time to fully enclose my bike

[MisterInnovation]

Can't wait to see what you do next, I am doing a similar project on my bike, hopefully this will allow me to learn from your mistakes before I make them!

[visionary]

Originally Posted by bschloop

I have yet to order the fiberglass. the question is if I don't want to use chopped strand mat, should I buy lighter weight cloth and use more of it, or heavier cloth and use less? I probably won't be able to get more than one different roll due to shipping..

Now I see the images, here's my advice on the fibreglass. Firstly I would use CSM without doubt - reasons are that its cheaper, easier to work and more versatile than woven cloth. Woven cloth is principally used for parts that require better structural performance ie. loadbearing, due to the greater proportion of glass in the finished matrix. But this only becomes critical if you plan to use vacuum bagging, and highly rigid resin types. As a novice I would advise you to go the simplest route where flaws are easier to avoid and your finished product has the highest chance of success.
There is a lot of snobbery around woven materials and many people unfairly malign CSM but it is without doubt the most suitable material for your design. By the way I own a $2000 Recaro race seat made with CSM.
As for material weight, I advise 450g (or US equivalent) heavier mat is more difficult to work with and its principle benefit (faster build-up) does not apply to your design, since you do not need heavy, thick sections nor are you working against the clock in a fast moving productiion facility.
If you need further practical advice PM me and I'll record you a short video on my phone.
Best of luck, Pete

[bschloop]

MisterInnovation, I found your thread. sounds like a cool project. my advice is don't be afraid to make mistakes. Nobody ever made any thing without making mistakes first. if you want to see some of the things that did and didn't work for me, find my build thread from last year. I'm not sure how to link to it, but it ought to still be there, search for "2012 vetter build". lots of mistakes there to learn from.

[bschloop]

Pete, is that 450g/m2? over here they measure mat in weight per sq ft for some reason, while cloth is per sq yd. I did play around with some 6oz cloth yesterday, and found it to be too flexible even with 4 layers. is there any good way to get a smooth outer finish on csm? or am I just going to have to do a lot of sanding and filling?

[MisterInnovation]

Thanks loop! I LOVE LEARNING. I can never get enough of the stuff. I prefer to snort fist-fulls of it off of my desk when I get on forums like this. A simply astounding amount of information.

[3-Wheeler]

Originally Posted by bschloop

Pete, is that 450g/m2? over here they measure mat in weight per sq ft for some reason, while cloth is per sq yd. I did play around with some 6oz cloth yesterday, and found it to be too flexible even with 4 layers. is there any good way to get a smooth outer finish on csm? or am I just going to have to do a lot of sanding and filling?

Exactly!!

That is why I use a thin layer of foam between only TWO layers of 6 ounce glass.

Half the weight and about 8 times the strength!

Jim.

[visionary]

Hi Ben, some answers for you
Firstly about design, where you could make your life easier. Maximising strength without adding weight is best achieved using contours and returns rather than flat featureless panels. Next best method (based on strength/weight) is to bond (or glass in) a hollow rib section, like an automotive hood. Next best is to bond/glass in a foam core, and note that the benefit is derived from the section depth of the fibreglass not the core material.
Core material is not expensive but there are many alternative free sources that you could use.
On the CSM weight question, you are right, its metre squared in Europe. I’ve just checked a US site to help you convert but its quite complicated. Think that 6oz cloth as shown on this link
http://www.fiberglasssite.com/servle...%22/Categories
looks too lightweight for use as your principle material. The same site shows 18oz woven roving material which looks closer to the size I would suggest, but there is a disconnect in the weights since this site only has two weights of CSM (1.5 and 2.0oz) – puzzling!

Regarding the finish question - A topcoat will do what you want, but I have not used personally since all my work has been done from normal moulds. Here’s a link

Gelcoats & Topcoats, White Topcoat, - CFS Fibreglass Supplies

As a final note, my recommendation is that your panels only require a skin thickness of 1.5 – 2.5mm and this would be two layers of 450g mat, which I would suggest you do in two visits rather than rush one lay-up and compromise quality. Then release from your former (its not really a mould) and see how stiff it is. Bond on ribs and mounting blocks before doing the outer surface. I have a couple of other tips for you based on your images, if you need more help
Regards
Pete

[visionary]

Hi Ben, found you a link for comparison of US and metric materials
Chopped Strand Matting, CSM, 100g, 300g, 450g, 600g, 900g - East Coast Fibreglass Supplies
Pete

[3-Wheeler]

Originally Posted by visionary

....Fiberglass-Cloth-cln-6-oz-Cloth looks too lightweight for use as your principle material. The same site shows 18oz woven roving material which looks closer to the size I would suggest, but there is a disconnect in the weights since this site only has two weights of CSM (1.5 and 2.0oz) – puzzling! ....

Pete,

If the six ounce cloth referenced above is the same that I used, then 6 ounce material should be perfect for making a large motorcycle fairing.

I used one layer 6 ounce cloth over foam, on the tail of the car with very good strength.

Obviously, at mount points the layers of glass tapered up to five.

In my opinion 18 ounce glass is simply not needed for a light-weight glass/foam structure this size.

Jim.

[bschloop]

did some more playing around with fiberglass today. I made a sheet with three layers of 1oz/sq ft csm which is equivalent to two of the 1.5oz (450g), and one with 1/4" of polyisocyanurate foam sandwiched between two layers of 6oz cloth. the foam sandwich is stiffer, but it delaminated too easily. the foam failed under stress. the csm took more stress and returned to it's original flat shape. I think the polyiso foam is not as good as extruded polystyrene, but I don't want to have to buy epoxy if I don't have to. also the weight difference was minimal. I am working on plug #2 the left side. which will be a mirror image of the right.

on the issue of shape and using contours to add strength, I feel that any contours I add would negatively affect the aerodynamics of the fairing. the best shape is a very simple one. and should not be compromised for aesthetics, or even to increase rigidity. I can add ribs for that.