Tooling gell

Discussion in 'Materials' started by Nick F, Jul 2, 2010.

  1. Nick F
    Joined: Aug 2008
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    Location: Auckland

    Nick F Junior Member

    Hay guys
    So im about to build my mold for a 18ft RIB. but im a bit concerned about the tooling gel. in the past I use a gravity feed spray gun with a 2.5mm tip and thin the gel 5-10% depending on temp. but iv never done a part so big I feel it will take me for ever to spray the hull with this system. also as spraying goes on the tip slowly gets clogged up so im concerned it will not get through the hull.
    What are people using in industrie?
    Popcorn gun?
    Gravity feed?
    Pressure pot?
    Any help much appreciated
    Nick:)
     
  2. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    Most of the builders are using a full sized airless system, but a pressure pot will work well. The smaller guns can be OK on small parts, but like you said, you just can get enough flow to do a large part.
     
  3. tinhorn
    Joined: Jan 2008
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    Location: Massachusetts South Shore.

    tinhorn Senior Member

    Pressure pot with a 3.5 primer gun. Accept no substitutes. (And make sure your compressor can keep up with the gun.) With a huge tip you may not have to thin the gelcoat.

    You'll make yourself crazy trying to use an itty-bitty gravity feed gun on a large mold.
     
  4. Nick F
    Joined: Aug 2008
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    Location: Auckland

    Nick F Junior Member

    Thanks guys
    Yeh just as i thought i would go nutz. i will get a pressure pot. how much gelcoat can you mix up and have it in the pot? surly it isnt 3.5gallons?


    Regards Nick:)
     
  5. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    Most people use a 2 quart pot, that's about the right amount so you don't have it go off in the gun. On large projects you may have a couple of pots ready to be catalyzed and just switch when the first one is empty.
     
  6. tinhorn
    Joined: Jan 2008
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    Location: Massachusetts South Shore.

    tinhorn Senior Member

    If you catalyze all 3.5 gallons, I wanna come watch.

    Two quarts at a time sounds right. Determine how much material your project will use, then line up your filled 2-qt. containers. Place your catalyst bottle IN FRONT of the next container to be used--this will help you avoid the embarrassment of getting distracted and placing an UNcatalyzed container of gelcoat in the pot which I've never done myself, of course, but have heard about.

    Using containers keeps the inside of the pot clean, and keeps new gelcoat away from previously-catalyzed gelcoat. Check to see how far your pickup tube extends into the pot. I wasted a lot of gelcoat before I anchored a block of wood in the bottom of my pot to raise the containers a bit.

    Use long hoses so you can focus on the gun, not on moving the darned pot around as you progress.

    Have a friend videotape you in case you really mess up, so we can all enjoy it. The worst that can happen is that your gelcoat will start to kick before a container is empty. Keep an airhose nearby with a high-pressure blowgun attached in case you need to blow hardening gelcoat out of the hose supplying the gun. I've never had this happen, of course, but I've heard about it.
     
  7. Herman
    Joined: Oct 2004
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    Location: The Netherlands

    Herman Senior Member

    We do maintenance on polyester machines, and let's put it this way: We use a lot of acetone and methylene chloride. The rest is up to you to imagine...

    Have the guy videotaping also move the pot for you. When spraying large objects an extra person just to shift things around always comes in handy. He could also mix resin, if you trust the guy. (or give him very, very clear instructions.

    The problem with spraying or even rolling is, that if the gun sucks a patch of less well mixed resin, it will immediately spread out on a large area. Undercatalisation is something you definately do not want, but is something that happens a lot.

    So mix, then mix again, continuously scraping the bottom and walls. Then pour in another container, and mix again. Now the resin up to the walls is properly mixed as well.
     

  8. tunnels

    tunnels Previous Member

    Most pick up pipes are off to one side on Pressure pots so i set the pot on a angle so even more of whats in the pot gets used .

    Remember the moment the catalyst if poured into the gel coat the clock starts ticking , if you know what the gel coat gel time is then you know how long you have to work with it minus a few minutes then you will not get into trouble . If a gun starts to gel I disconnect the air off the pot and take the lid off , then take the air cap off the end of the gun use a air gun to blow the semi gelled gel coat backwards out of the system then very quickly get acetone into the feed line and into the gun . when i set up a pressure pot system i use a regulator for the pot only as well as a air line tap to shut off the supply to the pot , I also use a regulator for the gun supply as well as a tap to isolate the gun as well . This way you have total control of the whole system . If you dont have product knowledge and understanding of the equipment you are using then you will have problems , it knowing how to avoid the problems thats important . :D
     
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