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    GRP end caps


    Posts : 35
    Join date : 2020-09-29
    Location : Nottingham, UK

    GRP end caps Empty GRP end caps

    Post  SimonH Sun Jul 18, 2021 3:05 pm

    Anybody tried using GRP sheet to laminate WTC end caps?

    Whilst building a prototype layout for WTC I used perspex but both glues (superglue & gorilla glue) I tried failed to bond, so I'm thinking of using GRP sheet to build the inner frames and the end caps using an epoxy glue.
    2 x 5mm disks could form the inner part of the end caps with room for 2 O-rings and a 3rd oversize as the outer. I can turn the disks on a lath to get the close fit.
    I am intending to use 75mm polycrbonate tube for the outer tube, as polycarbonate seem to be prefered over acrylic.

    The only down side I can think of is that I have heard GRP can absorb water and because of the fibres the surface mght not be as smooth as resin, perspex or similar materials.
    david f
    david f
    AMS Treasurer

    Posts : 2186
    Join date : 2010-11-10
    Age : 71
    Location : Cumbria

    GRP end caps Empty Re: GRP end caps

    Post  david f Tue Jul 20, 2021 9:31 am

    Again just my personal views.
    I wouldn't give up on polycarbonate, just yet. It is wonderfully tough but machinable. You can glue it with the usual solvent adhesives e.g Plastic Weld or two part adhesives like Devcon plastic welder (This is also very good for PVC)
    I have never liked Perspex - brittle and badly affected by things like superglue and even Loctite. (I would keep these things away from polycarbonate too.)
    I have never used anything other than polycarbonate for end-caps but I think that GRP sheet could give leakage problems through the laminate? (3D printed end caps have a similar problem - a lathe still has it's uses!)


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    Posts : 1
    Join date : 2017-07-23

    GRP end caps Empty Re: GRP end caps

    Post  janttu Tue Sep 28, 2021 4:17 pm

    I have used FR4 sheets to make end caps. FR4 is quite similar to GRP sheets in this context.
    FR4 sheet (and I think GRP sheets too) itself is 100% waterproof. The only problem I found
    was leaking between the sheets. I used epoxy glue in bonding the sheets together, but I was not
    careful enough. You really must use a lot of glue to ensure a proper wetting of both the surfaces and
    even then you cannot be 100% sure there is no pinholes between the sheets.

    I think the proper way to glue the sheets is to prepare them so that there is actually a tiny gap
    between them and then FILL this gap with glue etc. Or you can use a smaller diameter one
    between two larger ones and then fill the gap at the edge.

    Despite this drawback I liked the idea that you can make grooves for o-rings with this method by just
    using larger and smaller diameter discs and to construct your end cap in this way.

      Current date/time is Sun Oct 17, 2021 5:09 pm