please advise on making a male mold?

Discussion in 'Fiberglass and Composite Boat Building' started by tugboat, Aug 10, 2013.

  1. michael pierzga
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    michael pierzga Senior Member

    If you go wet layup hire a few helpers. You will need them.
     
  2. BernardG
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    BernardG Junior Member

  3. rwatson
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    rwatson Senior Member

  4. groper
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    groper Senior Member

    I know the guy who did that... his first boat built via infusion aswell... it had a few problems but not a throw away by any means... it was done over a surfaced male mold too but he used tye wrong core material for the job. I advised him against it and predicted the problems with using the scrim backed contour foam blocks. He should have used a double cut type of foam core.

    The job looks like it goes ok, but he ended up with dry spots ij the laminate and a very large dry patch on fhe tool side at the top where he had his vacuum lines - you cant see the tool side of the core. Its caused by the large gaps in the foam blocks race tracking the resin to the vacline and isolating the vacuum before the tool side had a chance to fully wetout. To fix it, he needed to grind out the effected area after demolding it, and go over it again on the inside of the hull in the bilge area...
     
  5. rwatson
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    rwatson Senior Member

    It was probably still quicker than hand layup, even with that hiccup.

    I have nothing against the technique, but its like all building skills. You need to work your way up the learning ladder.
     
  6. tugboat

    tugboat Previous Member

    Watson for once we agree...I very much wish I could just throw on a vacuum, plain wrap and tubing on my male mold and go but I'd end up with landfill...
     
  7. BernardG
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    BernardG Junior Member

    Sorry, sometimes my english play tricks on me! I missed the "ups" part.

    Regards,
    Bernard
     
  8. Cat Cruiser
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    Cat Cruiser Junior Member

    My preoccupation- accuracy, I think could suffer. What the plans call for and what actually gets built could definately be two different sizes
    ( speaking about - accounting for material thickness) I could see it being way to easy for a first timer building the male forms, or what ends up being the finished model to net-not thinking ahead. Then his hull that he "contrives" out of foam strips and his skin coating ends up being 5/8's over the actual design size. (but there are not aerospace QC agents coming in to sign off on it either in the marine field)
     
  9. tugboat

    tugboat Previous Member

    if that were the case would it make much difference with 5/8th of an inch over the actual design parameter? I could see it adding a couple hundred lbs. displacement maybe. But not anything that would affect the performance or stability.
     
  10. pdwiley
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    pdwiley Senior Member

    Nice engine. I recently gave away a Lister FR2 diesel with a 3:1 box on it because I was never going to get to using it myself and it needed a rebuild.

    However if you ever want to part with the CPP stuff - keep me in mind. I want one.

    On steam plants I just got given a pile of engineering books on them, some quite old. Haven't had time to read them yet.

    PDW
     
  11. pdwiley
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    pdwiley Senior Member

    No, I personally wouldn't give it a second thought. It'd make no practical difference.

    PDW
     
  12. tugboat

    tugboat Previous Member

    That lister would have been nice- what's the weight on that lister? this petter is about 1300 lbs. with gear...that's around 590 kg's metric.

    sift through your books and of you find one called "steamboats and modern steam launches" circa 1961-1963, its considered the bible of steam enthusiasts..i think you would enjoy it...
     
  13. tugboat

    tugboat Previous Member

    SamSam and Groper- if your still around- would costs balance out if using epoxy?

    let me explain;
    I want to use use triax 22 oz. 6 layers. three layers on each side of the c-flex.

    it has strength in three directions. and its cheap 462.00 per roll. believe it or not but WR and CSM is about 9.80 per yard! its more expensive than the knitted.



    my thinking on this is that epoxy has a higher cps than iso (500 cps) and v-ester (600),
    but epoxy meets the perfect requirements 800-1000 cps, low shrink(2%).

    so if I used an all epoxy laminate I estimated my costs by doing this for the amount of epoxy would balance out by using less of it than polyester which would produce more waste(?) than poly- I am told that you use less epoxy than poly in a laminate in either a hand layup or resin infusion. is this true? and by how much??


    using the formula for approximating resin required:


    415 sq ft hull / 12.5 sq ft (a running yard) = 33.2 yards x 22 oz. = 730 oz. total for 1 laminate.


    so I need 6 layers x 730 oz. = 4380 oz's total x factor of 1.4 to 1.5 approx. (resin to glass) = sub total of 174 kg's- but add 5 kg's as extra.

    so I should theoretically need 180 kg's of resin for my bare hull laminate.

    Ive added 6 kg's as a buffer for waste etc.

    Right now though I would like to do a full V-ester approach.

    1. what are the benefit's of using v-ester over GP resin? is there less styrene fumes?

    2. could I save with using epoxy?- I know it will be more expensive in the grand scheme- but if I need an amount less than polyester- then it might only cost marginally more to go with a superior quality resin such as epoxy over v-ester? would the benefits be worth the extra costs?


    at the very least- I had previously overestimated my resin.

    I thought I would need at least two drums of resin but it turns out Ill only need about 40 gallons of it for my hull topsides to keel.

    I am using 6 layers of triax. however there is also the c-flex wetout which adds another 20 gallons of resin.


    summary
    epoxy- more expensive-but is the cost benefit worth it? there is also sanding between coats. or perhaps with slow cure resin could do the layup in one day with a couple helpers?

    v-ester.
    not bad in price. I thought it would be more but turns out to be 6.20 a kg. I need 180 kg's so not too bad and the best of the poly resins.

    I know epoxy is superior but its costs are superior too...

    Im thinking v-ester right now..
    does anyone have the cps and/or the shrinkage in % for v-esters?
     
  14. pdwiley
    Joined: Jun 2008
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    pdwiley Senior Member

    Pretty much the same weight - a touch over 600 kg IIRC. I bought it off a scrap dealer for $100 because I couldn't bear to see it scrapped. Gave it to a local collector who restores antique marine diesels when I decided I'd never get to it. I have 2 other Lister marine diesels (air cooled) anyway and they both run.

    What I need to do is get my boat *finished* and out of the shed. Then I can think about the next project. I can build anything up to 12m LOA and 3.9m beam without dramas, up to 15m LOA if I really had to.

    However I think the next project will be a nesting dinghy.

    PDW
     

  15. tugboat

    tugboat Previous Member

    I came across a lister HA3 two years ago-- they wanted a couple hundred for it. I really wanted it since they are air cooled and a really good engine when running- but the engine was seized solid. the owners didn't know a thing about it and did not oil the cyls. it was left out in a field -even had the Lister Blackstone transmission on it. after a lot of debate and inquires into seeing what I would be getting into to unseize the pistons I decided not to buy. Sad. it was used as a saw mill engine...the guy died and then it rotted away in a field...

    I would be interested to see the launch...do you still have bad internet service? if not - post some vids of launch?

    or at least post your pics on here...our summer is ending so I believe yours is beginning soon--how close are you to launch??
     
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