Hi there,
I am a student and as part of my final year I am creating a prototype of my design project. The design includes 4 HDPE rotationally moulded sections, however I will not be able to manufacture these for my prototype so have decided to use Plywood and Polyurethane Foam to create moulds in which I will cover in fibreglass.

I have never worked with fiberglass before and have watched a fair few video tutorials on laminating with fiberglass but was wondering if anyone could give me some advice more specific to my project.
I am looking to lay up around 3mm of Fibreglass but am wondering what type of Fibreglass I should use (CSM or Woven Glass Fabric, combination of both?), how many layers and what grammage of sheet would be best to use? Also I have struggled to find a tutorial on how to apply a final layer which would provide a smoother finish to the outside of the parts (Would using a Gel Coat be possible or just a thin layer of Fiberglass to be sanded to achieve the required finish?)

Some things to note:
I know that I need to use Polyester Resin.
I have watched a tutorial on laminating onto plywood which talked about the need to soak the plywood in resin first before layup and the need for radiused edges for the Fiberglass to form properly to the mould.


Above image is the four parts that are being created. Rough Dimensions are:
First Section = 520mm (W) x 600mm (L)
Second Section = 520mm (W) x 300mm (L)
Third Section = 520mm (W) x 150mm (L)
Fourth Section 520mm (W) x 200mm (L)


Above and below images are the current progress of some of the moulds yet to be sanded and shaped properly.


Any help is much appreciated!

Cheers,

Ross

Which fibre glass depends on your priorities.  Does it need to be strong? light? Or is it just a show piece?

Remember that adding fibreglass in layers will take off any sharp contours unless you take special care to lay up and sand/shape the fibreglass to retain the shape.

A good overall combination would be to build up most the thickness with 450gsm CSM then a couple of layers of 100GSM on the surface  and a final  layer of  100gsm woven cloth. That should give you a  reasonably smooth surface from which to work.   Remember polyester cures tacky.  I would sand the surface then apply a couple of layers of XCR Epoxy Coating Resin then sand and polish to give a good finish or paint it .


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

For 3mm probably about 4 layers of 450csm and then your final layers on top.

You can pigment all of your resin if you so wish as long as you use a pigment compatible with the resin system you are using.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant