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All star !!!
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Discussion Starter · #1 ·
Let's say you wanna make a part out of some fiberglass...but you don;t have a mold for it...so you basically have to make a plug, and then make a mold around that, to end up making the final part....to which I get all that.

Here is the question though:

If you wanted to build something like an engine/frame side cover....can you just cover the side are with some plastic..or anything else to protect what is underneath, and then just start laying up glass and resin, to build up the shape...actually large then what you want, to leave room for sanding down?

And second....if you do that, in making of the plug...is there any issue if you sand so far down that you have removed the outer layer of resin and are actually sanding down the fiberglass itself? That is actually the more important question to me.

Thanks for replies. :rock:
 

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Perpetual Project
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Here is the question though:

If you wanted to build something like an engine/frame side cover....can you just cover the side are with some plastic..or anything else to protect what is underneath, and then just start laying up glass and resin, to build up the shape...actually large then what you want, to leave room for sanding down?

And second....if you do that, in making of the plug...is there any issue if you sand so far down that you have removed the outer layer of resin and are actually sanding down the fiberglass itself? That is actually the more important question to me.

Thanks for replies. :rock:
Answer to first part, yes you can do that. I've made a foam mold, covered it in saran wrap, and glassed over that. It wasn't the prettiest, but to get a crude shape to begin to work with it will work. You could also look into releasing agents like waxes that might work, though I'm not sure how they would work with metal.

There are some issues with your second question. If you are working on your plug and sand down through your resin and into the fibers themselves you will end up with imperfections. Basically little pits where the weave shows through, or little rises where the fibers stick up. The simple answer to that is to sand it down a little extra there, then come back and brush on a final coat of just resin in that area (or over the whole part isn't a bad idea). That last coat is what you can sand down to a polish finish - which is the only way to get a good mold made. Any small imperfection in the plug will be transfered to your mold, which will be transfered to your finished piece.
 

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All star !!!
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Discussion Starter · #3 ·
There are some issues with your second question. If you are working on your plug and sand down through your resin and into the fibers themselves you will end up with imperfections. Basically little pits where the weave shows through, or little rises where the fibers stick up. The simple answer to that is to sand it down a little extra there, then come back and brush on a final coat of just resin in that area (or over the whole part isn't a bad idea). That last coat is what you can sand down to a polish finish - which is the only way to get a good mold made. Any small imperfection in the plug will be transfered to your mold, which will be transfered to your finished piece.
Ok, that is what I was looking for...just wondering what goin down to the glass would do in the mold making process. Good idea on how to go about correcting it with just adding some more resin there....I think that is the way I will go about it. :party-smiley:
 

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I had a couple spots on my tail fairing that I sanded down too far originally and the web of the fibers started to "rise" up through. Same happened on my nose fairing. I just finished correcting those flaws with a thin coat of resin last week and now they're flawless.

This week is primer, next week is paint, and the following week is a "For Sale" sign:D:bawling:
 

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I'm kinds trying a few ideas with a bikini fairing I wann make. I'm trying to make a base mold of the front of my bike and then clay my ideas on it. So far foam in a can didnt work (yes i covers the bike to protect it). Today I made a wire mesh mold and a posterboard mold. But I'm not sure how im gonna use them either. For some reason I didnt think of covering the front with plastic then glassing over it. Maybe I'll try that tomorrow. I know one big problem I got is the [email protected] guage cluster on the 1st gen SV's. I would love to replace it but dont got the $$$ for that yet. I did find out that the foam in a can stuff will not stick to plastic drop cloths, which might be useful at some point.
 

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hello, you can do as you say in the 1st part. Just cover the side with plastic wrap or tin foil [i think thats aluminium foil for covering food in the oven]. The way i do it is to cover the piece in foil and use the foil to pack out any parts that need it by crumpling it up and pushing it in, the foil can also be lightly beaten into shape too.
After that i cover it with masking tape and a good coat of spray grease [if i had release agent i would have used that but i never seem to get any in time for my projects]. After that i start to glass over it.

To your 2nd question i dont think you need to worry about the matting tissue/csm poking out as it should all have the resin heavily soaked into it so as to have no dry sections. Make sure the resin is well mixed/soaked into the chopped strand matting. However if you get dry spots [we all do] then do as the others say and soak some more resin in. Try not to have a thick layer of only resin on top of the finished part as the resin on its own is VERY brittle and will crack if flexed to much. I sand down the glass and put filler in any of the low spots i get. then i will sand with some 180grit dry and dust off. After that i spray in a 2k filler primer as it is strong when cured and sands nicely to give that pro gel coat look [ or just use gel coat if you have it].
 

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I made a cover for my subframe that my seat pan sits on.

Instead of using plastic I covered everything with painters tape then I covered that with metal duct tape, any hardware store will have those. Then I waxed the metal tape so the fiberglass resin wouldn't stick. I actually used EZPOXY because you can work with it longer before it sets up. The metal tape is easy to form and holds it's shape so you can push it into tight corners and it will stay there. The blue painters tape does a good job of protecting the part. You could take a shape off a painted part and not damage it doing it this way. The downside is if you want to use the tape side you won't have a smooth finish. Using resin to repair bare areas is a great idea. It would also fill any pinholes that bondo wouldn't get into. I usually buy all my cloth and resin from Wicks Aircraft www.wicksaircraft.com


 

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check out how he figured the lines of his bike, nice idea.



how did he get the shapes biuld on to the base pieces though?
 

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I'm not really a glass king [thanks for the comment though :)]but i use it a lot. I dont find it that easy and it is time comsuming. The seat cowl to me 7 long nights [after making the base] to get the basic shape and get it in filler primer.
The body work lines and angles were done using a tip from the old skool suzuki site.
Didn't understand the last question about base pieces but will try to answer any questions on the build.
 

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did you use fiberglass on the cowl and undertray ? and how is it so thin looking did you use mat or straight resin ?
 

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yes they are made from fibreglass but i have used ABS plastic in the construction as well.
The undertray is a thin sheet of ABS cut to the shape needed with the glass added towards the end where it sits under the front seat. The sides were built up using f/glass paste. The ridges on the under tray are thin strips of ABS glued into postion and then layered with f/glass tissue and sanded to shape. It was done with the subframe and tail section on the bench upside down. It took a couple of weeks of nights to complete this [a night is about 6 hours or until i get too tierd].

The cowl is all fibreglass with the exception of the 2 fins which are ABS bonded with glass paste into position. They were pre shaped, glued and then finishedwith a thin skin of glass paste and filler. The little raised part between the fins was again ABS cut to the shape and glued and dressed with filler. The center part of the cowl[no clue what to call that bit] was shaped from kids coloured modelling clay. I rolled it out flat with a bottle to 10mm and cut a triangular shape out of it, then cut progressively smaller triangles out and stuck them on top of each other. I then used my fingers to press the indents into the clay. I then stuck a strip of ABS in the center to make the line down the middle. This gave me a good base to work with. Next it was spray glued and covered with clear food wrap and covered with glass matt&resin. This made a mould for me to make a f/glass copy of the clay part. Once the part was made out of glass i bonded it to the cowl and finished it off with filler. Now all that was left was to spray with filler primer and paint.
Fibreglass will have no problems with bonding to ABS plastic provided it is heavily keyed [40/60 grit paper] and wipe over with some cellulose thinner. Never has a panel split under normal use.
 

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awesome, thanks for the info. im definately gonna try this. hope my daughter doesnt cry when i go stealin her play-do.
 
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