Making Fiberglass Molds, Fiberglass Parts and Vacuum Bagging

A lightweight, extremely strong, and robust material. Info on working with it, making molds, fabrication of parts and more. The info is not specific to Classic Cylon Centurions, but SURE can be helpful for them and many, many others projects. Here you'll find various threads with great info from our members for the hobby of costuming.
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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Mon Aug 15, 2011 8:41 pm

groupleaderzeta wrote:If you drop it and it bounces, its soft. if you drop it and it leaves a hole or explodes in millions of pieces, then it hard.

:grin:

That's Funny :nah: :nah:


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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Mon Aug 15, 2011 10:06 pm

:cylongold: Making a Fiberglass Mold


:cylon: I have learned and executed this process under the Qui Gon Jin like guidance of my great friend Steve Nickerson. I am no expert by any means and I am stricktly a hobbiest. I don't have any pics of the molds we built but I do have the plug and a molded airplane so I will share those pics later.

When I wanted to learn how to do this process it was very hard to gather information on how to do it. There are bits and peices everywhere and mostly on how to repair or build boats and some automotive. So to learn how to make the parts I wanted, I had to spend hours scouring the net for the information.

Everything I slap up here is information and sites I found when I was Scouring and learning how to do this.

This process allowed us to start by making molds for small parts all the way to making an entire molded plane with true laminar flow wings.

( :salute: We Made some very slippery airplanes!!) :cool: Very Cool process, here it is in breif:

You make a plug, You make a mold of the plug from fiberglass, You make a fiberglass part with your fiberglass mold! :nah:

:cylon: "And Parts is Parts!" :cylon:




:cylon: This is the first artical I started with. it's a tutorial on making a cowl mold and it came from The Composite Store another supplier of everything Fiberglass. they gear for the airplane hobbiest but glass and resin, is glass and resin.

:cylon: Tutorials by CST

Making a Fiberglass Mold PDF

Molding Fiberglass Parts

CST Home Page


:cylon: Making Fiberglass Molds

Fiberglass molds are commonly used to make multiple copies of a part which may have a complex shape. Some of the advantages of using a fiberglass mold are: they are easy to make, the materials are inexpensive, they will last for many years and can be used to produce hundreds of parts. The process starts with a pattern that you wish to copy. In this case I have started with a vacuum formed cowl from a model kit. This is a common part that any modeler may want to copy in fiberglass. The pattern could also be shaped from balsa or foam and finished to achieve a glossy surface.

[attachment=1]Cowl mold Original.jpg[/attachment]


:cylon: Step 1

First you must decide how many parts you will need to divide the mold into, in order to easily lay up the parts. In order to remove the rigid parts from the mold, you must have a positive relief angle on all the mold parts. This means that the mold cross section must get wider as you go from the deepest part of the mold to the outer edges. For these reasons and because this pattern has a seam horizontally dividing the cowl, I decided to make a two part mold dividing the mold along the pattern seam. The parting surface of the mold defines how the multiple parts of the mold will fit together. This surface is created by building up a parting board that divides the cowl shape in half.

[attachment=0]Cowl Mold 1.jpg[/attachment]

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Last edited by Big Al on Tue Aug 16, 2011 2:43 pm, edited 3 times in total.
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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Mon Aug 15, 2011 10:50 pm

:cylongold: Making a Fibeglass Mold Cont.


:cylon: Step 2

The parting board is simple, a few scraps of balsa wood glued together to form a U shaped partition that fits over the cowl. In order to achieve a smooth glossy surface on the mold, a piece of .014 Mylar is contact cemented to the balsa scraps. Similarly the mold surface along the back edge of the cowl is defined with a scrap of foam and a sheet of Mylar. The cowl pattern and the parting surface forms are held in place with Chavant modeling clay on the back of each surface.

[attachment=1]Cowl Mold 2.jpg[/attachment]


:cylon: Step 3

Around the edges of the cowl pattern the small openings must be sealed. This can be done with modeling clay by pressing clay into the corners and openings then trimming away the excess material with a model knife or razor blade. In this case, the light weight plastic pattern can be distorted if you press to hard. So be careful that the intended shape is preserved.

[attachment=0]Cowl Mold 3.jpg[/attachment]


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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Mon Aug 15, 2011 11:35 pm

:cylongold: Making a Fiberglass Mold Cont. 2


:cylon: Step 4

After all the excess clay is removed, the surfaces of the pattern and parting surfaces must have mold release applied. It is important to apply both Partall mold release wax and a liquid mold release. The Partall wax is applied by wiping on a layer waiting a few minutes for the wax to harden then buffing off the surface to a shine. The waxing is then repeated; the number of times will depend on the surface. If you have a glossy completely smooth surface like the Mylar plastic, two or three coats of wax will be enough. However if the surface has any potential for porosity or tiny bubbles in the surface finish, up to ten coats of wax are needed. These layers of wax will fill the tiny surface imperfections. If you have any doubt about the surface, add a couple more layers of wax. The epoxy will lock into these imperfections if you don't use enough wax. Then apply a complete layer of liquid mold releases. I recommend the Safelease products as they can be wiped on with a cloth and dry in about 30 minutes.

[attachment=1]Cowl Mold 4.jpg[/attachment]


:cylon: Step 5

Now you are ready to start applying the layers of epoxy and glasscloth. Use the following West System materials: 105 Resin is a low viscosity resin that easily wets out the cloth and allows you to minimize air bubbles between cloth layers. 205 Fast Hardener allows you sufficient time to wet out each layer, then gels up quickly so that the mold building process can be completed in a few hours. 406 Colloidal Silica Filler is used to thicken the epoxy system to aid in applying epoxy to vertical surfaces and filling corners and details in the mold. 423 Graphite Powder is used to give the tooling gel coat layer of the mold a black color and a harder surface.

[attachment=0]Cowl Mold 5.jpg[/attachment]


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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Mon Aug 15, 2011 11:45 pm

:cylongold: Making a Fiberglass Mold Cont. 3


:cylon: Step 6

The black color is important when wetting out glass against the mold surface because air bubbles and dry places in the glass are white while the properly wet out glass is transparent showing the black surface. The high contrast makes it easier to produce high quality parts. Mix tooling gel coat from West System 105 Resin with 205 Hardener and about a teaspoon of Graphite Powder. Then stir in a little Colloidal Silica to get a mixture that has the viscosity of ketchup. You need to be able to brush on a thin layer, (.010" to ,020") and have a mixture that will stay on the vertical surfaces. Begin by brushing a thin layer in all of the corners. Be careful to not trap any air in the corners as you apply this layer, this is a common problem particularly if you mix the gel coat to thick.

[attachment=1]Cowl Mold 6.jpg[/attachment]


:cylon: Step 7

Now apply the gel coat layer over the remainder of the surface. Next mix a little more Colloidal Silica into the resin in the pot to increase the viscosity. Apply some additional gel coat to the corners of the mold to fill in any small radii corners. It is difficult to wet out the glass cloth and keep it in corners of less than 1/4" radius. By filling the corners now you are making the glass application easier.

[attachment=0]Cowl Mold 7.jpg[/attachment]
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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Mon Aug 15, 2011 11:54 pm

:cylongold: Making a Fiberglass Mold Cont. 4


:cylon: Step 8

Use a coarse weave glass to lay up the mold. I recommend CST style G3733 glass, it is about a yard square. It wets out easily and builds up thickness more quickly than lighter materials. If the mold has a complex shape like the cowl mold we are building cut the glass on the bias so the fibers run on a diagonal and cut the material into strips 2 to 3 inches wide. This way the cloth will stretch and distort as needed to follow the surface.

[attachment=1]Cowl Mold 8.jpg[/attachment]


:cylon: Step 9

Let the gel coat layer of epoxy set up for about 30 minutes. The epoxy should have set to the point where the surface is only a little tacky. Now mix up another batch of West System Epoxy 105/205 and brush a liberal layer on top of the gel coat layer and begin laying strips of glass on the surface. Whenever possible, apply the epoxy first then lay the dry cloth down. This wets out the glass from the bottom displacing the air in the fabric with less chance of trapping air under the layer of fabric.

[attachment=0]Cowl Mold 9.jpg[/attachment]

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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Tue Aug 16, 2011 12:22 am

:cylongold:Making a Fiberglass Mold Cont.5


:cylon: Step 10

Continue wetting out strips of fabric until you have at least two
layers of cloth over the entire surface.

Now let this layer set up for about 30 minutes just as you did the gel coat layer. The curing time between layers is not critical. It must be long enough for the epoxy to gel and be only slightly tacky as a minimum and short enough that the epoxy is not nearly cured. So something between 30 minutes and 4 hours will work for a 70 degree shop temperature.

[attachment=1]Cowl Mold 10.jpg[/attachment]


:cylon: Step 11

Because the mold will need to be strong and rigid, we need to build up the thickness of the mold. An easy way to do this is to add a layer of Coremat. It is about 1/10 inch thick and can be easily cut to any shape. Cover most of the area with Coremat or a thin chopped strand mat could also be used. Wet this layer well and let the epoxy set up for about 30 minutes then apply another layer of glass cloth as you did previously.

[attachment=0]Cowl Mold 11.jpg[/attachment]
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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Tue Aug 16, 2011 12:36 am

:cylongold: Making a Fiberglass Mold Cont. 6


:cylon: Step 12

Set the mold aside and let it cure overnight. The next day remove the vertical parting board that the vertical surface of the mold was built against. Clean up any clay that may be left on the pattern.

With a Dremel tool and a 1/4 inch ball cutter, cut four small recesses into the vertical parting surface corners about 1 inch away from the pattern. These will key the second half of the mold into the first half. Now repeat steps 6 through 11 above to build a second half of the mold against the first half. Mold release, gel coat, glass cloth, Coremat, glass cloth and let it cure overnight.

[attachment=1]Cowl Mold 12.jpg[/attachment]


:cylon: Step 13

The next day remove the foam base and Mylar layer from the aft edge of the cowl. Then use a Dremel tool with a reinforced cut off wheel to trim all the rough edges off of the molds. Now carefully separate the mold halves. You may need to use a model knife in one corner to start separating the molds. Twist the knife a little then put a thin strip of wood or plastic in the space and run it around the mold to separate the halves. The mold is now completed and you are ready to start molding fiberglass cowls.

[attachment=0]Cowl Mold 13.jpg[/attachment]
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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Tue Aug 16, 2011 12:42 am

:cylongold: Making a Fiberglass Mold Cont. 7


:cylon: Supplies to complete this project:

Molding Supplies:

:arrow: Mylar 0.014
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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Tue Aug 16, 2011 1:20 am

:cylongold: Molding Fiberglass Parts


:cylon: This is the next tutorial after you make your mold is to make a part.



:cylon: Molding Fiberglass Parts

Apply mold release to all the surfaces of the new mold. If this is your first mold, it is likely that you will have some small air bubbles in the corners. These must be filled with the mold release wax. Make sure that all surfaces are covered, including the edges and back of the mold with a few coats of wax. When you are making parts the epoxy can go everywhere and this makes it easier to clean up the mold. Use many coats of wax. If you need a number that will work in all cases, apply ten coats of wax. Then apply a liquid mold release to the mold surface.

[attachment=2]Molding 1.jpg[/attachment]


:cylon: Step 1

Use the same West System Epoxy that was used to build the mold for the parts. Mix up a small batch of West System 105/205 for the gel coat layer, and brush it over the mold surface. If you have any small radii corners in the mold, mix a little 406 Colloidal Silica Filler into the remaining epoxy and fill these corners. Glass cloth will not stay in these tight corners and as it pulls away it will pull in air to form a bubble.

[attachment=1]Molding 2.jpg[/attachment]


:cylon: Step 2

Let the gel coat layer set up for at least 30 minutes. It should be slightly tacky to touch.

Now cut a piece of glass cloth. For this type of part I recommend CST style G3733 cloth. The cloth should be cut on the bias because of the many tight corners. Also in the corners at the front of the cowl, cut the cloth diagonally into the corner, to allow the fabric to overlap.

[attachment=0]Molding 3.jpg[/attachment]

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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Tue Aug 16, 2011 1:27 am

:cylongold: Molding Fiberglass Parts Cont.


:cylon: Step 3

Wet out the surface of the mold with a coat of epoxy and lay the dry glass into the mold. Start pushing the cloth into the epoxy at the deepest corner of the mold and work out from there to press all the cloth into the epoxy. Use a disposable epoxy brush and push the cloth down with the end of the brush. Dry spots will appear white against the dark mold. Add more epoxy as needed to wet out the cloth completely and eliminate all air bubbles.

[attachment=1]Molding 4.jpg[/attachment]


:cylon: Step 4

Wet out the cloth in the mold completely extending about 1/4 inch past all the edges of the mold. Let the epoxy cure for at least 45 minutes this time. When you trim off the excess glass the epoxy must be cured to a solid yet flexible stage. If you get gummy epoxy on the knife blade when you start trimming the edges, wait another 15 minutes and try again.

[attachment=0]Molding 5.jpg[/attachment]
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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Tue Aug 16, 2011 1:39 am

:cylongold: Molding Fiberglass Parts Cont. 2


:cylon: Step 5

Use the edge of the mold as a guide and trim off all the excess glass around the parts. If the blade is sharp and the epoxy is cured to the right stage it, should cut easily.

[attachment=1]Molding 6.jpg[/attachment]


:cylon: Step 6

Now is the best time to join the parts. Clamp the mold halves together then wet the inside surface of the parts along the seam with epoxy. Cut a strip of cloth and apply it to the inside of the seam. For the cowl I cut a bias strip of the same fabric used to mold the parts. In the case of a long narrow part like a fuselage, glass tape is easier to use for joining. Again trim off the excess glass after it has cured for about 45 minutes.

[attachment=0]Molding 7.jpg[/attachment]

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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Tue Aug 16, 2011 1:50 am

:cylongold: Molding Fiberglass Parts Cont. 3


:cylon: Step 7

Let the cowl cure overnight before you remove it from the mold. Start at one corner and separate the mold halves with a model knife. As soon as the corner starts to open use a thin strip of wood or plastic to open all the edges of the mold. Now carefully remove the part from the mold.

[attachment=1]Molding 8.jpg[/attachment]


:cylon: Step 8

You now have a fiberglass part that is an exact duplicate of the pattern. It
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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Tue Aug 16, 2011 12:14 pm

:cylongold: How to Mold Fiberglass and Composites Tutorial Videos


:cylon: These videos were made by Fibre Glast and is one of many tutorials they have on Fiberglass mold and parts making. The videos were made some time ago and the girl who narrates them is kinda droll but hang in there and watch them all :nah: Lots of good info here.



:cylon: Instructional Videos

A Step By Step Guide To Molding Fiberglass. A simple introduction to fiberglass mold construction; explained using a model aircraft cowling. From plug, to mold, to finished fiberglass part.


:cylon: Video 1 of 8




:cylon: Video 2 of 8




:cylon: Video 3 of 8




:cylon: Video 4 of 8




:cylon: Video 5 of 8




:cylon: Video 6 of 8




:cylon: Video 7 of 8




:cylon: Video 8 of 8






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