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Engineery types: Epoxy?
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I am in the process of molishing my pillion seat to take a Givi top box.
Having removed the foam, the plastic 'frame' is actually dished. For
a variety of plastic related reasons, I need to raise the mounting plate
about 15-20mm above the level of the frame (to allow the rear of the box
to clear the rear plastic of the bike).
I can used some mdf or similar for that bit, but the bolts from the
mounting plate actually have to go through a section of the dished part
of the frame, so there is some 10mm between the plate and the frame.
Not ideal I think although it does seem pretty strong.
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Fill it with expanding builder's foam, shape it so the top is flat and
then a skim of fibreglass over the top to hold everything together and
make it paintable.
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I had considered the foam, but the fibreglass had escaped me. I like
that idea, been a long time since I did any 'laying up'...
Nice one.
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Looking over the other replies, I'd bolt some pre-drilled bobbins in
place before filling with the foam to give something solid for the box
to bolt through that won't deform.
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Then you can scoop the mess out with a trowel. Fibregalss resin will eat the
foam for fun. You need Polyester resin.
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Epoxy easts polyurethane?
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"Fibreglass resin" is polyester resin. Epoxy is more expensive and
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No it's not. Fibreglass resin is, believe it or not, for bonding fibreglass
cloth/matting/panles etc which is nothing at all to do with polyester. It's
"possible" to use fibreglass resin to bond polyester and it's "possible" to
use polyester resin to bond fibreglass, but they're different and fibreglass
resin eats various foams, including polyurethane foam. Polyester resin
doesn't eat foam.
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I never use polyester resin as I have enough epoxy to last a lifetime.
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Aye, Ok then , have it your way.
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Epoxy is more expensive and
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normally used with carbon fibre or kevlar, and for small repairs as
it sticks to epoxy or polyester. I didn't know that either dissolved
any sort of foam.
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Fibreglass resin does. Ask any aeromodeller who's built foam cored wings and
joined the two halves with fibreglass resin.
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No, fibreglass resin eats expandy foam. Polyurethane resin doesn't.
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Gotcha. I think it's gonna be irrelevant now.
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To make it a better mount, it seems that I could fill the 'dish' with
something like epoxy to create a flat, solid base for the plate and
'spacers'
Thing is I need about a litre of the stuff. From B+Q that is gonna cost
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It's also going to get pretty hot whilst it's curing, if you try to do
it all in one go.
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That had occurred as well. Layers would probably be a better idea.
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I'm not sure I have any better suggestions, TBH. If you do decide to go
this route, have a chat with your local friendly model shop, they stock
pouring epoxy in reasonable quantities.
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Yep, that was one of my thoughts.
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So suggestions for suppliers, or alternatives? Maybe Isopon or similar
would do as well?
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Epoxy seems to be £20 or so per litre. Plenty of chandlers have it
You need some filler and glass mat to reduce weight and increase
strength, or think of a different solution.
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How about foam filler with a layer of epoxy over the top?
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That'd work perfectly and the foam will hold any bobbins you care to use
too.
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Confused now. Didn't you say up there that the epoxy would eat the foam?
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Crossed wires or summat, but no, epoxy resin won't eat the foam, but
fibreglass resin will.
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