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  1. #1
    Corsair2013's Avatar
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    Question Help Making a Hatch in Fiberglass Fuselage

    I am new to Fiberglass planes - normally I work on wood so this is outside my norm.

    I have a Skyshark 82" P-40 and want to make a Hatch in the plane to mount the power switches, fuel Dot, etc. I have seen builds where you make a copy of a section of the fuselage then use that to make a hatch that will fit into the hole you cut out.

    If someone knows how to do this and would be willing to walk me through all the steps I would appreciate it very much.

    PM me and I will get in contact.

    Thanks

    Keith
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  2. #2
    foodstick's Avatar
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    I am by no means the expert on this, but when I have done it I carefully cut the hatch out with exacto knives or a thin cutting wheel on my dremel. I then build a wooden box that sits back inside the plane to hold your switchs. I glue and or glass the box in...

    Then since I can't make a hinge work dead on to save my life ! hahahahah .... I usually build some back structure into the hatch, I mount a pin that goes forward into the new box.. and I put magnets on the back edge so it clicks closed. I usually attach it also with a small fishing leader so I can open up the hatch and the piece will be right there..and not on the ground lost or getting stepped on.

    Thats my low tech way of doing it.

  3. #3
    SCALECRAFT's Avatar
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    This is how I have seen vinyl floors repaired.

    They take a piece of vinyl, cut a size as needed to cover the damaged area then place the repair piece on top of the damaged section and use the repair section as the cut guide. The repair section is the exact size and shape since it was also the cut guide.

    So, in your case, if you WAX 3 times and PVA the section of the fuse you want to duplicate,( I) put bondo on the section to create a throw away mold to layup a section of the fuse to cut a "hatch" out of. Then take your new molded and trimmed "hatch" and use it as your cut guide. Then you have a clean fit and cut line. Make Note to adjust for glass thickness when on final install of internal support for "hatch'

    Hope that helps

    steve

  4. #4
    Corsair2013's Avatar
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    Wow, I don't think I understand much of what you just said. I get the idea but remember _ I know very little of fiber glass and molds.

    I "assume" the wax is to keep it from sticking when I cover the outside of the fuselage? What is PVA?

    I don't want to waste your time as I think I need step by step instructions and I don't even know what products - wax, PVA, glass, etc to use.

    I get the idea I want to make a replacement section of the fuselage then when I cut out the hole my replacement piece will be bigger than the hole then I cut it down to fit the hole exactly so there is no seam.

    If you have time I can call you or we can email back in forth but again I will need step by step guidance on this.

    Thanks

    Keith

    Quote Originally Posted by SCALECRAFT View Post
    This is how I have seen vinyl floors repaired.

    They take a piece of vinyl, cut a size as needed to cover the damaged area then place the repair piece on top of the damaged section and use the repair section as the cut guide. The repair section is the exact size and shape since it was also the cut guide.

    So, in your case, if you WAX 3 times and PVA the section of the fuse you want to duplicate,( I) put bondo on the section to create a throw away mold to layup a section of the fuse to cut a "hatch" out of. Then take your new molded and trimmed "hatch" and use it as your cut guide. Then you have a clean fit and cut line. Make Note to adjust for glass thickness when on final install of internal support for "hatch'

    Hope that helps

    steve
    P-40 Brotherhood # 82
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  5. #5
    saramos's Avatar
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    PVA is polyvinyl alcohol is a water based liquid plastic. It is used as a mold release and can be brushed or sprayed. It adds another layer of protection against parts sticking to a mold.

    The technique Scalecraft is describing is to use the section of your fiberglass fuselage as a pattern for making a mold. You wax the section of the fuselage you want tduplicatete and coat it with PVA. Once it's dry, you can coat the area with a thick layer of Bondo. Once the Bondo cures, you can pop it off your fuselage and use it to make duplicate fiberglass parts. You wax and PVA the Bondo mold, lay down a couple of layers of fiberglass, and you now have a duplicate of the fuselage section, which you can use to make your hatch covers.


    I usually get my supplies from ACP Composites, CST Composites Store or my local hobby shop. I like West Systems epoxies, but for just a one off part, you could even use hobby shop 30 minute epoxy. For fiberglass, two layers of 5 oz glass should work out fine.

    Cut your fiberglass and lay it down on some wax paper. Then brush on the epoxy until it is soaked through. Lay it in your mold. Repeat with a second layer of fiberglass. Once done, squeegie off the excess epoxy and let it cure. Once it's fully cured, pop it off the mold and proceed to cutting out the hatch.

    Scott
    Last edited by saramos; 11-24-2013 at 03:04 AM.

  6. #6
    Corsair2013's Avatar
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    Scott,

    Thanks! I really appreciate you explaining the process. I have looked at a couple of threads and builds and video on YouTube but wasn't for sure on how to do what I needed.

    A couple of questions.

    1. What type of WAX do I use? - Do I apply and buff then apply buff - 3 times?
    2. Do I apply just 1 coat of PVA?
    3. How much Bondo do I need - Thickness? Do I need to put sides around the area I want to duplicate so it will hold the Bondo and make it thick?


    thanks again

    Keith

  7. #7
    saramos's Avatar
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    You want to use a wax with a good carnauba content. You can get waxes from a composite supplier, or even use an automotive wax like Turtle Wax. Yes, you apply, buff and repeat. To ensure you have no problems with your fuselage, I would go with a couple of coats of PVA. Spraying is the best method to apply to avoid the possibility of brush strokes. I have not used the Bondo method myself, so perhaps Steve can give you and answer on that. It will have to be thick enough to stay self supporting and stable on it's own. If I were to hazard a guess, I would build up at least a 1/4" thickness in a couple of coats.
    Don't forget to de-wax your fuselage before applying primer/paint.


    Scott

  8. #8

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    I think I read somewhere to avoid waxes containing silicone due to potential finish problems.

    ghost

  9. #9

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    Here we go! Get 'mold release wax' and wax your part 3-4 times with a good buffing between wax applications. The wax fills and smooths tiny imperfections on the surface of the part. Lay down some masking tape a good two or three inches around where you want your hatch. Make a paper pattern of hatch and the cut and trace pattern onto the fuse using a Sharpie pen. Somewhere outside of hatch dimensions put three tiny glue blobs in an asymmetrical pattern to act as 'keys'. Spray PVA (preferable to wipe-on kind). Spray 3-4 light coats (wipe-on kind is usually one application). Cut some 4oz glass cloth to fit the masked area. 4 layers should be plenty. You want it to be pretty stiff so the size of the hatch will dictate the layers you apply. Lay cloth on hatch area and stiple the resin thru the cloth onto your fuse. Repeat for each layer of cloth applied. Once this cures trace the outline of hatch onto the outer surface. Your can re-use your paper pattern for this. Now pop the 'mold' off the fuse. Wash with soapy water. Dry. Now you will do the same thing to the mold as you did with the fuse. Wax the inside a few times, spray PVA etc., etc. When cure trace the hatch using the Sharpie pen (be sure to mark orientation like 'fwd' or 'top' or something), pop the hatch out then cut to shape. Now all you gotta do is fix it to your fuse after washing with soapy water. I use Fibre Glast products and mostly use polyester resins. Good luck and have fun!

    P.S. the glue blobs keys the mold to the fuse in case you want to check alignment or re-position whre you want to cut the hatch.

  10. #10
    Corsair2013's Avatar
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    thanks
    P-40 Brotherhood # 82
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    Keith

  11. #11
    stevegauth30's Avatar
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    Hey corsair, I'm still learning this stuff right along with you, just a few steps ahead. These guys know what there talking about. I was like you, pretty much needed step by step. I'm now almost done glassing my first warbird, and I have to say, it's really not as difficult as I thought it would be. I'm really enjoying the process and plan to glass a lot more. Ask a lot of questions if your not sure because these guys like to help newbies like us. My only advise, ( from the tiny bit of experience I have) is the more time you spend squeeging off the excess, the less time you have to spend sanding and filling. Have fun.
    CUB BROTHERHOOD # 151, CORSAIR BROTHERHOOD # 80, CLUB SAITO # 804, WACO BROTHER #242, P-47 BROTHER #98, GLOW HEAD #1

  12. #12
    Corsair2013's Avatar
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    I just completed making my mold for my hatch Sunday night. I came out really good. I waxed the fuselage then put down West Epoxy then built up 6 layers of 6 oz and 1 layer of 3/4 oz. It came right off the fuselage and smooth as a baby behind.

    Even all the markings come out in the mold raised up just right.

    I will make my first part out of the mold this weekend and should have all the parts to install the hatch before xmas.

    You are correct - with the help of everyone out there and watching YouTube I figured out how to do the simple stuff. The next step is to make a Big mold for the Canopy and Cowling. I want to put a sliding Canopy on my plane and the canopy that came with it is just way too thin so I will need to make a plug then glass it then make me a home made Ther****rmer.

    That will be a challenge but I found a local guy who might help me.

    Good luck with your stuff!

    Keith
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  13. #13

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    Yayyyyyyyy!


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