Ideal radius on corners for Biaxial

Discussion in 'Fiberglass and Composite Boat Building' started by gary1, Jun 2, 2007.

  1. gary1
    Joined: May 2006
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    gary1 Senior Member

    Morning,
    When laminating over ply what is the ideal size radius to have on corners when laying fabric, this mainly concerns the chine area where the chines meet the side of the hull. I will be using 450 gm 0/90 (15oz) Biaxial Tape on the seams to strap the hull together prior to laminating it.
    Thanks
    Gary
     
  2. nero
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    nero Senior Member

    I am using 10 qz biaxel glass. It lays and bonds well over a 14 mm radius. The bigger the radius the less stress on the glass.
     
  3. marshmat
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    marshmat Senior Member

    Basically, the bigger the better, Gary.
    For wet-layup in ambient conditions with your 450 gsm tape, I'd say 20 mm is great and 15 mm is probably doable. Below 10 mm and you'll get air bubbles trapped underneath unless you vac-bag, the fibre will be too stiff to hold such a tight corner without help.
     
  4. gary1
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    gary1 Senior Member

    G/Day Nero, Mat
    Thanks for the advice the chine panels and sides are made off 6mm ply, so I'm not exactly sure what size radius I will be able to shape that to. But I will try to get it as large as practicable so the fabric can take the bend as easily as possible and lay down on the ply hopefully without any air bubbles. Thanks Again
    Stay Safe
    Gary
     
  5. nero
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    nero Senior Member

    You can glue a triangle profiled strip of wood to the inside of the joint between the ply pannels. Then you can radius to your hearts content. Will need to glass both inside and outside of the joint.
     
  6. gary1
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    gary1 Senior Member

    G/Day Nero,
    Mate to late, I've already taken to one side with the electric sander and sanding block looks like it might turn out ok. I'll keep it it mind for next time, although I can pretty much guarantee I will build out of Alloy next time. There's way to much sanding in these composite boats for me.
    Thank's again for your'e advice
    Gary
     
  7. mike steiger
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    mike steiger Junior Member

    I find that a 3/4 inch radius works well when using the biaxle material and put no stress on the fibers and no voids in the lay up. Hope this helps.
     
  8. JR-Shine
    Joined: May 2004
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    JR-Shine SHINE

    15mm is fine for most spots. We specify 12mm for most of our fillets. Around stringers and transoms, I go a little larger, maybe 18mm. -- thia woudl be for plywood/epoxy/fiberglass composite.

    For foam core, we use trapezoid "hats" of foam which really helps cut down on epoxy use

    sometimes the designer will specify, in which case go by that
     
  9. frosh
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    frosh Senior Member

    There are two other options that havn't been mentioned yet. Firstly if the radius is going to less than 15mm which it will very likely be, what about using regular woven 6oz. tape? Biax is quite stiff and heavy and wont work in small radius curves unless you do the following and maybe get the odd air bubble. I have done this myself and it was fairly successful. I used fairly long pieces of duct tape at 90 degrees to the line of the chine and overlapped the strips a fair bit. It uses a lot of tape and is time consuming but it is almost as effective as vacuum bagging the chine area only. After peeling off the tape once the resin has set, there is still some sanding to do. Regular woven tape of lighter weight is far easier. You need to ask yourself if the biax is really needed for your application?
     
  10. gary1
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    gary1 Senior Member

    Afternoon Mike,Shine,Frosh
    Sorry I haven't replied sooner, I had to go fishing for a couple of day's. I ended up putting a radius of approximately 18mm(3/4inch) along the chines and around the transom,after laminating I will fair all these edges back out to a nice clean sharp edge. There are a couple of pictures in my gallery to show the actual radius I ended up with and how far I'am along with my build so far. Frosh your'e right I could most likely get away with a lighter fabric tape but I've got a fair bit of it and just want to use it up. The only real reason I'm even taping it up is to hold the the whole structure together while I'm laminating the hull, at the moment everything is being held together with Epoxy glue /putty and in places I will have to climb on top of the thing whilst laminating it. Thank's everyone for taking the time to help out I appreciate it.
    Stay safe
    Gary
     
  11. waikikin
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    waikikin Senior Member

    Just adding my 20c worth "cos I use the 20c peice for radius every other day. All the best from Jeff:)
     
  12. gary1
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    gary1 Senior Member

    G/Day Waikikin,
    Mate thought about the 20 cent piece idea but was a bit concerned about the inflation aspect of the whole thing so I went with the $1.00 coin just to try and keep ahead of it. Yeah yeah I know but I couldn't resist it.
    Stay safe
    Gary
     

  13. waikikin
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    waikikin Senior Member

    rampant inflation

    Crikey, you get less radius for your dollar every day and even less radius for 2 bucks.Jeff:)
     
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