Making yer own fixed portlights

Discussion in 'Fiberglass and Composite Boat Building' started by yorktownie, Jul 11, 2008.

  1. yorktownie
    Joined: Jul 2008
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    Location: Eureka, CA

    yorktownie Junior Member

    I own a 1980 Yorktown 35 sloop with 4 8" x 18" plastic portlights. It also had 6 5" x 11" plastic portlights, but I was able to acquire replacements for these at a reasonable price (I bought 6 stainless portlights from an old Islander 36 for $200). My large plastic portlights are leaking and feeble from 30 years of sun, but the cost of metal replacements is $450 x 4 = $1800. I don't care if these portlights open or not. I want to replace them with homemade, fixed lexan portlights. The cost of 1/2" lexan is about $50 per portlight. Does anybody know how to make decent looking interior and exterior trim rings? The exterior ring should be metal. I don't know if aluminum would be adequate, but it would look OK. Stainless or bronze would be better. I don't care if the finish rings are a solid piece of metal. The problem is finding that sort of straightened "Z" shape flange you need in the proper dimensions. I don't care aesthetically if the portlights are square, as long as there is no structural reason to have them rounded off. Any ideas? Those old plastic portlights must go!
     
  2. kmorin
    Joined: Apr 2005
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    Location: Alaska

    kmorin Senior Member

    Router to the Rescue

    yorktownie,

    this explanation may not come through too well without drawings but I'm sure a 3hp wood router would make the bezels as nicely as the factory products if you make a reliable template.

    A router guide/template is just a way to use the hand held tool in a more controlled way resulting in better edges that may include profiles or bull-nose rounding.

    If you made a set of aluminum bezels and had them painted, powder coated or anodized I'm sure they'd blend into the boat's get coat/paint and last a good while.

    The port frame or through-hull portion can have one or the other of the bezels fixed- say the outside bezel in the interest of easier sealing and the inner bezel would finish the hull side ceiling material around the new port.

    The outer bezel would be welded to the tapered frame of the port's well or glass recess to allow it to be pulled against the hull side/ cabin side from inside. The inner bezel would be fitted to the smaller inside opening and cover the rough opening as well as act as a huge washer to spread the load of the fasteners clamping the hull/cabin sides together between the two bezels aiding the sealant.

    Rounding the corners isn't hard, just more metal work, and does look better, is easier to clean and won't build up organics if the boat is on a trailer under the trees.

    90% of the labor cost of custom welded products is the fitting and preparation not the actual welding time. So if you work in aluminum which you can route, cut, drill and sand and finish just like wood, you could have all the parts ready to tack-up (including a few well made fixtures to hold parts in correct orientation for tacking) and find a shop to weld the frames. Then sand completely and prepare for finishing and let a powder coater put a finish on them.

    Now they'd be ready for glass and some sealant. Sketches of this type of frame are not hard to find so even if you don't have welding equipment or experience you can do the 'wood' work to build these using router guide techniques with a few well chosen curved corners and a band saw the whole show is well within a boat carpenter's grasp.

    cheers,
     
  3. yorktownie
    Joined: Jul 2008
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    yorktownie Junior Member

    That's encouraging. I understand the design you propose, roughly, but don't have enough metal experience to be able to picture what aluminum pieces I would start with. I suppose I could take a square piece of 1/8" thick aluminum large enough to cover the porthole with a 2" lip extending beyond each side, then cut an oval hole to line up with the inner surface of the hole in the cabin side. Round off the corners and you have the piece that is visible from the exterior, the exterior finish ring. Now it gets sticky. Are you proposing to take another sheet of 1/8" aluminum, say 2" wide, and bending it into an oval to form the surface perpendicular to the exterior finish ring (the part that will form the sides of the hole), and welding that to the ext. finish ring? Then maybe welding a lip around the inside of that to butt the lexan against? Then creating an inner ring in a similar fashion for the interior? If so, I agree that's do-able. At least cutting and shaping the parts is do-able. I wonder what kind of welding costs I'm looking at here, if I bring the shaped aluminum parts to a shop. What I'm picturing would require 4 welds along the complete circumference of the opening for each portlight. That's about 150 inches of weld per portlight. If the cost of the welding plus the aluminum required per port is less than $150 then I'd consider it worth doing. That would yield a final per port cost of $200.
     
  4. kmorin
    Joined: Apr 2005
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    kmorin Senior Member

    How to Make a Port Light fFrame: Step One

    yorktownie,

    I knew this wasn't a words only type of question, so here is the first steps to the idea. Note the concentric reducer for butt weld fitting is a commonly available fitting and it is trimmed and quartered in a wood working band saw with a 6-8 teeth per inch blade and pan spray like Pam (TM) brand anti-stick spray lubing the blade.

    The dimensions are your own, of course, an these images are just the initial steps and overall concept. I'll give the outer and inner finish bezels a go and post the images with them included. This is the flat bar and plate main well or recess and rounded corners.

    The blue rounded glass flange is mainly colored to contrast the parts in these images. A router template would make these highly accurately all day long. I'd say they'd work well form 0.187" (3/16" plate) or 0.25" (1/4" plate) and a rough cut with a band saw outside and a jig saw inside would leave the router guided by a template to cut only an 1/8" perimeter. Because of the welds (to be shown later) I'd leave the cuts 90 degress and use lube on a standard carbide 2 or 3 flute straight cutter in a 1/2 shank router of 3 hp or so.

    Any shop that regularly welds aluminum (6061 alloy for the butt weld fitting [concentric reducer] and the flat bars, and 5086 or 5052 for the blue rounded glass flange) will be able to TIG weld this pretty simply. If you have to get it done by MIG (not as controllable) you'd still sand the entire frame fair- inside and outside before finishing. Print these out and show them to the welders to see if anyone has any doubts about the results???

    http://www.rjsales.com/products/buttweld/industrial/red40.html pipe fitting link for a typical supplier of these type of forged aluminum fittings.

    I'll sketch the remaining parts and show the welded versus threaded joints. Hope this helps explain how the project is almost all carpentry and only small amounts of welding?

    Cheers,
    kmorin
     

    Attached Files:

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  5. lazeyjack

    lazeyjack Guest

    you can have a pattern made on cnc, and cast in alloy, I did this, but the machining is fairly expensive for the pattern , unless you can use machine tools yourself, BUT if you have ten to do, casting is the only way really
     
  6. kmorin
    Joined: Apr 2005
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    Location: Alaska

    kmorin Senior Member

    Step Two

    yorktownie,
    here are the rest of the images to explain this, building method. Lazeyjack votes for casting the aluminum but in our neck of the woods that is prohibitively expensive, the band saw and router are more affordable for me.

    The idea here is to make the three bezels from three related but separate router templates- 1/4" Masonite hard board is very good for this application I use it all the time and the Home (train station) has it by the ton- even this far in the woods.

    All the parts are simple, all the parts are subject to templates to improve the repeatability and all will work with wood working tools so you can generate the real 'cost' of this type of port light frame in the shop at home.

    You can weld tapped blocks on the inside of the front bezel to put machine screws in from inside out to those taps. These holes have to be drilled very accurately but the bezels work as very accurate templates for this stage of work. Stove head or flat head machine screws with Tef-Gel as lube and isolation between the 316L machine screws and the aluminum will last a long time and give reliable fastening. The inside bezel would be drilled and counter sunk to accommodate this style of fastener.

    If your boating is inshore or fresh water (?) then drilling from the outside and through bolting is a very viable alternative. By using counter sunk flat head or socket recess stove head bolts you'd grip the entire cabin/hull side wall and the inner bezel would be the 'washer'. By using decorative 'acorn nut's inside the inner bezel there will only be a series of rounded SS nuts showing.

    The outer most edges of the outer and inner bezel could be beveled using a 45 degree or other angled router bit and leave a nice finish at a bevel. Bedding this frame in 5200 around the outer bezel should keep the water out and the heat in.

    If you use rubber mounted glass (inland waters not open ocean) then the rubber would mount directly in the blue glass flange. If you're offshore then make the inner bezel so it laps the blue glass flange almost totally to the inside perimeter and clamp the safety glass with this inner bezel when you glue it to the glass flange inside the hull.

    hope this makes clear my early remarks?

    cheers,
    kmorin
     

    Attached Files:

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  7. lazeyjack

    lazeyjack Guest

    pity, casting is very cost effective, you could not possibly compete machining, and you have the ability to write the files to take to the guy to machine the pattern!! once you have the patterns its cheap as chips You need to know your shrinkage, but the foundry knows this. Send your pattern here:))
    Anyways nice post K, keep it up you are rewarded in heaven
     
  8. yorktownie
    Joined: Jul 2008
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    yorktownie Junior Member

    Whoa Kmorin, you have some nice drafting program, and substantially more building savvy than I do. I'm a liveaboard with limited facilities. The idea of using a concentric reducer for butt weld fitting to create a graded flange is ingenious. I could do that. That will keep the water from pooling. I was planning to use lexan, since I can cut it. A piece of lexan clamped against the inner edge of the bezel with a rubber gasket. The inner bezel edge should be shaped to a dull knife edge. The screws clamping the lexan to the inner bezel edge will be providing all the resistance against the possibility of a wave stoving in the portlight. The screws will have to be sizable and the welds on the tapped blocks good. If one fails there will be dripping at least. It does look good. Is it possible to select the pitch of the bezel? That is, do concentric reducers for butt weld fittings come with a variety of inner/outer diameters? My cabin sides are sloped. The plastic portlights currently installed have a bezel, but the slope of the cabin side completely negates the draining effect of the lower lip, and even angles it slightly upward so that water pools on the lip. After a rain the pool empties into the cabin interior, drop by drop, leaving a sizable wet spot on the settee, and occasionally on me if I happen to be asleep there. Do you know of an ingenious method to put the curves in the trim rings? The only way that comes to mind is to start with a flat panel and cut out the shape and hole with jigsaw and drill. Seems wasteful. Lot of wasted aluminum donut holes.
     
  9. yorktownie
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    yorktownie Junior Member

    Tentative parts list for one portlight.

    external finish ring, 3/16" x 3/2", 6061 aluminum
    interior finish ring, 3/16" x 3/2", 6061 aluminum
    gasket ring, 3/16" x 3/2", 5052 aluminum
    bezel straight sections, 3/16" x 3/2", 6061 aluminum
    butt weld fitting, 3 1/2"L, lg D = 2.875, sm D = 1.315", thick = .203/.133, 40S, 6061 aluminum
    (10) tapped blocks, 3/4" x 3/4" x 1", 6061 aluminum
    lexan, 3/8" x 8" x 18"
    rubber gasket, 3/16" x 3/8"
    (10) #10 SS machine screws PH, nuts, washers
    (10) #10 SS machine screws FH, nuts, washers
     
  10. CanQua
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    CanQua Junior Member

    duplicate
     
  11. CanQua
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    CanQua Junior Member

    This link shows one table of reducers available. Not endorsing buying from the company, they just happen to have a good table.
    http://www.rjsales.com/products/buttweld/industrial/red40.html

    And I see what you mean. They were poorly designed originally causing water to pool when level due to the exterior slope of the cabin. So you definitely need to change the angle from what you've currently got. And it's only the lower wall that truly needs the slope, the rest would simply be cosmetic. As far as rounding it off as opposed to a square joint, the rounded it going to have considerably less stress than a point. Does it matter in your application? Can't tell ya. Obviously it would look better with the rounded corners. If you're already having an issue with pooling at the bottom though, you might not find a reducer that will give you a decent angle for draining. I'd recommend it for the top at least.
    What you would have to do to make up for the angle you need is to cut an angle onto the lower end of the side pieces. if square it's fairly simple. The rounded is a much more complicated piece, and you might be better off getting them welded up at the proper angle and then cutting off what you don't need of the reducer.
    If you match the needed bottom angle all the way around, you will have a smaller window area, unless you plan on cutting the hole bigger.
    Hopefully I haven't confused you too much.

    And I'd recommend Acrylic(preferably stretched) instead of Lexan. Of course it should be bedded, and any through holes should be oversized, use a bushing, and be bedded as well. You don't really want any impacts on the edge of acrylic. In the below picture you can get an idea of how we do it. And do make sure the metal you use for the bushing is compatible with the metal used for the screws. Unless you are just talking about the frame, in which case ignore the below picture.

    http://farm4.static.flickr.com/3142/2660988710_872e6c1058.jpg?v=0
     
  12. bntii
    Joined: Jun 2006
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    bntii Senior Member

    Have you considered skipping the exterior trim? Lots of installations have the poly bedded directly to the outer skin with a 1.5" overlap. The installation looks good and will provide good service. Using stem bushings on the fasteners is a good ideal to reduce the stress cracking at the holes.
    Wood interior trim is not too tough to make or vinyl 'L' roll trim can be used.
     
  13. yorktownie
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    yorktownie Junior Member

    My first thought was to skip finish rings altogether and thru-bolt some acrylic to the cabin side. That's what I'd do if I were leaving to go cruising next week. But, I don't see how a good waterproof seal could be made, at least without ugly smears of 5200 all round the perimeter. Next up the complexity scale is to do this but use an exterior trim ring, to help contain overflow sealant and improve looks, as well as support the edges of the acrylic. For that trim ring I'd want Z-formed lengths. I'd measure and cut the corners to 45 degrees then have the four pieces welded at the corners to make a 1 piece, square exterior trim ring. The ring would be thru-bolted to the cabin side and I wouldn't have to drill thru the acrylic. This would look ok, but I'd have to get custom Z-bar, and still have doubts about the ability to not leak.
    Next up the scale is kmorin's idea above, which would look and seal better. Next up is LJ's cast solution, and finally, the $450 prefab portlights (I will be doing only 4, not 10, so I doubt it would be cost-effective even if I had the skills.
     
  14. yorktownie
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    yorktownie Junior Member

    What would be the minimum recommended thickness of stretched acrylic for an 8" x 18" opening?
     

  15. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Make a wooden example of the rings you want and have the local technical school cast them out of copper. If you're lucky you can have them toss in 5% tin which will produce a nice strong bronze, maybe a touch of lead to increase it's fusibility, but it's not really that necessary.

    Another option, though not truly metal, would be to cast them in resin, but with a heavy bronze powder used as a filler. It'll look like bronze, but will be cast plastic and much lighter. Painted or clear coated a few decades of service could be expected.

    Both of the above methods could be done at home, with the resin and powder version being easier.
     
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