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    1. Kit: , by (Yearly Subscriber) jrhaddock is offline
      Builder Last Online: Jan 2020 Show Printable Version Email this Page
      Model Scale: 1/8 Rating:  Thanks: 0
      Started: 04-12-11 Build Revisions: Never  
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      I'm building a 1/8 scale model of the RR Phantom II bodied by the French coachbuilding firm of Figoni & Falaschi in 1937.
      (If you're interested there are more details on my website www.jrhscalecars.com).

      The body shell is complete and, finally, so is the exterior mold. Now the dilemma. Do I make an interior mold and resin Fiberglass vs. Resin cast the shell or simply lay up the shell in fiberglass on the exterior mold?

      One respected modeler had recommended fiberglass (a fairly straightforward but messy layup). Another preferred resin Fiberglass vs. Resin but, based on his own experience, was working on rotational molding (basically slip casting Fiberglass vs. Resin with a mechanical device to evenly rotate the mold). Both approaches have the advantage of not needing an interior mold, and wall thickness can be managed reasonably well. Fiberglass is definitely the simplest.


      My original plan was to use an interior mold. In theory the casting Fiberglass vs. Resin would be easier, but now I'm not sure how easy it will be to control the wall thickness. The shell is only 3mm thick in some places. My plan for the interior mold would be to apply brushable silicone to the interior of the shell (to about 10mm thickness) and then reinforce that with a pourable foam. The resulting interior mold ought to be rigid enough to hold its shape after it's removed from the shell. The indents on the outer mold and the related bosses on the interior mold should hold the relative position of the two molds when they are mated together, leaving the thin space between for casting Fiberglass vs. Resin . The exterior mold is flexible enough to allow straightforward extraction of the shell (once the reinforcing walls are removed).


      The interior mold option is a lot more work, and significantly more $$$, but it would let me cast several shells (but why?). On the other hand fiberglass will be faster and simpler and I can still make a full shell for the body plus an extra partial shell for the doors and trunk lid.


      As you can tell, I'm still thinking about it!!!
      I would really welcome any input and suggestions.

      Also does anyone have any suggestions as to where I can get good advice on thin section, high detail, fiberglass molding?

      John

      Build Photos

      Fiberglass vs. Resin-figoni-falaschi-profile-jpg  Fiberglass vs. Resin-shell-fenders-jpg  Fiberglass vs. Resin-exterior-mold1-jpg 


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  1. Don Garrett's Avatar Asst. Administrator
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    Don
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    John, I've made the Madd Fabricator aware of your questions....he (if anyone) should be able to help you decide which method would work best for your project.
    Looks great by the way.
    Grandpa McGurk.....Steppin' Large and Livin' easy.
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    QUOTE QUOTE #2

  2. MADD FABRICATOR's Avatar Established Member
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    Richard D. Zimmerman
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    John, first of all let me say that's a great looking body you've created. In order to answer your question most logically I need to know , what material did you use to create the exterior mold ? once I know that I can maybe help you decide which products you are going to use to mold a body.
    Awaiting your reply,
    CHEERZZZ!!!!!!!! MADD FABRICATOR
    NEVER argue with an IDIOT, for he'll only drag you down to his level and beat you with experience !!!!
    QUOTE QUOTE #3

  3. Egon's Avatar Moderator
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    egon
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    silicone
    QUOTE QUOTE #4

  4. RonOC's Avatar VIP/Sponsor
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    Ron
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    Hi John,

    IF you were to cast a few bodies, you might be able to sell some.

    Or IF the first body was not up to your high standards, a second would not be that major an undertaking.

    The body is looking good!

    RonO
    QUOTE QUOTE #5

  5. MADD FABRICATOR's Avatar Established Member
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    Richard D. Zimmerman
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    If your body mold is made out of silicone, make sure that the " Brand" is compatable with polyester resin Fiberglass vs. Resin , before you decide to go the fiberglass cloth and polyester resin Fiberglass vs. Resin route. This also holds true if you want to use epoxy Fiberglass vs. Resin resin Fiberglass vs. Resin , instead of polyester resin Fiberglass vs. Resin .
    If you decide that you want to do a pour cast resin Fiberglass vs. Resin body you'll probably fine that urethane Fiberglass vs. Resin resin Fiberglass vs. Resin such as Smooth-On or Alumilite will work OK, but you'll have to create an inner mold piece so you can get some consistancy in your thikness. I don't think trying to roto-cast this body will give you the results you are trying to achive.
    You didn't say how thick of a body you were trying to achive, but keep in mind that any body of this size will need to have fairly thick panels to keep from warping over time, if you are using the urethane Fiberglass vs. Resin resin Fiberglass vs. Resin casting Fiberglass vs. Resin method.
    Good luck with the project.
    CHEERZZZZZZ!!!!!!!!!!!!!! MADD FABRICATOR
    NEVER argue with an IDIOT, for he'll only drag you down to his level and beat you with experience !!!!
    QUOTE QUOTE #6

  6. Herman's Avatar VIP/Sponsor
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    Herman
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    By far most silicones will hold up a few moldings in polyester resin Fiberglass vs. Resin , epoxy Fiberglass vs. Resin resin Fiberglass vs. Resin or anything else. So lets break down the options:

    - epoxy Fiberglass vs. Resin / glass fabric. Disadvantage is cost and availability. You will need a laminating resin Fiberglass vs. Resin , which in small quantities can be bought in remote control modelling stores, or online. Some brands in the USA are West System, System 3 or MAS Epoxy Fiberglass vs. Resin . Epoxy Fiberglass vs. Resin is NOT compatible with glass mat (the random oriented stuff used to fix holes in cars) so you need a woven material, which can be more of a challenge to get into all corners. One trick is to thicken the epoxy Fiberglass vs. Resin for the first later, and fill all odd crevices with that paste before working with fibers.
    Epoxy Fiberglass vs. Resin has a tendency to continue curing Fiberglass vs. Resin when heated. To compensate for that, heat up the mould and body (still in the mould) for a period of time. Easiest to do is to put it in the sun for a while, perhaps in a black plastic bag.
    Furthermore epoxy Fiberglass vs. Resin can cause allergic reactions, usually due to contact with the resin Fiberglass vs. Resin . use good gloves (nitril ones, not latex) and wash off spills with soap and water, not acetone.

    Polyester and glass mat.
    Smells like nothing else, so work outside, or your wife will kill you. Process is faster than epoxy Fiberglass vs. Resin , and thickness build-up is also faster. Can be picked up in most stores, for sometimes astronomic prices. Try and find a boatbuilder or other polyester user, and buy from him. (bring your own pots or buckets). The curing Fiberglass vs. Resin agent (in USA falsely called "catalyst") is dangerous. Do not spill, as it may cause fire. Any rag that is used to clean a spill, should be soaked in water, then disposed off. Do not get the catalyst in contact with materials that can burn (wood, paper, etc) or metal (except stainless steel). If you ever get this stuff in your eye, rinse IMMEDIATELY with loads of water (get someone to help) and call a docter. He might save your eye. Safety goggles are perhaps a good idea.
    The trick with thickening the resin Fiberglass vs. Resin for the difficult spots also applies here.
    Glassmat can be used, which is a help, as you can apply it patch by patch. Make sure you get rid of the bubbles, especially in the first layer. One layer builds up about 1mm, normally. 2-3mm is the minimum for a sturdy body, although the hood (bonnet) could do with less.
    No need to postcure, although it helps to get rid of the styrene Fiberglass vs. Resin smell.

    Casting Fiberglass vs. Resin . Your challenge is to make an inner mould. You could source sheetwax in the desired thickness. This is self adhesive wax, in calibrated thickness. It can easily be cut, and with a hairdryer can be shaped. Test the adhesion first on silicone. If it is difficult to remove, then apply a layer of PVA (poly vinyl alcohol Fiberglass vs. Resin ) in your mould first. This liquid dries into a film, which can be dissolved in water. So when the sheetwax needs to go, soak the thing in water for a while, after which you can remove the stuff easier.
    After applying sheetwax, you can cast your inner mould. Think of something to keep the inner mould in position during casting Fiberglass vs. Resin . The window areas are great for that (do not apply sheetwax over the windows). Make sure you apply a release agent (release-ease 200 or similar) to prevent adhesion between the 2 silicone moulds.
    Pouring can be done using a hole in a deep point (roof section). When the wax is finished, place a stick some 1/2"in dia in the desired location, then pour the inner mould. After removing the stick, you have a casting Fiberglass vs. Resin spout. Insert a funnel, and cast your part. Afterwards you can remove the excess resin Fiberglass vs. Resin . You can make part of the spout thinner Fiberglass vs. Resin , close to the roof, so you can break it off before removing the inner mould.

    Smooth-On has some nice materials, and a nice booklet about casting Fiberglass vs. Resin . Good luck!
    QUOTE QUOTE #7

  7. jrhaddock's Avatar Yearly Subscriber
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    Wow, thanks for all your inputs ... they're really helpful.

    The outer mold is Smooth-On's Mold Max XLS-II, a tin- cure Fiberglass vs. Resin silicone rubber. I chose XLS-II because of its very low shrinkage ... pretty important given the size of the body shell.
    Previously I had resin Fiberglass vs. Resin cast the Art deco-like seats using Smooth-On's OOMOO silicone for the mold and their SmoothCast urethane Fiberglass vs. Resin resin Fiberglass vs. Resin . That worked great but, obviously, the shell has bigger challenges.

    John


    Fiberglass vs. Resin
    QUOTE QUOTE #8

  8. jrhaddock's Avatar Yearly Subscriber
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    A couple more things:

    My goal was to keep the wall thickness of the doors to 3mm. However, the doors will be reinforced with an inner panel, and the space between used for the wind up/down windows. Elsewhere I can afford to go thicker ... significantly so, if necessary. One advantage of a single piece shell is that, to some extent, it is self reinforcing which, hopefully, will reduce warpage.

    If I went with an inner mold, I was thinking of using Smooth-On's Rebound 25, a self-thickening brush-on silicone that will work on vertical surfaces. It's laid down in layers to get a 3/8 (10mm) thickness. Then it needs to be reinforced on the inside. For that I was thinking of using US Composites' Pourable Expanding Urethane Fiberglass vs. Resin Foam. It too can be laid down in layers and, since the inner mold will be open at the top, managing expansion should be straightforward!! The inner mold will then be very rigid.


    Fiberglass vs. Resin
    QUOTE QUOTE #9

  9. MADD FABRICATOR's Avatar Established Member
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    Richard D. Zimmerman
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    John, Smooth-On makes some very good two part foam kits, which are available in different densities. I've used it in the past to do exactly as you're talking about. Where-as you seem to be quite famialiar with Smooth-On products stick with a brand you've had experience with, and trust.
    Also, Herman gave some very good advice about working with the epoxy Fiberglass vs. Resin and polyester resins.
    Keep us posted as to the progress with your project.
    CHEERZZZZZZZZZ!!!!!!!!!!!!!!!!!!! MADD FABRICATOR
    NEVER argue with an IDIOT, for he'll only drag you down to his level and beat you with experience !!!!
    QUOTE QUOTE #10

  10. Rick's Avatar Member
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    Gentelmen, this is an interesting topic. Thanks to each of you for your input. One of the great things about this site is not only the wide range of talent here but more importantly, that everyone is willing to share it.

    Next time any of you is laying up or casting Fiberglass vs. Resin a body or a part, it would be great if you could post some photos and a description of how its done.

    Thanks!
    QUOTE QUOTE #11

  11. jrhaddock's Avatar Yearly Subscriber
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    John
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    Finally!! The front fender is cast.
    And, much to my delight, it came out better than I expected.
    Even the very thin (1 mm) wall along the running board came out well and is quite strong.

    For those that are interested, I used Smooth-On's TASK-4 resin Fiberglass vs. Resin ... a very strong, low shrinkage polyurethane material which is especially designed for thin sections (down to 0.75 mm).

    Attached are two photos. One shows the cast fender next to the master and the other shows the mold before the two halves were separated. The two square rods on the left and the two tubes on the bottom right hand side act as mold pins to keep the two molds in alignment. The styrene Fiberglass vs. Resin tubes don稚 bond to the silicone so they are relatively easy to pull out.

    The two mold halves used about 10 lb of silicone (roughly $100) but the fender itself only used about ス lb of TASK-4 (less than $10). Obviously, the cost is in the molds.

    Now I have to do the other fender, but that should be straightforward.

    In the meantime I've decided to make the body out of fiberglass. The relatively simple, tub like shape, is ideal for fiberglass and it will be a lot cheaper than making an interior mold. Plus I was (am) concerned that even a slight misplacement of the exterior and interior molds could seriously affect the wall thickness. (Or maybe I'm just chicken!!).



    Fiberglass vs. Resin
    Attached Images Attached Images Fiberglass vs. Resin-img_7411a-cmp-jpg  Fiberglass vs. Resin-img_7417-cmp-jpg 
    QUOTE QUOTE #12

  12. MADD FABRICATOR's Avatar Established Member
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    Richard D. Zimmerman
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    Looking Great !!!!!!!
    CHEERZZZ!!!!!!!!!! MADD FABRICATOR
    NEVER argue with an IDIOT, for he'll only drag you down to his level and beat you with experience !!!!
    QUOTE QUOTE #13

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