cloth width in large panels

Discussion in 'Fiberglass and Composite Boat Building' started by Semloh, Dec 17, 2005.

  1. Semloh
    Joined: Jan 2005
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    Semloh Junior Member

    When making a large panel can you use two rolls side by side or do you have to find one wide enough to cover the whole panel?

    If you can use two side by side how do you set them? One over lapping the other a certain amount or just butted up next the other?

    Do you lose some strength this way?
     
  2. Karsten
    Joined: Jun 2004
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    Karsten Senior Member

    You have to overlap the cloth. Otherwise how are the forces going to get acress the gap? The amount of overlap depends on the cloth and the shear strength of the resin. You have to work out the maximum force your cloth can transfer and then work out how much overlapping area you need so the resin can transfer this force in shear. There will also be some stress concentrations at the beginning and end of the bond. So you could carry out some extremely tricky calculations or just overlap 50mm (2 in). That's sort of the safe standard.
     
  3. Semloh
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    Semloh Junior Member

    Thank You
     
  4. Ssor
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    Ssor Senior Member

    Assuming that you are not building a single ply panel you can but the cloth in each ply and stagger your joints so that you over lap each joint with whole cloth. If you build with overlapped joints and fail to distribute them across the entire panel you will have a ridge down the middle that is twice as thick as the rest. You could easily alternate your layup so that the first layer was laid from left to right and the second layer was laid from top to bottom. You should always plan a layer of chopped strand mat between layers of woven cloth.
     
  5. John ilett
    Joined: Nov 2003
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    John ilett Senior Member

    There also many glass fabrics which have a tapered edge specifically for overlaps so there is no excess thickness. Wide rolls are often 4ft/1.27m wide.
     

  6. makeitfly
    Joined: Dec 2005
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    Location: new zealand

    makeitfly Junior Member

    As mentioned 50mm is the minimum amount to do any overlap anywhere in hi stress situations it is 80mm to 100mm when using cloths and unidirectionals regurdless of what sort of resin you are using .
     
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