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 » Sat Aug 20, 2011 1:47 am

:cylongold: Fiberglass Lay Up Cont. 10


:cylon: Rigid mold prep, fiberglass reinforced epoxy (FRE) layup Overview-Page 19


At this stage closing the mold takes priority over everything else. The mold must be closed while the epoxy around the edges is soft, hardening epoxy could cause the PVA skin to separate due to tension stress. If the epoxy around the edges is really soft during the closing, the flanges will nicely align and the mold will clamp shut without any gap. This is a good indication that a perfect part is within. After the mold is clamped shut its time to clean up the epoxy tools.

[attachment=1]Tut 19.jpg[/attachment]



:cylon: Rigid mold prep, fiberglass reinforced epoxy (FRE) layup Overview-Page 20

As a final task for the soaked epoxy brush, set it on top of the mold. The brush is a timer, when the brush is rock hard stiff the mold is ready to open.

[attachment=0]Tut 20.jpg[/attachment]

That's the end of the tutorial and you can find the original post here at Ridgid N Soft Mold Tech (Fiberglass Lay Up)

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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Sat Aug 20, 2011 10:47 am

:cylongold: Demolding and Clean Up



This is the next chapter after you lay up your glass and resin and it has cured. Removing your part from your mold as so not to damage the mold or your part.


:cylon: Rigid mold part demolding and cleanup procedures.

Here we are going to open a rigid mold and remove the part inside, following a set of procedures to that ultimately prepares the mold for reuse. The FRE construction of the part inside was covered in the previous chapter.

[attachment=2]Demold Tutorial.jpg[/attachment]




:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 1

The epoxy has cured and now it is time to demold the new part. For this demonstration the bow mold is going to be used, the same method will be repeated later on the stern mold. Both molds were used for fiberglass reinforced epoxy part layup in the previous chapter. Tools are gathered for demolding, hex wrench, allen tool and tray for the bolting hardware. Straight slot screwdrivers of various sizes starting from tiny to small are needed, as are the chisel and the bucket. Not pictured but also needed is one or two exacto knives with chisel blades.

[attachment=1]dmc_01.jpg[/attachment]




:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 2

All the bolting hardware needs to be removed, this starts with loosening the hex nuts. Take a look at the top of the mold where the now hardened black epoxy was squeezed out when the mold sections were bolted together. The squeezing of wet epoxy usually finds it way into the bolt holes, temporarily gluing the screw in place. That is why the nuts and washers from the nut side are removed first.

[attachment=0]dmc_02.jpg[/attachment]

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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Sat Aug 20, 2011 10:58 am

:cylongold: Demolding and Clean Up Cont.


:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 3

With the nut and washer off the back side, the socket head bolt backs out just like it was screwed into a block. Refrain from using power screwdrivers to do this task until you are absolute certain use will not cause damage to the mold.

[attachment=1]dmc_03.jpg[/attachment]




:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 4

The bolting hardware has now been removed and placed in the tray. For now the mold is still held tightly together by the part inside, and the PVA mold release skin.

[attachment=0]dmc_04.jpg[/attachment]

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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Sat Aug 20, 2011 11:08 am

:cylongold: Demolding and Clean Up Cont. 2


:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 5

Using a power drill and the correct size drill bit, clear the holes of excess epoxy. In this case 6-32 screws are being used to bolt the mold, so a #29 (.136) drill is used to clear the screw holes. This task is best done when the mold sections are still together, insuring hole alignment.

[attachment=1]dmc_05.jpg[/attachment]



:!: Note: We do not use this method when casting the airplane parts as they come out of the mold pretty easy and the bigger your mold is the harder it is to use this water method. For smaller molds and parts this is a great technique to help you demold your part.


:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 6

This three gallon bucket is filled almost halfway with water. The PVA mold release solution is water soluble, so the mold will be opened underwater.

[attachment=0]dmc_06.jpg[/attachment]

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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Sat Aug 20, 2011 11:15 am

:cylongold: Demolding and Clean Up Cont. 3


:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 7

The mold should be completely under water when held down in the bucket. This is not quite the case here, more water needs to be added.

[attachment=1]dmc_07.jpg[/attachment]




:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 8

The demolding begins with the insertion of a very thin chisel blade between two section flanges. An Exacto brand blade is perfect for this, any similar type will also work. With the blade inserted a gap will open between the flanges. Put that gap under the water, then use a second blade to widen the gap. The purpose here is to allow water inside the flanges, where it will start to dissolve the PVA mold release solution skin. As the dissolving occurs, the mold sections will begin to separate. Do not try to forcefully separate the mold section. This will most likely harm the mold and the part.

[attachment=0]dmc_08.jpg[/attachment]

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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Sat Aug 20, 2011 11:19 am

:cylongold: Demolding and Clean Up Cont. 4


:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 9

The use of small standard screwdrivers is next to widen the gap made by the Exacto blades. The screwdriver blade is shaped like a wedge, the deeper the blade goes in the wider the gap in the flanges becomes. Keep the mold under the water during this process, you will actually feel the flanges give way as the PVA dissolves.

[attachment=1]dmc_09.jpg[/attachment]




:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 10

Now wide enough to put in the largest chisel blade, the screwdriver and Exacto blade on each side is falling out of the gap. At this point water has penetrated through these sections of the mold, separation will occur shortly.

[attachment=0]dmc_10.jpg[/attachment]

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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Sat Aug 20, 2011 11:23 am

:cylongold: Demolding and Clean Up Cont. 5


:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 11

The yellow mold section is just about to separate from the other sections. The side view shows the entire yellow section has detached from the part and is only holding together by the overflow epoxy on the opposing flange surface. Now its time to flip the mold to work on the second flange surface.

[attachment=1]dmc_11.jpg[/attachment]




:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 12

We have yellow section separation! The newly made glossy black bow part becomes visible for the first time.

[attachment=0]dmc_12.jpg[/attachment]

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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Sat Aug 20, 2011 11:27 am

:cylongold: Demolding and Clean Up Cont. 6


:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 13

With the yellow mold section removed, the part within becomes fully visible. During the layup process epoxy creeps into the miniscule gaps between the flanges. This is called "flash", and will be removed later. The mold is now ready to have a second section detached.

[attachment=1]dmc_13.jpg[/attachment]




:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 14

Flipping the mold to standing position, the blade chisels and the small screwdriver are working on one end to open a gap in the flange. Note that the entire mold is under the surface of the water, this way even opening the slightest gap in the flange allows water to start dissolving away the PVA mold release skin.

[attachment=0]dmc_14.jpg[/attachment]

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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Sat Aug 20, 2011 11:42 am

:cylongold: Demolding and Clean Up Cont. 7


:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 15

The second mold section comes off rather easily, separating away just after opening the gap on the end flanges.

[attachment=1]dmc_15.jpg[/attachment]




:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 16

Now repeating the gap opening procedure between the remaining two mold sections.

[attachment=0]dmc_16.jpg[/attachment]

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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Sat Aug 20, 2011 11:49 am

:cylongold: Demolding and Clean Up Cont. 8


:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 17

The third mold section is off the part and is resting at the bottom of the bucket where the PVA will continue to dissolve away. Once this point is reached there is no more use for the tools, removal of the final mold section needs to be done cleanly so no marks are left on the mold or the part. By gripping each side of the mold and flexing it, the final section will separate from the part.

[attachment=1]dmc_17.jpg[/attachment]




:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 18

The part is out of the mold and ready to be cleaned. Note the flash still attached to the part. Care must taken with the flash, it is sometimes sharp and can cut your hand. The part will have a slippery feel until it is washed and all the PVA solution is removed. To remove the flash, lightly run a chisel along the flash edge. Most of the flash will harmlessly break off. Whatever remains will be taken down with a file later on.

[attachment=0]dmc_18.jpg[/attachment]

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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Sat Aug 20, 2011 11:58 am

:cylongold: Demolding and Clean Up Cont. 9


:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 19

Cleaning the flash from the molds is the first step toward getting them ready for making another part. The Exact wide chisel blade is ideal for this task. Since the mold section have been in water just a few minutes earlier, the PVA is soft or dissolved. Slip the chisel blade under the flash and lift it away. The molds get washed in water to remove any remaining PVA after all the flash is remove, then they are ready to start again.

[attachment=1]dmc_19.jpg[/attachment]




:cylon: Rigid Mold Part Demolding and Cleanup Overview-Page 20

Two molds and two finished parts made in those molds. The molds have been washed and are ready to start the part making process again. The parts have been deflashed close to the skin, but no too close. There is a risk of scratch damage if flash removal is taken too far, too fast. Not to worry, the kit buyer will take slow and careful measures to make a satisfactory model.

[attachment=0]dmc_20.jpg[/attachment]

This concludes the demolding and cleanup chapter for rigid molds. Be sure to look at the previous chapters on materials and part making in rigid molds.

You can find the original post here Ridgid N Soft Mold Tech (Demolding Tutorial)

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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Sat Aug 20, 2011 12:43 pm

:cylongold: Vacuum Bagging


:cylon: Vacuum bagging (or vacuum bag laminating) is a clamping method that uses atmospheric pressure to hold the adhesive or resin-coated components of a lamination in place until the adhesive cures. (When discussing composites,
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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Sat Aug 20, 2011 1:35 pm

:cylongold: Vacuum Bagging Cont.


:cylon: Vacuum Bagging Materials

You will need some materials to preform the vacuum bagging technique. Bagging Material, Peel Ply, Breather and Bleeder cloth, Sealent Tape (Putty Tape), Bag Clips, Bag to Hose connecter, So let's start with this sample pack from Fibre Glast.


:cylon: Fibre Glast 4002 Vacuum Bagging Materials Sample Pack
4002 Sample Pack.jpg
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This convenient Sample Pack contains a 4" x 6" swatch of all of our vacuum bagging materials. It is ideal for determining which material you would like to try for your application. Plus, each Sample pack includes a coupon for $25 off your next order of $100 or more when purchased within 60 days!

Contains samples of:

Bagging Films

:arrow: #1678 Stretchlon
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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Sat Aug 20, 2011 2:56 pm

:cylongold: An Introduction to Vacuum Bagging Composites by Mike James, NextCraft Composites



:cylon: This next tutorial is by Mike James at Nexcraft and is an excelent to the point tutorial on vacuum bagging composite parts. You should visit his site here at Nextcraft where you will find this entire project and some real great info on making composite parts.


:cylon: An Introduction to Vacuum Bagging Composites by Mike James

I've been making plugs, molds, and hand layup parts since about 1990, but I'm relatively new to vacuum bagging. (2002) So, I'm not an expert, but will share what I learn, as I go. If you've done hand layup fiberglassing, but haven't tried vacuum bagging yet, I urge you to take the plunge. There's a little more preparation to do when making parts, but the results are lighter and stronger... and after all, that's what we're all searching for isn't it? Vacuum bagging is a much more consistent method of applying fiberglass to other parts, and/or molding fiberglasss parts in a mold, than any hand layup method, since the pressure exerted over the surface is uniform.

The concept is simple. Using a vacuum system allows all the excess resin to be extracted from your parts, during the early cure stages in your molds. Excess resin only adds weight and not strength, so this is good. The inherent nature of the process also produces a very nice finish on the interior or your parts, free of this excess resin, and suitable for gluing formers and other items in place. As a bonus, it looks much cleaner and more professional. Typical weight savings are average 25% or more. On a .60 -size model for example, it's the difference between 4 pounds and 3 pounds, for the fiberglass components. The process isn't terribly expensive, and it isn't terribly technical or difficult, so give it a try! Obviouslly, you'll need a vacuum pump, and these are easily obtained from all the popular composite suppliers. The other items are relatively inexpensive, and some are reusable.

[attachment=3]VB 1.jpg[/attachment]

Here are two virtually identical fiberglass canopies, made two different ways... (These are about 12 inches long, and about 6 inches wide.)

[attachment=2]VB 2.jpg[/attachment]

The canopy on the left was vacuum bagged. The canopy on the right was a hand layup. The vacuum bagged version has much less resin on the inside, (less shiny) and it weighs 25 percent less.


There are various ways to vacuum bag parts, and each method calls for a few additional things in the mold, aside from the fiberglass and resin. Here's an image, (below) courtesy of Fibre Glast Developments Corp., which shows a typical bagged layup.

[attachment=1]VB 3.jpg[/attachment]

This image shows a method of "bagging without a bag", meaning that the mold itself serves as half of the bag, and the bag material is sealed to the mold, around the flange. Of course, you could just place your entire mold inside a large bag and seal it, too. Personally, I haven't found it necessary to use "Flash Tape", and will show you how I've been doing it, a bit further into this article. After applying resin to the material in your mold, the other layers are immediately applied. As the pressure pulls the materials against your mold surface, resin will migrate through the peel-ply (without sticking to it) and into the breather-bleeder, which is often a material like felt. Resin won't stick to the bag either, so removing the parts later is easy.

There are a few details worth mentioning...
It's important that your "bag" is leakproof. This enables you to pull vacuum with a pump, then clamp the hose or shut off a vave, and still maintain vacuum inside the bag. If your system has leaks, then you must leave the pump on to keep vacuum. How long? It's important to leave your parts under vacuum until the resin has cured to the point where it's no longer being extracted through the peel-ply. If you're creating a glass layup like the one above, against a hard mold, the amount of vacuum pressure isn't critical. You'll see this as you make parts. Moderate to high pressures (say 20 inches of mercury) are fine. If you're vacuum bagging a skin onto a foam core wing, you'll want to use approximately half that pressure, to avoid crushing the foam. Again, this will be obvious as you make your first parts.

The peel-ply MUST extend across the entire perimeter of your part. If you don't do this, then excess resin around the edges will stick to the breather-bleeder, and you'll have a tough time pulling it off your parts. The breather-bleeder should generally go across the whole area too, but it's not going to screw anything up if you don't. In fact, you can use the placement of the breather-bleeder to selectively control where resin is removed. (See below for some tests I did using that method.)

I've found that it's better to pull the peel-ply and breather-bleeder from the part all at once, and then separate those things outside the mold. (before removing your finished part. If you try to pull the breather-bleeder felt away from the layup, it can be stubborn, and may pull your part away from the mold with it, possibly causing a crease or tear. Outside the mold, the two materials are easy to peel away from each other.

[attachment=0]VB 4.jpg[/attachment]

This canopy was my first vacuum bagged part, and is about as simple as you can get. I attached a vacuum fitting to an ordinary sandwich bag, and put the canopy mold inside. Using breather-bleeder felt only in the center of a part like this won't hurt anything, but... After doing some parts like this, I find that I prefer for the whole part to be equally dry, for a variety of reasons. Note that the peel-ply extends beyond the perimeter of the mold. If you do something like this, the resin will still get pulled away from your part, but will be stuck to the peel-ply. If you use breather-bleeder across the entire mold perimeter, then all of the removed resin will migrate into it, and you can use your peel-ply again.

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Re: Making Fiberglass Molds, Fiberglass Parts and Vacuum Bag

Post by Big Al » Sat Aug 20, 2011 3:19 pm

:cylongold: An Introduction to Vacuum Bagging Composites Cont.


VB 5.jpg
Here, I've made a very large bag, and placed multiple molds inside it, in an early test. Again, this test proved that it's better to have breather-bleeder material across the entire mold surface. This image shows what NOT to do.

When you prep your materials, make sure the bag has enough slack in it to conform to your parts. If your assembly is like the one in the image above, for example, make sure you cut the bag material large enough to allow for the depth of your mold, and trial-fit it before tacking the bag material down. The first time you make a part, this will be obvious, and it's easy to fix, if you make a mistake. You'll find it handy, when planning your system, to allow for a manifold of some sort, with multiple outlets. Because of the time it takes to prep any individual bag, it will help a lot if you can start one, prep another, come back later and shut off individual valves, etc..

If you are using a large bag as in the image above, with multiple parts in it, you may find that some parts are under vacuum, while other parts are not, due to the bag material itself creating "seals" between the various molds. This is easy to fix. Simply take some scrap pieces of breather-bleeder felt, and use them to "connect" the various molds. The breather-bleeder felt allows air to pass between the various molds, so that they all get equal vacuum pressure.

Like other laminating jobs, you'll need to use a slow-curing resin. The goal is to have time to apply the resin to your parts, assemble all the materials in the image above, and get it under vacuum before the resin has a chance to start to gel. So,cut and prepare all the materials above before you start applying the resin.

Imagine trying to remove all the excess resin from a mold like the one below, by scraping it, using rollers, paper towels, toilet paper, or whatever. You can do this if you're careful, but it's tedious, and when there are many corners in the mold, you risk pulling the glass away from the mold surface. This is actually a spot in the procedure where you can be "sloppy", with a vacuum system. Note how the glass is pulled down firmly into all the corners, in the fuselage mold top, below.

[attachment=6]VB 6.jpg[/attachment]

This particular mold doesn't have a suitable flange for sealing a piece of bag material to, so the entire mold was put in a big bag. All the glass is pulled into the corners, nice and tight.

[attachment=5]VB 7.jpg[/attachment]

Here's the bottom half of the same mold... a much simpler shape.

[attachment=4]VB 8.jpg[/attachment]

And here's the finished result. This is a very dry, light, and neat layup, thanks to the vacuum. The white spots at the rear edges are where I pulled the layup away a little bit after curing, to check it. No problems.

[attachment=3]VB 9.jpg[/attachment]

A small duct sample, much cleaner and lighter than would be possible by hand.

[attachment=2]VB 10.jpg[/attachment]

Here's a NACA inlet, almost weightless. A single layer of 4 oz. glass weighs about as much as a piece of typing paper

[attachment=1]VB 11.jpg[/attachment]

Here's a vacuum bagged wing tube socket. It weighs 2 tenths of an ounce, and is very strong.

Sandwich Core Construction
One of the basic concepts in composite construction is that if you can use a core of some kind, to separate your outer pieces a bit, you can increase it's strength and stiffness. Today, there are a huge variety of possible core materials you can experiment with, from some rather expensive synthetic foams, to something as simple as balsa. If you haven't tried this yet, you'll be completely amazed at how much difference a simple piece of 1/32" balsa can make on a molded part, for almost no weight gain.

[attachment=0]VB 12.jpg[/attachment]

Another product that would be difficult to keep light, by hand. This landing gear door is a glass/balsa/glass sandwich, and weighs 2 ounces. Thanks to the 1/32" balsa core, it's extremely stiff.

Refer to the J-47 "Eliminator 2" project to learn more.
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