How do I make a plug symmetrical

Discussion in 'Fiberglass and Composite Boat Building' started by crossram, Jan 16, 2015.

  1. crossram
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    crossram Junior Member

    I am building a 1960's LeMans / Can Am car and I have built a nose out of foam. I plan to put a thin layer of fiberglass on the foam and then spray it with Duratec this will give me a finished plug that I can pull a mold off of.

    Now that I am close to finished on the sanding portion I want to make the left and right side symmetrical any suggestions on how to do this?
     

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  2. waikikin
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    waikikin Senior Member

    The plan of symetry should start at the beginning of the building.....
    Given the stage you're at you need to establish some consistent points/planes to left & right of centerline, template the favoured side & flip your templates to build filler or remove to match. Once it's close, fair & smooth then paint/coat.

    Many things are not entirely symetrical but they need to be close if you can see both sides at once....:D

    Jeff
     
  3. Mr Efficiency
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    Mr Efficiency Senior Member

    Excellent advice imo.
     
  4. crossram
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    crossram Junior Member

    Thank you for the advice I agree a form would have been nice, but building it may have been more difficult than the whole project as I had very few dimensions to work off of

    I made some patterns to get to this point, but because there are so many curves I couldn't account for every inch.

    Can you give me an example of what your template would look like and how would I line them up so they were consistent side to side?
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    Imagine thin slices cut perpendicular to the centreline, vertical plane. Your template is just the flip slide of the side you like best.
     
  6. crossram
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    crossram Junior Member

    What is the best way to keep them spaced the same distance yet be able to change them from side to side? Somebody should market a system that allows you to do this quickly
     
  7. Mr Efficiency
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    Mr Efficiency Senior Member

    Making a professional, quality plug from scratch, for a complex three-dimensional shape is not going to be a quick job. Pattern making is a skilled process. If you want this to look like a factory finish product, shortcuts are going to be hard to find.
     
  8. crossram
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    crossram Junior Member

    What is the best way to keep them spaced the same distance yet be able to change them from side to side?
     
  9. waikikin
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    waikikin Senior Member

    You need to reference them to a baseline/plane.... this could be as simple as a vertical peice of plywood or perspex set maybe 6-8" in front of the car with a grid reference to template from & square off... this "plane" & grid must also be indexed to known centerline & level of the original bodywork/object.... maybe wheel arch appetures/hieghts or known symetric chassis or suspension/ wishbone attachment or similar, you may well find existing anomalies of symetry, these will need mental interpolation/adjustment for to average out.

    Jeff
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    If you have done it all by "eye" so far, it might be as well to carry it through to completion that way. Next time you can apply a more organized method.
     
  11. crossram
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    crossram Junior Member

    So I wanted asked for a efficient way to do it and Mr. Efficiency said "shortcuts are going to be hard to find" sort of ironic.

    I plan to take data points on each side of the body then use a vertical laser to mark vertical lines on each side of the car, all spaced the same distance. I will then cut some forms from what I feel is the best side of the body and then use them to duplicate the other side, this should get me pretty close.

    Thanks waikikin for the suggestions
     
  12. Mr Efficiency
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    Mr Efficiency Senior Member

    Oh, sorry I wasn't able to show you the "easy" way. Don't blame me for your not thinking your methodology through before you started this, you have hit the go button then started thinking how best to go about it, which is always likely to run up a blind alley.
     
  13. waikikin
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    waikikin Senior Member

    A "LAZOR" sounds like the way to go, I hired one once building my factory for excavation levels, really terrific if eveything starts & finishes level/vert, the rest of the time I use some clear tube water level with GI lime green cordial in it & stringlines to sight through, with these you can reference things that are out of level with some simple addition/subtraction, a helper is good too especially if they don't step on the tube...

    Jeff.
     
  14. PAR
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    PAR Yacht Designer/Builder

    A set of dividers and some templates that can be flipped from side to side, is what you're up against now. It's tedious, but the only good way to whittle down the offending areas, so they match. It's an old school approach, but it does work. Is that a Cheetah?
     

  15. crossram
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    crossram Junior Member

    Thanks it's a Bizzarrini P538
     
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