making custom portholes

Discussion in 'Fiberglass and Composite Boat Building' started by robwilk37, Jul 26, 2013.

  1. robwilk37
    Joined: Nov 2010
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    Location: san diego

    robwilk37 Senior Member

    so after years of searching for used oval portholes with no luck, ive decided to take a whack at fabbing my own. the idea is to lay-up the oval section in glass/epoxy/graphite, cut to length at the appropriate angle for drainage, and epoxy in place through the house sides. next, cast the inside ring with hinge/dog attachments via lost wax, and the same for the lens frame. the hinge is dead simple, the dogs can be made from off the shelf eye bolts and wing nuts. laminated safety glass finishes them off. the inner casting would through bolt to an exterior stainless trim ring, although with the oval section being epoxied in it would only serve as a backing plate for the interior casting.

    i need a total of 14, 7 pairs of decreasing sizes. new found metals, although beautifully crafted, are way outside my budget. ive got access to a 2900deg kiln, lost wax is fairly straight forward, plaster/green sand is cheap etc...

    so, questions. silly bronze, bronze, stainless, naval brass? anyone done their own castings? any one got a source for scrap or ingots?

    thanks in advance.
     
  2. gonzo
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    gonzo Senior Member

  3. PAR
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    PAR Yacht Designer/Builder

    I've done this a few times. I have a buddy in Tennessee that has forge and he can cast up most things, but it's not cheap.

    I've made epoxy castings that look just like the bronze, but are home made. Essentially, you make a wooden mockup of what you want, which is a couple of rings, one with a rabbit to hold the glass. These are then molded in plaster and the wooden plugs removed. Next is the epoxy, which is heavy filled with bronze dust. The result looks right and with a good clear coat works well. The last set I made I used a two stage pour, the first was a bronze dust filler, but followed with a milled fiber pour to provide a bit more strength, as I've had cast hinge points break on previous models. The hinges could be applied afterward, which would solve this issue. The bronze dust is available in a few colors and it's about 70% to 80% by volume in the epoxy.
     
  4. robwilk37
    Joined: Nov 2010
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    robwilk37 Senior Member

    yes, thanks. ive seen those sites and many others. $500 X 14 plus shipping is out of the question though, and im looking for a tapered oval, like hans uses. seems most of the money is in the labor and not materials. labor i can readily supply, and lost wax has been around 4000+ years so doesnt seem like it would be too complicated. plenty of utube tutorials as well. just wondering about materials...

    and yes considered epoxy/dust. also CNC out of G10 (ive got many large blocks) but casting would be more fun and the gleam of bright bronze is lovely...
     
  5. gonzo
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    gonzo Senior Member

    Bronze is fairly easy to come by. Have you tried the local salvage/recycling yards? They usually sell the metal at a better price than retail. Also, you may consider fabricating them instead of casting.
     
  6. robwilk37
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    robwilk37 Senior Member

    yeah, bronze is available. with copper being at an all time high though its not cheap. the problem with the recyclers if what alloy am i getting... but since the parts are interior i dont know if i need to worry about the silica. for that matter brass might serve...
     
  7. michael pierzga
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    michael pierzga Senior Member

    A few years ago Woodenboat mag did a special on casting bronze boat fittings. You might search it out for tips.
     

  8. robwilk37
    Joined: Nov 2010
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    robwilk37 Senior Member

    ive got these old lewmar 55 3-speed winches, non self tailers. chrome over bronze. cant sell em, cant give em away. it would be a shame, but im thinking of cutting them up for scrap. im assuming they are silicon bronze but dont know that for a fact... any ideas? id grind the chrome off of course.
     

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