22.02 PM.png Screen Shot 2018-02-26 at 9.22.28 PM.png Screen Shot 2018-02-26 at 9.22.52 PM.png
    There are more pictures at Custom 20m/65′ – NORWAY – Harryproa http://harryproa.com/?p=726 There are a number of others with similar experiences.
    The great thing about infusion is that you make sure everything is right before you mix resin. There is plenty of time to get the cloth, spacers, core, rebates, inserts and plumbing in the right place, then seal the bag.
    The things that can go wrong are:
    Lack of vacuum. This is tested before you start by clamping the hose as per the video.
    Bridging in the corners. This is not fatal, 'just' uses more resin, but is easy to see before you start and less of a problem with Intelligent Infusion because of the location of the core and cloth joins.
    Poorly measured or mixed resin. There is nothing else to do apart from watching the resin travel, drinking tea and telling everyone "Wow, this beats the hell out of wet laminating!" so plenty of time to get resin measured and mixed.

    I am tight fisted, lazy and usually on a strict time limit (the wife needs the garage back), so take all the short cuts I can think of. The worst I have achieved is some unwet out cloth on the mould side due to lack of vacuum (the dry bits were bagged and infused individually after demoulding) and some pretty awful looking bridging which consumed half a litre of resin more than it should have. This is about the amount you will waste in brushes, rollers and drips on the floor each time you wet laminate.

    Having said this, you need to be confident (or Norwegian ;-)) to tackle the big jobs first. There are plenty of small jobs that can be done, plus a load of trial pieces in the plans to build your competence and experience.
     
  3. bjdbowman
    Joined: Apr 2017
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    Location: Florida

    bjdbowman Junior Member


    Nicely done my friend... you make it sound so easy... You guys have me convinced that the infusion method is the way to go.

    Okay, so I will move towards this end with the thought that materials choices and panel design are the most important factors in the build process. I don't think that I am capable of a Harryproa type project, so I plan on keeping the parts simple and as easy as possible to manage and infuse. Segmented construction in a small footprint with female molds. This way I can use the Gel-coat and then do the lay-up right in the mold with the added benefit of the infusion method.

    Thanks again... Now on to the question at hand... How to release the part from the mold? I am going to try the drywall mud for the fairing of a female mold and then try a coat or two of good wax and then two coats of PVA. I will do an experiment this week and let you know how it comes out.

    Thanks,
     
  4. rob denney
    Joined: Feb 2005
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    rob denney Senior Member

    You can lead a horse to water......

    Mould release is covered in an earlier post. As is the folly of gel coat. What we haven't mentioned is that dry wall mud is probably not airtight, so the mould including the vac flange needs to be, before the drywall is added. No idea of the surface qualities of drywall plus 2 x wax and pva, but suspect it will stick to the gel better than it will to the mould, and the gel will be pretty ordinary even if it doesn't.
    Epoxy won't stick to gel coat, so use long cure time vinylester. As Fallguy said, start racking up the brownie points with wife and neighbours, because it stinks. It also burns like petrol and in enclosed spaces (like garages) can cause dizziness etc, so be sensible. Ve can be tricky stuff to use, so read and obey the instructions and ensure it is not and does not get old. Do not leave recently cured Ve mouldings in the sun or they will warp. Leave them for at least 10 x 25C days before epoxy gluing.

    Good luck with your build, think of us while you are doing all that extra work.
     

  5. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    No. The fairing of the mould is easiest to do with some cabosil, balloons, and your choice of glues. I would use epoxy-you can use some fast and be fairing by day's end. The compound oftentimes is also keeping the mould in the proper shape - drywall mud will not provide any strength for the mould and will readily crack. You'll see in this beaching keel mould, there is a keeper in place prior to installing the fillets. The fillets actually help the mould retain its shape-consider them a structural element of the mould, per se. There is also fiberglass skin on the reverse side of this mould. But joint compound would be a major no - no. It shrinks a bunch, cracks easily..all bad for mould making. The non shrinking versions are hard to sand, etc.. IMG_4220.JPG

    IMG_4220.JPG
     
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