Fiberglass How To's

[gangstajpimpin 10+ year member]

http://www.uscomposites.com

bout 35/gal

 

[bad03ranger 10+ year member]

Can i glass my MDF enclosure?

Do i wrap the enclosure in fleece then glass or can i just spread body filler over it and smooth it down and paint it

 

[j1b1e1 10+ year member]

Old threads crash and burn. Only one link still works on the first page. Anyone got any good site for fiberglass. I'm trying to shed some weight and gain some box volume for my two 13w7's in my trunk... Thanks!

 

[BassMechkanic 10+ year member]

post 106

 

[FLYONWALL9@AOL. 10+ year member]

Old threads crash and burn. Only one link still works on the first page. Anyone got any good site for fiberglass. I'm trying to shed some weight and gain some box volume for my two 13w7's in my trunk... Thanks!

Though I have only built only about 30 or so parts for cars out of fiberglass I can speak from an educated boat builders perspective. I have read through most of this thread and I gotta say, most of the techniques will work I wouldn't call them proper fiberglass techniques from my perspective. If you really want to know how to properly lay up fiberglass you should read

http://www.bateau2.com/howto/epoxy_basics.php

you say you want to shed some weight? Well, I am going to go against the grain in saying this but here goes...... and this is how I build all my fiberglass parts and I will build my next enclosure using this method. Because I have a light weight sports car, adding a 100lb subwoofer enclosure is out of the question! I'll kind of do a step by step which will use no fasteners.

In weight savings you don't need to use 1/2 or thicker MDF, you simply need to build a "composite" enclosure. You will want to use 1/4" high grade ply. What your looking for is as few voids as possible. You know those football biscuits you see in plywood, well that was once a void in the lamination. High grade plywood will have 5 or more layers, this link is for example purpose only: http://plywood.boatbuildercentral.com/

Your likely going to make the baffle out of fiberglass with only wooden rings, the sides and bottom will likely be made of ply. So, make all your cuts, lay out the box as if you were about to put screws in it; only drill 1/8" holes about every 4 to 6" apart and about 1/2" from the boards edge. You will then simply use zip ties, cable ties, copper wire, or fishing wire to "stitch" the box together LOOSELY. GAPS ARE GOOD!!! I would look for a gap no less than 1/8" what you can do is use your drill bit as a spacer, or popsicle sticks work great. Once you have the box stitched up your going to mix a paste of epoxy and a filler to the consistency of peanut butter. You want it to be ferm so that it will hold its shape. Using a ziplock bag, cut the corner and squeeze out the mixture between each cable tie. Then shape to make an inside radius. You can make a custom tool out of paint sticks, or use a tongue depressor. Once your "fillet" dries enough so it still can be shaped you can then pull out the ties and fill all the gaps around the inside. Your looking for about a 1/2" radius. You can put tape each side of the joint before putting in your epoxy and filler so that clean up will be much easier. Once its dry just pull up the tape.

Structural fillets should be made of wood flour or milled glass fiber. I like wood flour its as strong as nails, VERY hard to sand, holds its shape well.

http://boatbuildercentral.com/proddetail.php?prod=E_woo_1lb

Now that your fillets have dried you can then use fiberglass tape. I like 6" biaxial 6oz or heavier. I use an over lap lay-up, that is; 4" of the tape will be on one side 2 on the other side of the joint. Your next layer will then be 4" over the top of the first 2" and 2" over the 4." YOU DO NOT, have to wait for your fillet to dry completely. You can work "wet on wet" once the fillet is tacky your ready to lay tape. Wet your fiberglass out.

NOW here is where I'm going to get flamed. YOU DO NOT have to saturate the cloth. Pour little pools of resin onto your fiberglass tape. Using a squeegee PUSH the resin into the cloth. This will push out any bubbles and bed the fiberglass into the plywood. What your looking for is a wet gauze look. The fiberglass weave will not be filled at this point! This joint will have a peal strength 100 times stronger than the fiberglass work your used to seeing.

Still working wet on wet and on the inside of the box your going to lay one layer of wide fabric. It will be the width of the panel from your fillet to the boxes edge. You can use one continuous piece, starting at one corner and going all the way around the box back to your starting corner. Let me back up a second. You can go ahead and glass the back of the box then do the sides. Again I like 6oz or better biaxial fiber glass http://boatbuildercentral.com/proddetail.php?prod=E_bias_1708

Using the same method as with the tape. Pour little pools of resin onto the panel your working with and push the resin into the fiberglass. Again, your looking for something that looks like wet gauze, and your weave WILL NOT be filled with this lay up. Once this process has fully dried and within 24 hours your going to mix a slurry of resin and a filler. Your wanting to build a light weight box so use "MICRO BALLOONS" http://boatbuildercentral.com/proddetail.php?prod=E_mic_.25lb

The consistency your looking for is ketchup or mayonnaise. Pour that into pools and push it into the weave but only this time your filling the weave. You will only be able to work on one panel at a time until its dry enough that it does not run or sag.

By this time you will have the inside of the box completely laid up. You can now move to the outside of the box and use the same lay-up schedule as the inside. You can also at this time mold your baffle into or onto the boxes face. Also, this type of enclosure should use dividers or interior supports.

Now I assure you that building an enclosure as described above will not only be less weight but MUCH stronger than using 1/2 or greater MDF. I believe in it so much so that I would be willing to pay a bounty if proven other wise. IF the fiberglass lay-up is per the above directions.

I've seen on every car audio board the improper use of resins. Even if you don't build a box as per the above directions; if you just use the method for wetting out your materials you will not only use FAR less resin but the end results will be a much stronger product.

DISCLAIMER: I take various medications, due to which if any misspellings and punctuation's are found get over it..... lol... I do hope this helps someone, if nothing more than to save people money on using the proper amounts of materials. Lets stop these over saturated fiberglass lay-ups. Again, the links provided are for materials description only and not meant to be an ad. I have however, purchased many thousands of dollars worth of fiberglass and resins from them. They are fine people.

 

[godhatescivics 10+ year member]

 

[j1b1e1 10+ year member]

Wow, lots of info... I'll read it in the morning. Thanks!!!!!!!!!!!!!!!

 

[GI JOEY 10+ year member]

how would you secure a 3/4 mdf box to a fiberglass bottom? Not sure how to attach the fiberglass.

 

[nineball 10+ year member]

more fiberglass

 

[FLYONWALL9@AOL. 10+ year member]

your going to need to make both surfaces mate together

as closely as possible. If they don't touch then your going

to need a glue or bed of resin to sink it into. To make said

glue...

I'm guessing we are talking about polyester resin? Your

going to need a thickening agent like, milled fiberglass fiber,

micro balloons, or a very strong glue made of epoxy and

wood flour. The factor which determines is what is the dis-

tance between the bottom of the board and fiberglass? This

will determine how thick and what the glue will be made of...

If the surfaces mate together with very little gap then I would

use milled fiberglass fibers mixed with resin. Make a nice bed of

the mixture and set the MDF into it. Then you can glass over it.

If you would like, you can PM me or mail @ flyonwall9@aol.com

I can supply you with links with a step by step. If I can find them

through WEST SYSTEM web site.

I hope I was able to help

 

[BassMechkanic 10+ year member]

you can also use saw dust, mix that into your resin, makes it thicker like a paste, after that sets then put a couple layers of matt and resin

 

[nineball 10+ year member]

you can also use saw dust, mix that into your resin, makes it thicker like a paste, after that sets then put a couple layers of matt and resin

i would use duraglass before that

 

[GI JOEY 10+ year member]

How many layers do you think I should do? I am only doing the bottom of the enclosure in fiberglass, I have read 7 and I have read it depends on the size of the box and the subs your running. Since it is the bottom it will have addtional support from the floor of the truck. I have also seen that you get higher spl numbers from a box that flexes a little.

 

[nineball 10+ year member]

you have seen wrong. flex is your enemy. you need enough fg so that you have NO flex. if you can stand on the fg section and it flexes you need more.

 

[GI JOEY 10+ year member]

Well the box is solid as hell. It is about 55 inches wide and I can barely get it to budge by lifting one side and pushing down on the middle. This is about 7 layers and 2.5 gallons of resin. With the rest of the box/ mdf it should make the bottom even more rigid. I used the bottom and top layers with fiberglass cloth and the middle layers are fiberglas matt. Its about 1/3 inch thick as of now.

Think this is enough?