Glen-L.com

Hi all,

I've tried to exsplain this as least confusing as I can lol! so please bare with me!

If you wanted to make a mold for fiberglassing... rather than have to make a female version 1st, then apply your tooling gelcoat then fiberglass and then remove your male mold for producing your part...

Would it be possible to paint the inside of your 1st mold with 2k car paint, having spent alot of time on prep and achiving a good finish after painting... then use the female mold painted with 2k car paint, apply your release wax to the 2k surface and use as a normal mold, applying the finish outta gelcoat to the 2k waxed face

Would this work, if the durability of the mold wasnt an isue?

Doing this would save having to make two molds, to get your male mold to produce parts

I hope this makes sense! thanks for reading!

I may be confused by your post, but production glass boats are conceived and built in this order:

1.Make the hull,deck,or part,which becomes the male mold or "Plug".
2.wax& polish, then laminate up the female mold(gel coat,build-up laminates,bracing)
3.separate & pull the braced female mold off the male "Plug"
4.Repair any flaws,wax,polish female mold
5.spray in gel coat,then laminating schedules,stringers,bracing,etc
6.pull the hull,deck,part,etc from the mold

I've made one-off parts this way also

_________________
Boat building can best be defined as an endless series of
tragedies obscured by the occasional miracle, followed by a good bottle of beer.

Don't Dream Your Life, Live Your Dream

Sorry, you've put it in away thats easyer to relate to

Is it possible to scratch off step 1 and 2. Make a female mold from MDF and paint the inside with 2k car paint. then use this as your mold for your part. Thus knocking out the need to make a male "Plug" to start with

Ied say just paint the inside of the female mold with gelcoat, but then you would be sanding and polishing for years to get a good finish to mold from.

Hi GTM and welcome, Why not just build the boat and fiberglass it like the rest of us There will be a lot of work and money in building two hulls. Did you have a look at the plans of some of the bigger boats http://www.glen-l.com/boat-plans-catalo ... can-build/ I'm sure there is something that will meet your needs.

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Doing it this way would mean you wouldnt have to make two hulls though? Sorry my first post was the wrong way around and confusing.

Rather than make a male plug, to get your female mold. Make a female mold spray the inside in 2k, then wax it... theres your mold, so you dont have to make the plug to start with.

obviously doing this would be very hard with a v shaped hull, far easyer to make a plug and produce a mold from that yeh. I'm after making a very simple flat bottom boat, so it would be easyer to make a female mold first?

it would be easiest to just build it out of wood and fiberlass the outside of the boat sand smooth and paint it and you are done

I believe you COULD,but something as a hulls complex curves etc,to get faired properly, would be difficult I believe, to do in the method you described.

In other words in my opinion, it would be hard to get things right shape working inside of the mold....it's tough enough to get things right working the on the outside

I have an old How to Build 20 boats magazine from the early 60's that shows how to make a male mold from a form and lath strips, cover with plaster, then laminate in fiberglass.

Then they grind smooth,pull the fiberglass skin off,setup level and add all the interior bracing

Seems like a lot of work for a one-off boat.

I'd just build a wood boat and glass it like Fergal and Red said.....much easier,cheaper,lighter for a one-off home builder

_________________
Boat building can best be defined as an endless series of
tragedies obscured by the occasional miracle, followed by a good bottle of beer.

Don't Dream Your Life, Live Your Dream

The "Plug" is a model of what you are trying to make. It is not used in making the actual part in any way.

Need a model of some form. I have used everything from the original part, to XPS foam and modeling clay to make a plug. The plug is then covered with something not affected by polyester resin, and capable of taking a good smooth surface. Plaster works, setting drywall compound is better, but sanding it smooth is miserable, Wax the plug with some mold wax.

The now prepped plug is covered with release agent, and a layer of TOOLING gel coat (not production gel coat, they are different creatures). Apply the backup cloth-any high drape cloth is good, Then it is covered with chopped strand. (hand layup works, but good grief, that is a load of work.) the supporting structure is added to prevent warping, and generally create a stiff mold once the plug is pulled. More chopper gun work to bond in the supports. Make a decent flange.

let resin cure.

pull plug (hoping you got enough release on everything, and filled any negative recesses with clay.) sand it out to 800, fill voids, be sure PVA is all rinsed out.

There is your mold... hopefully

Splash the mold with a cheapo material (make a few castings to discard, just a sort of break-in to be sure you are going to get a good casting later.)

To make part, wax mold!!! spray release agent into mold. let dry, repeat. pray you got enough on. dye, then catalyze your gel coat, spray the mold. Looking for a decent build up here, but not a saggy mess. Start laying the cloth, if that is what you are using, or just stand back and start the chopper gun. Build up your overall thickness, then insert any cast-in bracing. Cover your structure with chopper strand, cloth, whatever you are using, insert any final reinforcement cloth, ant discarding braces needed. Now spray with a wax-bearing coat of catalyzed resin. Cure the part, and again pray you got the release/wax coverage good. Pull the part, and there it is... you first part from the mold. dance around the shop, get an IPA, and admire it. Wonder why you used that funky colour gel coat. Get another IPA, and repeat the process as needed.

This is really a "reader's digest" condensed version, but you get the idea. I have used this method to make everything from car parts to aircraft components. It's really easier than it sounds.

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