Reinforcing plastic

Discussion in 'Construction' started by Kotori87, Feb 4, 2007.

  1. Kotori87

    Kotori87 Well-Known Member

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    Hey, folks. I bought a plastic 1:142 scale ship for conversion to RC combat. I know the hull is not strong enough to hold up under fire, and I intend to reinforce it with fiberglass. Trouble is, I'm not sure how to go about it.

    I already have some good epoxy, but I'm not sure what weight and weave of fiberglass to use. Also, my brother Eric says to fiberglass the outside while I want to fiberglass the inside. What do you guys think? The hull needs to be strong enough to hold up under Big Gun fire at close range, but not so heavy that I cannot install the running gear. Also, if the fiberglass is on the inside, how will the plastic hold up under fire?

    The model is the Revell North Sea Trawler, about 14" long 2" wide, and takes approx 7 oz weight to float at waterline.
     
  2. Tugboat

    Tugboat Facilitator RCWC Staff Admiral (Supporter)

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    I tested a submarine model that I intended to use in the same manner. My BB gun went right through it, and cracked the plastic along the length of the hull to boot. This was unreinforced plastic, though. I understand the desire to put the 'glass inside, as that's what I thought about when I was looking at the North Sea Trawler in the hobby store. I'm not sure that it's the best idea, though as the plastic is still vulnerable. Also, it's not like anyone will be able to see the hull, regardless of which side the fiberglass is on, because it'll be sheeted anyway. My advice is to glass the outside, with the NAPA fiberglass. Good and heavy, soaks resin/epoxy well, and it's very flexible. 2 or 3 layers of it, too.

    They're nice looking models, I'd do one if I wasn't already trying to get Gneisenau ready for the spring break battle, and T-103 and Komet ready for Nats, and all the plugs ready for... lol. I think my next new ship will be a ways off.
     
  3. Robert Clarke

    Robert Clarke Member

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    Do both, and do it before you cut the panels.
    (I saw that model, I had it in my hand, but I said nawww......sigh)
     
  4. Kotori87

    Kotori87 Well-Known Member

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    Robert, why do you recommend glassing both sides? Will the plastic still crack under fire if its fiberglassed on the outside?
     
  5. JustinScott

    JustinScott Well-Known Member

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    There might be something to the compression "bowing out" the inside of the model on impact & cracking/shattering the plastic. However, does it matter? Not really. The resin will hold it shape & probably the plastic shards as well.

    I would probably wrestle with the idea of using the plastic model as a "plug" & creating an entirely fiberglass ship. Close call.
     
  6. Kotori87

    Kotori87 Well-Known Member

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    I did get two of the kit, specifically so I can make a plug from the second, if the first works well. The only reason I would worry about plastic cracking on the inside is that components would be mounted to the plastic. It wouldn't do to have the ship get shot and the motor break loose. What weight of glass cloth would you recommend?
     
  7. JustinScott

    JustinScott Well-Known Member

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    I use (always have used) fleece instead of fiberglass mat. It stretches better & is much much thicker. I figure it works great for car stereo subwoofers, it is more than enought for model boats. I usually put a few layers of automotive (boat) fiberglass cloth on the outside (but for no real reason). I also make the boat hull a (quite) a bit thicker than most.
     
  8. JustinScott

    JustinScott Well-Known Member

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    Ohh.. I'd also attach everything to the fiberglass not the plastic, that would save the problem you are worried about. Just make the glass thick enough to "embed" a nut in it.
     
  9. Tugboat

    Tugboat Facilitator RCWC Staff Admiral (Supporter)

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    I'm with Justin's original suggestion... Just go ahead and make a plug from it. Avoid all the ifs and maybes (on the plastic shards) and make a fiberglass hull.
     
  10. Kotori87

    Kotori87 Well-Known Member

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    I think I will. Where do you get fleece? Also, what should the plug be made of? (I've seen some fiberglass and others RTV Silicone)

    Apparently there was a floating lighthouse with a hull similar to the Arctic Corsair. After I make the mold I'll make one hull for the cargo boat, then make a few more (and fill them with foam) for buoys to mark the convoy route.
     
  11. Tugboat

    Tugboat Facilitator RCWC Staff Admiral (Supporter)

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    The idea is to use the plastic hull itself as a plug. Either make a fiberglass mold of the plug and make hulls from the mold, or use the plastic hull as a negative mold... put a layer of cling wrap on the plastic hull and drape fiberglass over that to make hulls. They won't be as pretty (no molded gel coat) but it would be faster and less painful to do. The ship would be slightly bigger than your original form (plastic hull), but for making a generic freighter hull, that's ok.
     
  12. JustinScott

    JustinScott Well-Known Member

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    Fleece is available at JoAnn Fabric, etc. Sewing shops.



    Actually, what I'd do is:

    Spray PAM (cooking spray) ALLLL OVER the plastic model so the 'glass won't stick to anything.

    Then attach a wood block to the inside of the plastic, so you have something to staple the fleece to.

    Then (with wooden sticks) brace the edges of the plastic (so it doesn't buckle, you will be putting a hell of a lot of force on model plastic.

    Then stretch the fleese over the ship, stapling it to the wooden block. Make sure you get it as taught as you can without breaking the plastic. I mean "tight like a drum".

    Then take a good hard look at what you have, try to find things that might need to be redone or restretched. Because what you see in front of you is what you will have as a hull.

    Then resin the CRAP out of it. Don't go easy on it. More resin the better, it has to soak through the fleece to the PAM. BTW, only resin the part that will become the hull + a small amount so you can shape the edge as you want it. Small hull, no need for real fiberglass; probably be better without it actually...


    THEN let it dry.


    Then undo the staples & pop the plastic out, shape / sand.... put it in front of the NJ & let it sink.
     
  13. Craig

    Craig Active Member

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    Before you put the resin in try cookie dough. Just to make sure the Pam is everywhere... :)