1979 CB750 DOHC Monoshock Build

Hey Bananas, I'm only working on my first fiberglass project, too, but I experienced the same thing on the inside of my tail piece after I took the foam out of it. I, too, think I used too little hardener.

I added another layer of fiberglass and it seemed to cure it.

Keep up the great work!

-Sherm
 
Thanks. I discovered that putting release fabric on top of the last coat of fiberglass makes a huge difference in the surface finish of the part I'm making. Here's where I ordered mine.

bananas said:
Whoa! I don't know how your glasswork is so clean... makes it looks like mine was produced by a monkey. That's another great way of making a front fender. The technique I plan to use is awesome for us without something to glass over (other than a new tire). In my case I acquired the GSXR front-end piecemeal and normally I'm a big fan of modern sportbike fenders but never got the SRAD fender as its kind of... awfully 90's looking.

Checked out your build the XS looks great!
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are you guys using polyester resin ? if so you don't add acetone and you really should be using laminating resin you cant make good part laminating with finish resin if you are letting it cure between layers, the wax prevents a good bond betweeen layers
 
Acetone? Did you mix acetone in with the resin? I've heard it used with epoxy resin to thin a bit but don't think its good with polyester. I could be wrong though, some more experienced composite guys here would know. I use it to clean up after I'm finished since it dissolves resin so good.

They could still be tacky because you used unwaxed resin (i.e. laminating) instead of waxed resin. Laminating resin will stay tacky so you can lay the next layers on and have a good chemical adhesion. It needs to be sealed off from air for it to lose the tackiness. However, it still sets hard, just that the top is a bit tacky, sounds like yours is not even curing fully.
 
agreed but laminating resin is the key to easy/strong trouble free part making finishing resin is just that,for finishing for the final layer or a quick one shot job/repair where all layers are done in one wet run
 
Hey Bananas-

The thing that helped me the most on my fiberglass project was using spray adhesive to hold the next layer of fabric in place before I started painting in the resin.

I read that on another forum long ago.

-Sherm
 
Bigsherm said:
Hey Bananas-

The thing that helped me the most on my fiberglass project was using spray adhesive to hold the next layer of fabric in place before I started painting in the resin.

I read that on another forum long ago.

-Sherm
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no no no no,what you made was a shit for strength part, that is why you use laminating resin because it stays tacky and allows the next layer to be layed down dry and clean ,then filled
 
BSA, I've only been back on these boards for a few days, but I already learned you can always be counted on for maximum abrasiveness.

-Sherm
 
bananas said:
I'm using "Bondo Fibreglass Resin". I've been assuming its an epoxy resin. This stuff.
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nope that is finishing or one step resin (polyester)you need laminating resin(polyester) because it is sooo much easier to work with
 
bananas said:
I'm using "Bondo Fibreglass Resin". I've been assuming its an epoxy resin. This stuff.
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That's polyester. Next time don't thin with acetone, just use the resin and hardener in the correct amounts, should work fine. If it doesn't the resin may be dead since it has a shelf life and it could be old stuff.
 
xb33bsa said:
nope that is finishing or one step resin (polyester)you need laminating resin(polyester) because it is sooo much easier to work with
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Oh shit. So I'm guessing its the acetone I used? TBH when I bought it i grabbed the mat/cloth and this can of resin was next to it so I figured they were all the same hahaha... It was definitely shit to work with. So I'm guessing I gotta start over?
 
HerrDeacon said:
That's polyester. Next time don't thin with acetone, just use the resin and hardener in the correct amounts, should work fine. If it doesn't the resin may be dead since it has a shelf life and it could be old stuff.
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but you wont get a bond between layers that have cured, the wax prevents it, so the work must be done all at once fully wet and is like blind finger painting
 
bananas said:
Oh shit. So I'm guessing its the acetone I used? TBH when I bought it i grabbed the mat/cloth and this can of resin was next to it so I figured they were all the same hahaha... It was definitely shit to work with. So I'm guessing I gotta start over?
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get some laminating resin and you can do layer after layer each layer is done after the cloth has been filled (minimaly) and after the resin has "kicked off"
step one: after waxing the form you paint it with lam resin,let it kick off till it is like flypaper sticky....
step 2: then with clean dry hands you lay down the cloth let it kick off a bit more then fill the cloth, let it kick off till sticky again and repeat
this allows you to lay each ;layer down dry and the glass sticks in place even in inside corners
final layer with the finishing resin
 
xb33bsa said:
but you wont get a bond between layers that have cured, the wax prevents it, so the work must be done all at once fully wet and is like blind finger painting
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XB, you really need to learn to read and stop being so damn belligerent. I know the difference between the two types of resin and when they are used. I never said to use a waxed resin, but merely answering banana's question about what type of resin the Bondo was and a possible reason on why it never cured.

Also, I'm starting to hate Tapatalk since it doesn't block people on my ignore list.
 
Damnit. Thanks for the info guys!

Guess I'll see if they harden up over the next day or so and if not they'll get redone.
 
One thing I did when making my seat pan and electrical tray was on top of the masking tape I used aluminum tape(for duct work, not duct tape tho) and waxed it and my parts came off easy. I was worried about the resin soaking into the masking tape and being a pain to get off. And I had saw someone else do that. And I'm sure the acetone is your problem I used same resin and parts came out fine and fully cured in less than a day, were hard enough to remove in hour or so, maybe less I didn't try earlier. Just my 2 cents worth, I am by no means a fiberglass expert but I did get useable parts with minimal effort.
 
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