Working with fibreglass
From GTM Workshop
This is a draft article, please add to it!
Glass fibre is a strong workable material that can be used in the production of lightweight parts for your car.
Contents |
Glossary of Terms
Mould (not the sort you get in your bathroom). The mould is a robust cast taken from the plug (see below), it's used to create the final part.
Plug The plug is the "negative" of a mould, it's essentially the shape of the desired part. Made from plaster, fibreglass or body filler. If you wish to duplicate a part then the original part is the plug.
CSM or chopped strand mat is a mat of glass fibre strands help together by a bonding emulsion. The mat usually has no weave pattern and is easy to shape around corners and contours. CSM is available at various weights (thicknesses) depending on the application. As it's relatively cheap it's often used for the bulk of fibreglassing, however, not as strong as some other materials.
Resin is used in between glass fibre layers and bonds the layers together. It's usually (always?) activated by a catalyst that is mixed in as required. The mixed resin will cure quite quickly so only mix what you'll use in 20 minutes or so. Two types are in common use: polyester and epoxy, the former is the cheaper of the two but also the weaker. Epoxy resin is usually used in conjunction with Kevlar or carbon fibre for added strength.
Gelcoat is used for the outer or visible parts of the item and is therefore applied into the mould first. It forms a smooth water resistant outer, it can also be coloured with pigments added before mixing the catalyst.
Carbon fibre Carbon fibre is much stronger than ordinary fibreglass, when used correctly. This means that less resin is needed and therefore the resulting part is lighter, it's also much more expensive. Carbon fibre has an unmistakable appearance when used with clear gelcoats. It's not unusual to see carbon fibre used for the exposed parts to get the carbon fibre look without all of the expense.
Kevlar Kevlar is stronger than fibreglass but not as strong as carbon fibre, also it doesn't look quite as striking as carbon fibre. Kevlar can be used where strength is required but aesthetics is not so important, it can also be used to strengthen small areas of fibreglass parts, around bolt holes .for example.
Method
Plug Construction
skip this section if you are duplicating an already existing part
The plug is an exact model of the part you wish to acheive. Depending on the size and complexity of the shape then different methods of construction exist. A simple method is to create a basic shape with MDF, plywood or even cardboard and then build it up with modeling clay, plaster, fibreglass etc to the rough design, it can then be sanded back to the exact shape required.
Mould Construction
The plug is used to construct a mould from which to make the final part, alternatively an existing part can be used. This article assumes the former.
Coat the plug with a release agent...
The inside of the mould is as smooth as you require the final part to be and so is usually made from a good quality gelcoat. It's made by spreading the gelcoat over the surface of the plug and layering up fibreglass and resin until a strong durable structure is constructed, the plug is then discarded and the mould is used to fabricate the finished part.
Final Steps
Coat the mould with a release agent...
Construction of the final part is very similar to the mould construction, coat the inside of the mould with gelcoat and then layer up the fibreglass and resin. If desired, pigments can be added to the gelcoat to colour the final part as required.
Once cured you can remove the part, it should be the exact duplicate of the plug. The gelcoat can then be sanded for an extra smooth finish.
References
Related GTM Workshop Articles
External
Suppliers
- http://www.cfsnet.co.uk/ Glassfibre and epoxy supplier, they also have a series of projects and tutorials with advice.
- http://www.ecfibreglasssupplies.co.uk
Guides
- http://nd.essortment.com/sculptingtechni_rhun.htm
- Sculpting techniques for working with fibre glass
- http://www.mashie.org/guides/cfbalsa01.html
- Carbon Fibre - making a flat sheet for a computer case
- http://www.fgci.com/howto/ht003fiberglass_mold.html
- making a fiberglass mold
- http://www.fibreglast.com/contentpages-Mold+Construction-170.html
- Mould making
- http://www.garbled.net/tim/fiberglass.html
- Custom fiberglass without a mold
- http://personal.eunet.fi/pp/gsahv/dinghy1/simboii.htm
- Making a Portuquese Style Dinghy with fibreglass
- http://www.ecfibreglasssupplies.co.uk/store/laminating.php
- Laminating
- http://www.ecfibreglasssupplies.co.uk/store/making_moulds.php
- Making moulds
- http://www.ecfibreglasssupplies.co.uk/store/qualityingrp.php
- Quality in GRP
- http://www.ecfibreglasssupplies.co.uk/store/health_safety.php
- Health and Safety
- http://www.ecfibreglasssupplies.co.uk/store/tools_materials.php
- Tools and materials
- http://www.ecfibreglasssupplies.co.uk/store/reinforcedplastics.php
- Guide to Glass Reinforced Plastics
- http://www.ecfibreglasssupplies.co.uk/store/westsystem_user_guides.php
- WEST SYSTEM User Guides
- http://www.webbikeworld.com/t2/carbon-fiber-motorcycle-parts/
- Vacuum bagging
- http://www.cfsnet.co.uk/project-clearcast.html
- Clear Casting
- http://www.cfsnet.co.uk/project-resinrcast.html
- Resin casting
- http://www.cfsnet.co.uk/projects-speaker.html
- Car Boot Speaker Enclosures
