Modify/extend existing mold

Discussion in 'Fiberglass and Composite Boat Building' started by mrdebian, Feb 1, 2023.

  1. mrdebian
    Joined: Apr 2021
    Posts: 98
    Likes: 11, Points: 8
    Location: Greece

    mrdebian Junior Member

    Hi all,

    I want to extend an existing small mold (it is a kayak rim) about 2cm on a specific area as outlined with the red marks in the attached image.
    I'm looking for opinions about the recommended way to achieve this.
    The mold is about 9mm thick made with gelcoat and chopped mat and polyester resin.

    Thanks
     

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  2. wet feet
    Joined: Nov 2004
    Posts: 1,597
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    Location: East Anglia,England

    wet feet Senior Member

    Do you have the plug available?It may make the job easier.
     
  3. mrdebian
    Joined: Apr 2021
    Posts: 98
    Likes: 11, Points: 8
    Location: Greece

    mrdebian Junior Member

    @wet feet I got two of those rims, in one of them I got the plug in the other one not.
     
  4. wet feet
    Joined: Nov 2004
    Posts: 1,597
    Likes: 531, Points: 113, Legacy Rep: 124
    Location: East Anglia,England

    wet feet Senior Member

    The easiest solution is to do the modification on the plug and to bevel the edges of the mould in the region so that you can securely place the mould in position and laminate the new section.There may be a small step,but it will be easier than trying to do the job any other way.For the component that doesn't have a plug,you will have a more difficult time,much more difficult.The most convenient solution would be to use self adhesive sheet wax of 3mm-5mm thickness if you can find any.It can be formed to a good approximation to the shape and then an extension to the mould can be laminated-very carefully.Again,you must bevel the existing mould and make certain that no surface that has been coated with release wax is left exposed to the area of the mould that you are bonding to.It will be best to double gel the new piece as there is likely to be an amount of finishing needed to get a perfect surface blend.
     
  5. KD8NPB
    Joined: Mar 2018
    Posts: 163
    Likes: 39, Points: 28
    Location: South Carolina

    KD8NPB Senior Member

    Add glass, grind to shape.

    sand back, spray with gelcoat with patch booster.

    sand gelcoat, buff gelcoat, wax
     

  6. mrdebian
    Joined: Apr 2021
    Posts: 98
    Likes: 11, Points: 8
    Location: Greece

    mrdebian Junior Member

    What do you mean by saying patch booster?
     
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