Who here has worked with fiberglass a little?

[peteGS]

I haven't done anything structural so I'll leave that to the others, but on the top I wouldn't be sanding the glass down unless there are some really high/low spots, I'd be adding body filler first then sanding it down.

If you still need to take the big bubbles out then that's a different story of course...

Just my 2 cents on the topic anyway, I will have to defer to the other more experienced guys!!

[Big Rich]

Good point Pete - I get what you're saying. The bubbles are about 25mm around and are the top layer separating from the lower layer.....I think if I did NOT sand them down, they would end up flexing (like they do now) and cracking the top / finished surface apart. Make sense?

And one thing I forgot to mention - where my butt is actually planted on the seating area, there is a sheet of 1/8" plastic. That plastic has been heated up and bent to conform to the frame rails. So the fiberglass won't be supporting my weight by itself.

[peteGS]

Got ya' Rich, yeah those bubbles need to go, especially if they're creating an air gap in between the layers! That will let you down for sure.

That sounds like the optimal place to some of that paste filling after they're gone for sure.

Good idea putting that extra support under there too, I've always wondered how strong a pure fibreglass seat pan would be and how many layers you'd need to use to ensure it doesn't crack.

[J_Walker]

2 layers of 6 oz fiberglass is strong enough to glass a wooden hauled boat to be dragged across rocks and sand. for a seat pan I'd say about 5 mill thickness should be plenty strong.

Gelcoat.
fiberglass cloth [or roving]
fiber glass fibers laid Horizontal.
Then laid Vertical.
Horizontal
Vertical
...
Then a final cloth [roving] mat on top


also lets say the part hangs over the edge of something, like you cut a sub frame and want your new part to hang off a bit. 1/8" thick 1/2" square stock inbedded into the fiberglass will give you lots of strength. and will keep it from bending on you.

PS: the websites prices aren't that crazy. but just a little tip, if your epoxy or fiberglass resin doesn't "stick" to your cloth at a 90 degree angle to you. and it sloops down kinda like getting paint runs then its either really bad resin, or its old/out dated and you should pack it back up and take it back to where you got it and request a full refund. not only does this effect your  ability to lay up fiberglass but also the strength of your part. once cured, will it fall apart and turn to little fiberglass splinters? Probably not. but it won't be nearly as strong as it could be.

[Joolstacho]

'Kay so I've made a few seat bases. Most recent was one for a CX500, and it was absolutely strong enough at about 2.5mm - 3mm thick. 5mm is way too thick and unnecessarily heavy.
(Obviously it depends to an extent on the support afforded by the subframe, but my CX one had loads of strength and rigidity to spare).
As I said before, if you're not moulding a 'part' from a female mould, a gelcoat is a complete waste of time.

[Big Rich]

Thanks fellas! Good info all around.

I'm finishing up for work this morning, so I should make some more progress (or more questions on how to fix my mistakes) over the next couple days.

[peteGS]

That's great info to know guys, I fully intend to do more fibreglass work on future projects so it's good to get that sort of info early on before they're even planned...

I was able to use my stock seat pan on my 450 with keeping it dual seat and keeping the stock tail piece subframe but I have other ideas moving forwards and a fibreglass pan would make some of those ideas a lot easier to make reality...

Now back to Rich's thread 

[J_Walker]

'Kay so I've made a few seat bases. Most recent was one for a CX500, and it was absolutely strong enough at about 2.5mm - 3mm thick. 5mm is way too thick and unnecessarily heavy.
(Obviously it depends to an extent on the support afforded by the subframe, but my CX one had loads of strength and rigidity to spare).
As I said before, if you're not moulding a 'part' from a female mould, a gelcoat is a complete waste of time.

yeah 3 mill. I know how that goes. your "friend" borrows your bike and weighs 240 pounds and "crack" that's what 3 mill does.

But its cool. clearly I know nothing about what I'm talking about.

[Joolstacho]

Err, read my second line, I think you missed it.
Clearly you THINK you do!

[Janx101]

Ummm yeah, any thickness of fibreglass without a subframe  supporting the setup would probably go snap over time...

Fibreglass is good stuff bit its not magic!

Was the original idea to just glass a seat up and have no frame under it?

[Big Rich]

Who was that question for Janx? Obviously Jools' CX seat had a solid frame under it, and my seat will have a solid frame under it as well. I agree that fiberglass is awesome stuff, but it's not the red pill OR the blue pill people are looking for.

Let's remember fellas: nobody is bashing anybody here. Just handing out advice when it is asked for. And NONE of it is disregarded!   

Updates on my seat later....

[Janx101]

Ahh that was a question at large? ... I couldn't remember who started what....

I plead tired again!

[Joolstacho]

Yep boys, we're all just doing our best eh?

[Big Rich]

Ok, time to bump this fiberglass thread.

I'm getting ready to try to smooth out the surface and want the most solid surface possible. Something tells me normal Bondo isn't going to give me the best results possible.... so what am I looking at next? Fiberglass mat chopped up and mixed with resin? Or is there another body filler that I can research a little?

Thanks in advance folks.

[peteGS]

If there's largish holes or indents that need some serious filling, do the paste I mentioned earlier with the chopped up mat and resin.

If it's just levelling the surface, then fibreglass reinforced body filler is your best bet.

Once you've got that nice and flat after doing those, you can use some blade putty for any little spots that may need that extra touch. The one I used is a one part you use straight out of the tin and is very easy to work with to get that really smooth finish.

Best bet for a real smooth finish is to blade putty the entire surface then sand it back, that will give you just that little extra buffer over the matting and body filler to get rid of those annoying imperfections that insist on showing up.

[Big Rich]

Thanks Pete! That's the info I was looking for.

 

[peteGS]

No probs Rich, you'll do just fine I'm sure!


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