fiberglass inside, instead of outside?

I was thinking yesterday as I was driving home about glassing. Then I thought about how much easier a project would be if you could glass it from the inside instead of the outside. Then you could just put your bondo on the fleece and as long as you stretch it nice and tight like you should. It would take just a little sanding and you'd be smooth as glass, not fiberglass. hehe. Instead of having to sand down the glass and then bondo and all that.

Does anyone do this? How from the speaker hole and just reach in or do you cut a hole and then patch it later?

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Learning the trade one fiberglass creation at a time!

Are you serious?!

I agree that it would be simpler to bondo fleece but this would only work if the enclosure is in two pieces. Once you've glassed the inside of the "Cover" you'd attach it to the enclosure. But how would you do that?

If the fleece is attached to the enclosure already, how would you reach in though an 11.5 inch hole with both hands and see what you're doing? How would you make sure all the bubbles are squeezed out and that you have a sound structure?

I could have made a play on words with your username name but prefer to refrain.  Prove us wrong and build a box with many pix.

I could be wrong.

I once asked who the hel* would want to see a bunch of guys losing traction on purpose when even a monkey knows how to push a gas pedal to the floor until HP overtakes rubber adhesion. It ain't talent - it's contrary to what they teach at drag racing school. Yet - drifting became a phenomenon. DOH! 

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Prepare your future. It wasn't the lack of stones that killed the stone age.

I've glassed projects many times from the inside. Its not as hard as you think as long as you plan ahead. When I'm designing and building my frame work I try to include a removable section of mdf. Usually on the bottom or back of the project. After the glass is laid I re-attach the mdf panel and seal it up.
It does take a little longer to design the project this way. But it saves a ton of time in the sanding process.
Now this doesnt work for all projects. Sometimes something is just too small or ackwardly shaped to make this approach possible. But as long as there's a big enough section of mdf that allows you to really get in there and do a good job, its worth it.

I dont have any build up pics, but I glassed all these from the inside:



on this one I removed the bottom.



on this one I removed the back



removed the bottom as well


You get the idea. Next time I glass from the inside I'll make sure i take some build-up pics.

Nice work! Real smooth!   

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Prepare your future. It wasn't the lack of stones that killed the stone age.

So anarchy do you cut a section out of the mdf? I think im lost on that part. I was thinking of cutting a section out, on the projects that have the glass touching all the mdf. Then reattaching what you cut out once you get done. With liquid nails, then laying some glass across the top through the speaker hole.   

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Learning the trade one fiberglass creation at a time!

No I dont cut a section out. I build the frame work a certain way to allow a large piece of the mdf to be taken off but still have the rest of the frame maintain its shape. Give me a sec and I'll try to draw up an example.

ok, lets say you build a basic rectangular frame. The opening in the front is where you mount your rings:





Dont glue the grey panel(1)in place yet. Just hold it in with screws till you get the shape of the framework you want. After your fleece is streched and resined you can remove the back panel(1). Now you have a large opening where you can lay down your glass from the inside. Once your done glassing put glue around the edges of the back panel and secure it back into place with nails/screws/etc.
Now this is a very very basic example. Sometimes you have to get a little more creative to make a frame with removable peices that can still maintain its shape without moving.

very nice work anarchy.

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Shaking The Neighborhood

Thanks for the compliments guys.

very nice anarchy...

sometimes you are not able to remove a whole panel like that though because there is only the sides back and bottom made of MDF...

in that case i make a double back panel...i cut the whole centre out of the panel, regardless of the shape of the panel cut the entire centre out of it leaving about 1.5 inches all the way around...(similar to a flush mounted speaker ring)

then you can glue and screw the panel with the huge friggin hole in it to the rest of the box (sides and bottom) stretch your fabric and resina away...

through the acess you have now built you can lay you mat to the inside of the box...once done with the layup...simply glue and screw your other full panel over the back and your good to go...

using a method like this requires a little more math for clearance tolerances, and for volume measurements aswell...weight of the access ring panel is not and issue since you are not putting in a top panel of MDF..rather building the thop and the front from fiberglass and saving the weight there...

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Fiberglass Guru.

If you frame up properly and rollout all air bubbles on the fiberglass you should be able to come out with a project in the same smoothness without extra work. It's all about technique and how you use your materials to build.

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Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA

Awesome idea guys. Thanks anarchy really cool.     Cougar still a little confused on your idea, but let me see if I got it. Basically you cut a hole then you take a piece of mdf and cover that hole after your done glassing with a piece that is to cover say the whole back piece, if thats the area you cut out? 

jeff i've tried and tried. I just cant get it to come out smoothly. I think i end up putting more glass in some areas then others and stuff like that. I usually dont have any bubbles now, or at least not many. Nothing thats a big problem. I always end up with tons of bumps in the glass though.

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Learning the trade one fiberglass creation at a time!

Hey guys something that will make life easier too is this

you do exactly what anarchy said but do this too

make your frame and structure stretch your fleece and fasten it like normal now soak the fleece with your normal resin mix once you have soaked it to the point where you would normally call it done mix one more batch of resin this time mix it 50/50 with bondo add cream hardner and the liquid hardner. Now brush this mix over the wet fleece (do not wait for the orignal resin to dry) let the fleece now dry lay your chop mat on the inside to desired thickness. Now you sand the fleece Guess what it will sand like bondo and will require little or no extra bondo to make perfect.

hope this helps

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Fred Sherri

Future ive read about this over and over but ive never actually tried it.  I've so many goods and bads about it.  I guess this method is supposed to be like self leveling though???  

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Learning the trade one fiberglass creation at a time!

ya you got it  reality ,it levels the surface so ther isnt so much bondo work to do and cuts down prep time huge.

The only Con to this that i can see is if someone were to use this mix to soak the fleece right through. You have to make sure you have the fleece 100% soaked through with just resin and hardner before applying the 50/50 mix. While applying the 50/50 mix just use enough to cover the whole surface you dont want it to soak completely through the fleece or it will be weaker than the rest. I mix mine about 70% bondo 30% resin this way it stays pretty think and will stay on the surface the best part is it will sand like bondo not rock hard resin.

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Fred Sherri

This would work well with square or rectangular boxes. I've done it before with great success. If your using a slot port try and plan enough space around it to get your hand in to glass. But what if your building a spare tire well enclosure? How would you do this? would you build a frame around your tire well fiberglass mold then make a seperate top? Then glass the top fom the inside after you've stretched the fleece and glassed it? THANKS FOR YOUR REPLYS!!!!!

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My thoughts and I havent completely thought this through, but people make the spare tire well enclosures in two pieces all the time. So I would think you just make the bottom, then make a frame for the top. Fiberglass the inside of the top and then attach the two with fiberglass. Ive seen people make the two separately but ive never seen how. I would it would be hard to attach a square frame to the shape of a spare tire well. Im pretty sure ive seen it though, just dont remember how they did it.

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Learning the trade one fiberglass creation at a time!

I make spare tire enclosures in two peices when doing a molded top but when you do a molded top most of the time you will be making a trim panel for cosmetics so it really does not matter if you lay the glass on the out side of the structure.

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Fred Sherri