Making a Small Mold

There are many methods and materials that can be used for making a fiberglass composite mold.

I found a video from Eastbay Composites that demonstrates a method for making small molds in a very quick an inexpensive fashion.

As you see from watching this, the basic construction materials are tooling gelcoat and inexpensive bondo for the support structure.

This mold construction technique certainly has drawbacks, but also has several advantages.  None of the materials required spray equipment, which is messy.  Brushes are inexpensive and easily disposed.  A disadvantage of this method is that surface finish might suffer from a lack of consistency on the coating thicknesses for the gelcoat and the release agents.

Using bondo as the support structure is quick and easy compared to glass and resin, but can cause problems as well.  It is more likely to crack, and can warpage issues as it cures and may be hotter in some areas than others.  Bondo may have some difficulty maintaining dimensional tolerance as it shrinks during cure.  Industrial resins used to create molds have minimal shrinkage in their chemistry and are placed on slower to minimize heat from the chemical reaction.

For quick, inexpensive and easy parts, this method from Eastbay Composites may work well for you.  What has not been discussed yet is that the mold model can be the most difficult part.  Off the shelf items are easy, but custom ones may be difficult.  Creating a shape or surface is time consuming and tenuous.  After that is complete, you can make your mold and final production parts!

Fiberglass Pool Installation

Fiberglass swimming pools have several advantages as compared to other types, such as concrete in-ground pools, vinyl-lined pools, and above-ground pools.

-They can be built off-site in a controlled environment.

-They are lightweight for transport and lifting into place.

-They have a durable and usually have a one-piece design.

-The material allows for design freedoms that are more difficult with other materials.

The many advantages of fiberglass swimming pools in residential use are numerous.  They do have disadvantages as well, just like other materials.  The outdoor environment can be very tough on any fiberglass structure.  Proper cleaning and maintenance is very important to keep an appropriate appearance together.

Fiberglass pools can be easily delivered on-site with medium-duty shipping equipment and lifted in place with a crane.  I found a great Youtube video demonstrating a lift over a large two-story house.  The pool easily goes into place, ready for surrounding landscaping.

Cirrus Composite Airframes

I found a very interesting Youtube peek inside of the Cirrus airplane assembly factory in Minnesota.  While it would be cool to learn more about the actual composites fabrication of the individual parts, there is some great information about part bonding, inspection, and final assembly of the Cirrus aircraft.  They use fiberglass and carbon fiber reinforcements to create a very strong and durable fuselage, and it is great to see in action.

Personal jets made of composite materials offer many advantages and unique properties.  Design of complex shapes and anti corrosion of aluminum are two advantages.  Disadvantages include repeatability and upgrading/modification.

Composites that are properly designed and fabricated can be used in many applications where safety is a big concern.  Proper design and inspection during production can create an airplane that can be easily maintained and have a very long life.

Great factory tour courtesy of Aero-TV:

Infusion-Test Panel and Fuselage

Ran across an interesting Youtube video demonstrating an epoxy resin infusion process on some test panels and fuselage.  It is interesting how everybody has their own terminology and technique for resin infusion.  There is definitely more than one way to get the job done.

They use an interesting layup, including lots of the Soric material.  I have used this before, and it is a good material to infuse with.  Made by a company called Lantor, it is a non-woven polyester material that acts as a core material.  It appears that the folks in the video are using the SF grade Soric, which comes in several thicknesses.

An advantage of using Soric as a core is that it flows resin very well for infusion.  It is easy to cut and handles well.

Disadvantages also abound.  One of them is the possibility of print-thru on the surface of the laminate.  Another is the negative effect on the structural properties of the laminate.  This non-woven material does not have much crush resistance such as a balsa or foam material.  A serious issue that I have found is the higher risk of delamination.  Like any core, this material works by separating the two skin layers to create a sort of “I beam” effect.  The problem is that this material is not inherently strong within itself.   Though it does become saturated with resin during a proper infusion, it is not nearly as strong as glass or carbon fiber reinforcement.

As the video demonstrates, a proper resin infusion can look easy.  With proper materials, practice, and knowledge it can be.

Vacuum Bagging Video

Vacuum bagging is a process that requires unique materials and processes, but can be simple to operation in an ongoing basis.

There are many advantages to vacuum bag molding, a few of which include:

• Improved resin/glass ratio
• More consistency across the laminate and part -to -part as compared to open layup
• Containment of air emissions from the resins

As compared to hand layup and chop layup, there are a few disadvantages, including

• Higher consumable material cost
• Higher capital equipment cost
• Difficulty with superior surface finish

Some parts are more suitable for vacuum bag molding than others.  It also depends upon which process it is being compared with.

Vacuum bag molding requires an extremely tight seal between the mold and the bag.  Molds with multiple pieces or holes for inserts can be difficult to complete a seal.

Parts that are overly large and complex can present challenges with placing resin and reinforcement before the cure cycle starts.  The bag must be completely sealed and under full vacuum before the curing cycle of the resin begins.

The basic premise of vacuum bag molding is that the air is removed from the bag, allowing the atmosphere (air on the outside of the bag) to push the bag onto the part on the mold, compressing the layers of resin and reinforcement.  Many misinterpret the process as “sucking the extra resin out.”  We are merely allowing the laminate to be compressed by the weight of the air above us in the atmosphere to consolidate it before cure.  The excess resin is usually absorbed by extra layers of sacrificial material inside the bag.