[PSUBS-MAILIST] Fiberglass

Fri May 8 16:39:06 EDT 2015

Hi Scott, I used Loctite spray, product number LOC1713065. Lots and lots of
it. Case-loads.

Best,

Alec

On Fri, May 8, 2015 at 4:18 PM, via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Alec,
>
> Maybe a dumb question, but what kind of glue did you glue the foam with?
>
> Thanks,
> Scott Waters
>
>
> -------- Original Message --------
> Subject: Re: [PSUBS-MAILIST] Fiberglass
> From: Alec Smyth via Personal_Submersibles
> <personal_submersibles at psubs.org>
> Date: Mon, May 04, 2015 8:33 am
> To: Personal Submersibles General Discussion
> <personal_submersibles at psubs.org>
>
> Hi Scott,
>
> Coincidentally your timing is really good, because I just finished four
> rather complex-shaped MBTs for the new sub. Since my sub is a one-off
> rather than a series production item, I used the method of glassing foam
> plugs that are then dissolved, rather than making molds. To summarize:
>
> - The plugs are a sandwich of many layers of pink home insulation foam
> from HomeDepot. When I did Snoopy's saddle tanks I cut out the sections
> with a hot wire, but this time I realized my jig saw does the job in about
> a tenth the time. Step one is to cut a whole bunch of sections and glue
> them together. If I weren't so tight-fisted, the ideal solution here would
> be to mill a single block of foam using CNC equipment, but I get by with
> what I have on hand if it'll save money - and a milling job would probably
> take quite a lot of it.
>
> - The glued sections are only a rough draft of the final form. Next you
> have to shape them until the steps between sections are gone and everything
> is nice and smooth. I use three tools to go from the draft to the final
> product, in this order:
> 1) A plain old wood saw
> 2) A Stanley Surform shaver, with flat and or rounded blade fitted
> depending on the surface. This thing is absolutely essential and I use it
> for 99% of the job. See
> http://www.stanleytools.com/default.asp?CATEGORY=SURFORM+TOOLS+AND+BLADES&TYPE=PRODUCT&PARTNUMBER=21-296&SDesc=Surform%26%23174%3B+Plane+Type+%96+Regular+Cut+Blade
> 3) Sand paper
>
> I'm afraid I have no scientific answer to ensuring symmetry. I just put
> the plugs side by side and do a bunch walking in circles, taking
> measurements, and using a level. The plugs won't come out identical, but
> close enough to be functional. This part is more sculpture than science.
>
> - Next, paint the plugs with several coats of water-based paint. This is
> to prevent the resin from dissolving them. Water-based because if not you
> run the risk of the paint dissolving the foam.
>
> - Now apply layer after layer of wetted fiberglass cloth. I don't mean all
> in one sitting, I mean iteratively for about a month. There are two main
> considerations then, cloth and resin.
>
> I can't give you a specific recipe for cloth or the cost for cloth,
> because I used a combination of material I already had on hand and new
> stuff. I have purchased from http://www.fibreglast.com in the past, but
> this time found lower prices on eBay for what turned out to be perfectly
> good material. Mostly I used 6.5 oz (quite light) cloth so that it would
> drape better, but that depends on the shape of your tanks. For instance, on
> the inside face that goes against the hull, you can get away with much
> heavier material since its a gentle curve in just one plane, and the same
> goes for any flat surfaces. But if you have compound curves or tight curves
> its way more challenging to drape cloth without forming air bubbles. I make
> the walls that go against the hull thinner, since they aren't going to be
> banging against things like the outer or upper faces will. On average I
> probably put down ten to fifteen layers of cloth. The pros use vacuum
> bagging to prevent bubbles. With my caveman fiberglass skills I just try to
> avoid them in the first place by selecting better-draping cloth, and when I
> get a bubble I remove it with a flap wheel before putting down the next
> layer. In the middle of my layup I put down several layers of Kevlar. This
> material is trickier to work with than fiberglass, it can't be sanded and
> once cured you can only really go through it with carbide tools. The idea
> is to increase survivability by making the MBTs puncture resistant. If I
> hit a rock or a dock I still expect the resin might crack, but it should be
> quite hard to put a hole in the Kevlar. You might think this hard layer
> should go on the outside, but I put it mid-schedule so I could sand
> imperfections out of the fiberglass layers above it.
>
> This job (new sub, not Snoopy's tanks) took ten gallons of resin. Everyone
> will tell you epoxy is stronger than polyester resin. However, epoxy is $76
> per gallon vs. $34 for polyester, and Snoopy's polyester tanks have held up
> perfectly well for years. So, for me, this is a case of
> cheaper-is-sufficient and I went with polyester.
>
> - Iteratively sand and fix imperfections with a fairing compound. I used
> West Marine's #410 fairing filler (
> http://www.westmarine.com/buy/west-system---410-microlight-filler--P004_120_004_016).
> You can do this with Bondo as well, but #410 is easier to sand.
>
> - Dissolve the plugs. When I made Snoopy's saddle tanks the pink foam
> dissolved instantly with gasoline. This time, despite being the same brand
> foam it was somehow gasoline resistant, but acetone did the job.
>
>
> Best,
>
> Alec
>
> On Mon, May 4, 2015 at 9:22 AM, via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>>  Alec,
>>
>> I was curious if you could go into details about the making of your
>> saddle tanks?
>>
>> *Where did you get the foam and fiberglass and what types did you use
>> *How did you shape the foam to ensure symmetry
>> *Was there any difficulty or anything you would do differently
>>
>>
>> Thanks,
>> Scott Waters
>>
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>> Personal_Submersibles at psubs.org
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>>
>>
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