Dreamin Hemi

Many of you have viewed my 50" mono deep V plug and mold build thread. [link=http://www.rcuniverse.com/forum/m_7292440/mpage_1/key_/tm.htm]50" Plug and mold build[/link] Here's a new thread to show in detail the processes that are taken once a mold is complete and your ready to make parts from it. All model boat manufacturers follow basically the same steps with minor variations, but essentially the same routine. I've posted a little on how I build a fiberglass boat, but nothing in detail. Have the time now to finally build one of my own boats for myself for a change. Will try to keep the wordage to a minimum and pictures to the max. Eventually you will see the entire process from laying the fiberglass to pulling parts from the mold, paint prep, color coat/clearcoat and hardware installation. Of course picts and video of this boat in action.

We'll start off with prepping the mold. Starting with mold wax, 100% carnuba. This stuff is hard to put on, and even harder to remove. This mold already has had 15 parts pulled from it and is very seasoned with about 25 coats of wax.

Once the wax is polished off, about 3 medium/heavy layers of PVA (plastic vinyl alcohol) are sprayed on with a detail cup gun at a pressure of about 80 psi which creates a very fine mist. PVA creates a barrier between the part to be created and the mold making it easier to release. Think of it like applying grease to a cake pan so it comes out easy.

Last picture is what the end result will look like. Hope you all enjoy!

Dreamin Hemi

Gelcoat layer. The final outer layer of the hull is actually the 1'st thing done when building a hull. Gelcoat basically is resin with a color pigment that is sprayed directly inside the mold before layers of fiberglass are placed, creating the final "paint" coat once the part is pulled.

The small dropper contains the hardner or activator used to harden the gelcoat. Typically 20 drops per ounce are mixed together and thinned slightly at less than 10% in order to be sprayed with my detail cup gun. 2 heavy coats are applied in the mold. Now we'll wait a couple hours as the gelcoat kicks and hardens.

Dreamin Hemi

The DCS is a seamless design so before the gelcoat completely hardens, I need to trim the edges that won't be used while still pliable. Makes it easier to pull form the mold as well when the time comes. The green that you see is the PVA that was sprayed on the sides to make this task easier. Not that it's even slightly difficult, as long as you do it early before it hardens completely. At this time, the gelcoat is more like flexable plastic, and trims very easily. Another hour and it will be too brittle to trim.

martno1fan

Nice pics mate i personally use masking tape on the flange saves using a knife or razorblades,i peel it off before it has time to dry seems to work ok.Are you planning on doing some hulls all gelcoat finnish rather than paint ?.
Mart

Dreamin Hemi

Masking tape still leaves a wavy edge, especially with gelcoat when pulled away. I totally perfer to razor trim this. Being that this is a seamless hull, a sharp razor cut edge will mate with the upper deck also trimmed in the same way much better than with tape. There are barely any gaps once they are joined in the mold.

As far as a gelcoat only hull, I doubt it since there is always slight bodywork to do when the halves are joined. Sanding, filling...thats what it takes to get this thing perfectly smooth and without any indications of a seam. You'll see before too long. Still can't beat a basecoat/clearcoat automotive finish.

sheograth

Nice pics, its fun to see the process

Paul M

You're a teacher aren't you?

It shows.

Well done. This is shaping up to be one of the better instructionals that I have seen. Keep *****g out on pics AND instructions. Don't leave anything out.

Thanks

Dreamin Hemi

Yes, it is very interesting to see. Events tonight are basically done in real time. Each time I finish a step, pictures are taken along the way and posted immediately.

Dreamin Hemi

Thanks, as you said, I am a teacher. High school shop/technical education instructor.

Dreamin Hemi

Have quite a few picts to post, but to make sence I'm breaking it up into sections.

Before you begin mixing your resins up, make sure you are ready for everything. You are given basically 20 minutes +/- of working time once you start mixing your catalyst with the resin. Having the fiberglass sized and pre-cut makes all the difference. Here I'm tearing the edges of the 1.5 oz mat leaving a frayed edge that will blend in to the other layers when I overlap the seam inside the lower hull. If the edges are not torn and just cut sharp, you loose strength and see an unsightly seam inside your hull. I normally overlap by 6" up from the bottom of the hull on each side so making sure you don't cut yourself short is important. Nothing like working the glass down and realizing your not able to run it all the way up the side[:@]. Ask me how I know.

The last picture shows a few things you will want to have in easy reach. Remember, the clock is ticking! Baby powder you ask? Keeps the sticky finger gremlin away.

Dreamin Hemi

Fiberglass mat can only bend so much and be worked so much before you start to affect the gelcoat (softens a little, possibly causing wrinkling or aligatoring). I mix some resin with microfiber untill it's the consistancy of applesauce. Using a tool I then work the catalyzed mixture into the strakes and corners, anywhere else I think may be difficult to work into with the wet glass. This creates a "filler" and allows the fiberglass to roll right over the corners and over the strakes without any air pockets or bubbles.

Notice in other pictures you may see a fan I keep in the window. This exhausts the resin fumes and powdered fiberglass as I'm mixing to the outside and not in my immediate work area.

Dreamin Hemi

Here is where the fun begins. Start out by mixing resin and catalyst to this time 10 drops per ounce. Here I use 9 oz disposable cups that has exactly 8 oz of resin. Count out 80 drops for this cup, mix for about a minute. I then use a disposable brush and spread out the poured resin directly over the gelcoat, smoothing out my applesauce glass mixture making sure no air pockets sneak by. Using about 6 oz of resin, I create a thin layer that the mat can stick to once I lay it down.

Dreamin Hemi

Once your have a even coat of resin covering the mold, time to pick up your mat and lay inside. Using your hands at first, position the mat so that you overlap the middle by 6" for this hull. Notice the torn edgs are INSIDE the hull? Using a trim roller and roller pan of resin, apply a generous amount of resin directly to the mat enough to soak and remove air bubbles. I start with the middle usually and work my way to the sides and up rolling in all directions once it's down, this helps break up the microscopic little strands creating a much stronger bond than just wetting out. You will use lots of resin with this step, I think almost 16 oz was used for the mat lay up. Mat is easy to work and tool around corners, can be stubborn sometimes, but usually a little more resin can convince the mat to listen. Again, watch for air bubbles, especially in the corners.

The third picture shows only 1/2 of the mat installed. The last 3 pictures shows that I overlapped my prevous layer creating 2 solid layers for structural strength of mat. Notice how quickly the roller wets out the fiberglass with just one pass. I'm using a 1/4 inch nap roller for this job.

Dreamin Hemi

As soon as the mat layer is wet and rolled out, I apply a 2'nd and final layer of 7 oz cloth directly over my mat. This part is done in one piece from the middle outward. Typically the roller is still saturated with resin and the wet mat underneigh the cloth is enough to wet out the fabric. This job required me to quickly mix 6 oz more resin to finish out the job. Notice the pre-poured and measured out cups of resin in earlier pictures? Tick-tock!

So far this lower hull layup has gone smoothly. Have my required layers, overlapped, seams blended, rolled out and checked for air bubbles with a disposable brush in the corners. Of course I can't forget my logo decal sandwiched between the layers of glass. Hull #16.

At this point, I had to wait untill the resins have kicked off (began to harden) and be solid enough for me to trim my edges once again.

Dreamin Hemi

Keep in mind than this is a totally seamless hull design. Once the upper deck is mated to the lower, you will not see the seam at the attachment point. No overlapping shoebox, or lip will be on this design.

Once the resins have hardened, but still sort of soft, I trim with a carpet knife using my mold as the guide. Keeping the knife perfectly flat and taking my time makes for a perfect fit once it comes time to join the two halves. I need to be cautious as to not separate the gelcoat from the mold while cutting, so cutting only from the inside of the hull, with the knife angled in the direction of my cut, I can easily apply pressure to the sides of the hull making sure no separation occurs. If you wait too late to trim, the fiberglass will be rock hard and take forever to trim evenly. Not to mention possibly breaking the gelcoat/mold bond.

And there you have it. One lower section of my Dreamin' CS hull finished and waiting for the next step...engine rails.

Just the upper deck and hatch need to be done in the same fashion to complete all the fiberglass parts of this boat.

More to come.... Daylight gone now and a weak flash makes for not so great pictures. Will add better picts tomorrow night as the engine rails get started.

doomracing

way cool looking forward to seeing it all come together.

GRANT ED

Awesome thread. Keep them pics comming.

Dana W

Nice job Scott . Try using a 1 oz mat & a 5.7 cloth you'll see it'e way easier and your boats come out lighter and because of the details in your boat the stength is still there .

Paul M

Do you ever have any trouble cutting your mold with the knife as you trim the edges? If this is an issue, how do you guard against it?

martno1fan

Why use cloth at all? just use mat its stronger than cloth anyway ?,mat is also cheaper than cloth.Sure cloth looks nicer on the inside but you can get a reasonable finnish just using mat in my opinion.Have to say i havent had any problems using tape to get a straight edge when gelcoating so far and as you say you need to fill and sand the seam anyway so it makes little difference especially if your painting the whole boat too.
Mart

Dana W

Mat is stronger then cloth ??? I don't think so . Try ripping cloth . Mat is your body , cloth is your strenght .

Dreamin Hemi

I haven't had a problem trimming yet. One of the reasons I use a carpet knife is the flexability of the blade and the sharpness. I can apply the proper pressure to make my trimmings right along the mold edge perfectly flush and never cut into the molds tooling gelcoat. I have nicked the gelcoat before, but only when I was using a stiff utility blade.

Dreamin Hemi

I use my materials based upon my experimentation with them over the years in the hobby world and autobody work I used to do. Also for the same reasons Dana has mentioned above. Matter of fact, after speaking to Remy at Aeromarine, (lives down the road from me), I'm thinking of just using 2 layers of 6oz cloth only once I run out of my mat supply, and keep the mat for mold construction. Definately woulden't use nearly as much resin and will save lots of weight using cloth only. Currently designing a race boat plug that may use this lay up exclusively. The DCS is basically a "Sport" boat that does weigh a little more than a race hull normally would, however the little extra weight seems to help performance in the rougher water, just as I intended.

martno1fan

Im basing my comments on what i was told by a glass supplier asuming your using plain weave cloth?,i supose it depends what cloth your using as there are lots of diff ones ,plain weave cloth def wouldnt add much strength .That said i dont see any benefit in using the really expensive stuff and then using cheap polyester resins.If you use epoxy then sure i can see using more expensive cloth might be an idea as regards weight saving.I wouldnt make a race boat from polyester resin full stop personally,far better to use epoxy as it will allow for a lighter layup and last a lot longer as it wont twist over time like polyester will.How about some video of your boat running ?.
Mart

Dreamin Hemi

Patience grasshoppa! Vids will be the icing on the cake for this thread.