Making your own fairing parts
Introduction
To make GRP (glass fiber reinforced plastic) copies of most fairing parts is
quite possible for a reasonably handy person. Does your friend have an undertray
or a hugger that you like...?
For me it started when the road turned left (but I didn?t). The cost of replacing
the fairing parts was not small, to put it mildly. This was before Internet
(for me), so I let Mr. Honda grab all of what was in my wallet, and then some.
I couldn?t have any more of that, so there was only one thing to do to make
my own plastic parts in the future.
I chose to do this "how to" on the simplest shape on the bike - the
seat cowl. The pics are small and distorted to fit the pages and limit file
size and should be considered as illustrations.
Good luck! /Swiffer a.k.a. U-Joppe
Overview of the contents
What do you need?Evaluating the part to copy (the plug)Preparing the plugMaking the mouldUsing the mould to make the new fairing part.SummaryThings to know about polyester / comparison between polyester and epoxi1. What do you need?
Wax and maybe rubbing to make the original shiny. I use rubbing,since the surface was a little coarse. If your surface is really clean and
nice, wax will do.
Releasing agent Typically polyvinyl alcohol, get it in a boat supplyshop!
Polyester, the resin I use. May as well be 2 component epoxy (see.Discussion at the end).
Gelcoat for the outer layer in moulds and, if you choose, the fairingpart.
Hardener for the gelcoat and the Polyester Glass fiber Non-woven (chopped strand) mats are good enough for amould. When I make the fairing part I may use woven mats that, weight for
weight, are stronger.
Jars to mix polyester and hardener. Glass jars are good but, whenI do a lot of jobs, I run out or just dislike to thow away so many (can?t
recycle with plastic in them...), then I use old plastic jars. However, all
plastic cups won?t do, those made of polystyrene will slowly "melt"
(but may still work if you work fast enough). The hardening process is exothermic
(produces some heat) so, if you mix way to much, make sure that the remaining
unhardened plastic is placed safe and in something that will tolerate the
heat.
Brushes/Paint rollers To apply polyester and release agent and alsoto work the polyester into the fiber mats. I wash them in acetone so I only
need one of each.
Mask that filters organic vapors Not just a dust mask. Polyester/styrenevapors are not good for you (You can trust me on this one ? I?m a toxicologist)
Plastic gloves I use dishwashing rubber ones or cheapo single useplastic gloves. You do need to use gloves ? see 12 below
Protective clothing You need to wear clothes that, at least, coveryour forearms (I wear a high collar sweater ? for all jobs, however small).
Just holding unfinished glass fiber projects (or carbon fiber for that matter)
will make your arms itch for days!! When sanding, sawing or filing you can?t
do without. I can tell you plenty of stories when I have ignored this and
regretted it for days...
2. Evaluating the part to copy
I?ll start off with stating the obvious. Make sure that the shape you are trying
to copy has a "natural release".[image: Image15.jpg] border='0' alt='user posted image' />
Pic 1.
Unfortunately it?s seldom this easy to see. However, as long as you choose
to copy an existing part chances are that it will be all right. Honda needed
it to come off their moulds too!
3. Preparation of the part to copy
If you already have broken the part you need, glue it back together with superglue
and sand it a bit. It may not work as fairing but will make the perfect "plug".
If you intend to use the part you are copying again, you need to be a little
careful! Polyester can be tough on decals. Cover those with some type of film,
you can fix the marks the film leaves later. I have never covered my decals
and never had a problem with it, but don?t say I didn?t warn you.
First, you need a nice shiny surface on the part you want
to copy. Not only so the copy will be nice, but so that the mould you are about
to make will let go. If the part is not shiny and smooth, rub away with some
polishing compound and finish it with 2 waxings. If you don?t do this thoroughly
you will be sorry later!
[image: Image1.jpg] border='0' alt='user posted image' />
Pic 2. Glue bits on and make the surface of the original shiny so the mould
lets go.
Second, apply release agent (see pic 9). I actually don?t know
what I use! I bought a can from a boat builder and I cannot remember what he
said it was. Probably polyvinyl alcohol, at least this is widely used
for this purpose. Some uses only wax, but I don?t quite trust it.
4. Making the mould
Gelcoat
"Paint" the original with two or three layers of Gelcoat. Let the
Gelcoat almost harden between the layers. If you don?t let it harden a bit before
the glass fiber application (below) the fibers may push thru and ruin the nice
surface the gelcoat is supposed to give. Not letting it harden fully will reduce
the risk of the layers separating. If you can?t be there until later, wash the
gelcoat with acetone, or something similarly that takes everything fatty away,
before you apply the next layer. A few % (5 or so) of paraffin in the Gelcoat
will give it an even glossier surface/makes it release from the plug easier,
but I don?t find this necessary.
[image: Image2.jpg] border='0' alt='user posted image' />
Pic 3. The original, "painted" with a few coats of Gelcoat
Polyester and glass fiber
A. Prepare the glass fiber
Precut the shapes you need in the quantity you need so you don?t have to do
that in the middle of the applying process ? it can get unbelievably messy!
Non-woven mats of glass fiber will follow most shapes (with the exception of
really sharp edges), but you will get excess of material in the wrong places
when you try to fold it in unnatural ways (see Pic 12). I rather use a few different
pieces that together builds the shape of the mould.
The Gelcoat gives a nice surface but is a little brittle and will crack if
you don?t support it with something. That?s why it?s now time for GRP (Glass
fiber Reinforced Plastic). The plastic in my case is polyester but you may as
well use epoxy. (See my comparisons between working with polyester and epoxi
at the end of this stunning and whitty write up)
[image: Image3.jpg] border='0' alt='user posted image' />
Pic 4. Precut enough glass fiber "sheets"! It may be hard to get
one piece of glass fiber mat to follow the entire shape. Make "sub parts"-
here?s the top of the seat cowl.
[image: Image4.jpg] border='0' alt='user posted image' />
Pic 5. And this one is the front. The solid line is the actual shape, the dotted
line is were I cut, giving some overlap.
B. Laminate!
The best thing now is if you have an hour or so on your hands so that you can
do this in one sequence. Three layers of fiber will do for the big surfaces
of most bike related projects. Reinforce with extra layers in areas that may
be strained.
Apply one thick layer of polyester onto the gelcoat and ... Place one of the precut pieces of glass fiber mat onto that. Usea brush or (preferrably) a paint roller to work the mat into the polyester.
The glass fiber should to look wet (not white) all over! Apply more polyester
if it doesn?t. You can be liberal with the polyester now, you are making a
mould, not a piece of fairing, so weight is not an issue. When one precut
shape is applied ...
Do its neighbor until you have covered the entire plug. When you have done that, go on with the next layer of glass fiber in thesame way. You do have time to admire your work, but do the next layer before
the first layer have fully hardened. In this way you don?t run the risk
of layers separating later (this is especially important when you make the
fairing part of course).
[image: Image5.jpg] border='0' alt='user posted image' />
Pic 6. A glass fiber mat will soften when polyester is applied. Non-woven mats
will easily follow round shapes (pretty much like a fancy hairdo in the rain).
Work "wet in wet" ? i.e. apply the next layer while the one before
has not yet hardened.
C. Trim
When the applying process is finished, let the resin harden for a while. But
before it has hardened fully, cut the excess glass fiber with a pair of scissors.
This will leave you with less sawing and sanding and you will love that! Now,
leave it until tomorrow to let it harden and then... file and sand the laminate
to the edges of the plug.
[image: Image6.jpg] border='0' alt='user posted image' />
Pic 7. Use regular scissors to trim most of the excess off while not quite
hardened. You can do it later but then you will need a saw... and this saw dust
itches like crazy!
All that remains now is to get the mould to let go of the original.
Twist and bend until you see it separate somewhere, then start working in that
area. I use my air compressor to blow air into the crack, this usually separates
them. It can be a bitch though...
[image: Image7.jpg] border='0' alt='user posted image' />
Pic 8. Phew! It worked! The original is gone, and mould is loose. Just need
some fine trimming. The brownish stuff in the mould is the releasing agent,
it tears or washes off.
If you find some imperfections you can wet sand the surface with a 1200 grit
paper.
But if you did everything right, the surface is great and all you have to do
now is to...
start over again!!
4. Using the mould to make a new fairing part
This process is basically the same as making the mould. There are some things
that can be considered though.
Do you want it light, strong or good looking? It?s easy to use
too much resin. The rule of thumb for max strength/weight ratio is equal weights
of fiber and resin. Use the paint roller to even out the resin and work it into
the fibers, this saves much weight. I don?t use a gelcoat surface on my light
fairings since gelcoat cracks to easily and weighs too much for this use. It
does give a very good surface for parts made to look good.
Reinforce areas that you think will be strained. Corners, edges
and holes for fastenings are typical such areas.
Make a quick and dirty first try. Things may turn out differently
than expected so don?t use too much energy on that first copy.
Things to do before you can start applying polyester and glass fiber
As with the original, you have to wax and cover the mould with a releasingagent.
If there are some parts with sharp edges (and there always are) make someplastic bag covered sponges (see pic 14). You will see how they work later
but make them now.
Precut glass fiber shapes.[image: Image8.jpg] border='0' alt='user posted image' />
Pic 9. Wax and then cover the mould with releasing agent
Apply polyester and glass fiber
First apply a coat of polyester onto the mould. Now, this is IMPORTANT: if
you want a nice smooth surface with no small pits in it, without using gelcoat,
let the first coat of polyester gel before applying a thin second coat and then
apply the first glass fiber layer onto that.
As you see on the following pictures I don?t use different precut glass fiber
shapes as I did with the mould. On this kind of simple shape you may go either
way but the precut is safest for best surface result. The excess glass fiber
will fold and I cut it so that it won?t form pleats and the excess can go on
top of each other more easily
[image: Image9.jpg] border='0' alt='user posted image' />
Pic 10. When applying glass fiber and it makes folds like this...
[image: Image10.jpg] border='0' alt='user posted image' />
Pic 11. ... I just cut it so it makes layers instead, without creases.
Add more polyester to the piece and work it in with a brush or a paint roller
(not upsetting the strands to much) until all the glass fiber is "wet".
Try not to add more polyester than you need to get the glass fiber all
wet, it is easier to add than to take away resin. Time for the next layer, work
wet in wet as with the mould. 3 to 4 layers will do for most parts, most of
my seat cowl is only 2 layers since it isn?t really doing anything but trying
to look good. Where I anticipate strain (mounting tabs) it is 4 or 5 layers.
As you see in the next pic, there are ways to make glass fiber follow even
sharp bends.
[image: Image11.jpg] border='0' alt='user posted image' />
Pic 12. Where it is hard to get the glass fiber to follow the shape of the
mold, this method of using something spongy in a plastc bag may work.
Trim the edges as you did when making the mould and when it has hardened fully
? next day or so if you use polyester ? bend your new fairing part from the
mould.
[image: Image12.jpg] border='0' alt='user posted image' />
Pic 13. With some persuation it came off. Looking good so far...
[image: Image13.jpg] border='0' alt='user posted image' />
Pic 14, ...But THIS is
the moment of truth ? ahhh carma!
Now all that remains is some fine edge sanding and then the hated paint job.
[image: Image14.jpg] border='0' alt='user posted image' />
Pic 18, It is easy to get carried away when it is little more than an hours
job to make a new one! (the strange patterns are didgital, not there in real
life)
Summary of the steps
Clean, wax and apply release agentPrecut fiberglassApply (gelcoat x2, let gel before...) polyester and glassfiber, repeat polyesterand glassfiber while wet
Reinforce vulnerable areas Trim with scissors before hardeningTrim with file/paper to the edge of the plug/mouldEnjoy!Things to know when you?re working with Polyester
The DIY "polyester" you buy in a can is not just polyester. Italso contains the solvent styrene and, if it?s blueish when not hardened,
some organic cobalt compound (accelerator) and sometimes some wax.
The styrene is a very good reason to wear a gas filtering mask.The wax is there so that the styrene will not evaporate too quickly (makingit dry before it hardens). Some wax will be on the surface after the hardening.
You need to take this away if you add an additional polyester layer after
the previous layer has hardened, otherwise there is a risk that these layers
will separate in the future.
Too much hardener in the polyester will "burn" the plastic leavingbrown weak spots.
Too little hardener slows down the hardening process (surprise!), sometimesso much that the styrene has time to evaporate and the polyester dries before
it has the time to harden.
Before it becomes solid it gels for a short while. This gel cannot be workedand it?s a good idea not to try to reshape it when you start seeing that.
To add the next layer is OK though.
Comparison between polyester and epoxi
I mostly use polyester when working with glass fiber. Still, many things speaks
in the advantage of epoxi.
The smell! Epoxi (most anyway) does not contain a solvent and smells less.It also is less toxic (allthough allergenic so keep dressed and wear a dust
mask!)
Epoxi is stronger.Epoxi gives a more scratch resistant surface (won?t help the paint you paintit with I guess).
Epoxi is resistant to many chemicals (including gasoline and water)Epoxi goes through a "chewing gum" state where it is possibleto shape. This is great for places were it is hard to get the laminate to
follow the mold or plug when the laminate is wet.
Epoxi is clear, so if you want to imbed a decal or see that cool lookingcarbon fiber, epoxi is your choice.
If you keep the jar of mixed epoxi in the freezer, the so called "potlife" will be in the order of weeks! (depending on the Epoxi used obviously,
there are several types with varying caracteristics) This way you can minimize
the number of batches you have to make.
However...
Epoxi is more expensive.The weight relationship between base and hardener is important. Small deviationsgives big decreases in quality. This is a pain when working with small batches.
The mixing of base and hardener is very important, polyester is more forgivingin this sence.
That?s all folks, and good luck!