im having to make myown box for my 04 silverado ext cab for subs under the back bench seat. The problems with using MDF is its hard to get a lot of air space because there are so many curves, and nooks, and cranies, that if you dont make the box so that it uses each one of them your not gona get the air space you need. Im just barley able to make .8cu ft., and that box i made was too big so i have to start over.
If i used fiberglass to make at least the bottom it would save me a lot of effort and i would be able to easily get the required airspace. But i had a firend tell me that if i use fiberglass it wouldent sound so good because of the acoustic qualities of fiberglass.
what should i do? is my friend right? could i get away with makind it fiberglass and then just like put MDF pices in it?
any advice is much apreciated. thx
If i used fiberglass to make at least the bottom it would save me a lot of effort and i would be able to easily get the required airspace. But i had a firend tell me that if i use fiberglass it wouldent sound so good because of the acoustic qualities of fiberglass.
what should i do? is my friend right? could i get away with makind it fiberglass and then just like put MDF pices in it?
any advice is much apreciated. thx
I'm not sure about the acoustic quality of fiberglass.. but since this glass shell is actually sitting/molded on your car's chassis, which I presume is steel, you'd also get the benefits of a rigid surface. Besides a lot of SQ setup incorporate fiberglass in their auto installation.
hoped that helped
hoped that helped
fiberglass has been used exensively in car audio. here are the key points:
1.) use a laminating resin. general purpose and finishing resins often have short working times and a wax compond included. the wax dries nice and glossy, but new fiberglass layers will not bond to it. an iso resin is ideal becuase it has more tolerance to heat.
2.) fiberglass will not bond to duct tape or aluminum foil.
3.) fiberglass is an irritant. if you get it on you, well, unhappy until you can get to some:
4.) acetone will help get resin from your hand.
5.) curves are important. move curves means more strength. the flat points of a fiberglass structure will be the weakest.
6.) keep sharp angles to a minimum. fiberglass will not take kindly to going around 90 degress edges.
7.) use 2 pair of latex gloves. this stuff will eat through 1 layer without much problem.
8.) try for 4-6 layers of mat. cloth is expensive and you never seem to get done because it adds little mass. 4-6 layers should be as sturdy as MDF that is 2-3 times as thick.
9.) strength depends on the geometry, number of layers, amount of air-pockets (bad), the ratio of resin to glass, and the number of free ester chains in the resin. vinyl ester has more and is stronger then polyester, but with 4-6 layers it should not matter.
10.) VERY IMPORTANT -- all surfaces in the car must be covered. covered with plastic or with foil or with duct tape. this stuff will not ever come out of your carpeting
the typical fiberglass install is 2 parts -- part 1 is making the boundary mould. this is where the fiberglass molds into the vehicles contours. use a few layers are you will not be able to add layers later without losing form.
part 2 involves the speaker mounts (speaker rings) and amprack mounts. you can build a wooden tray for an amplifier is desired. make sure to have room to run wires or run wires through pipes... for woofers, a wooden support frame is usually made for large projects. for smaller projects stiff metal mesh is used along with picture frame tape (metal strip with holes) to make a form for the inside. some users will opt to make this structure from MDF instead of fiberglass. for kick-panels a polyurethane foam is applied and carved to get a desired form. from there a layer of fleech is uses. t-shirts can be used. basically it is a layer that can add support for the extra 4-6 layers without folding.
1.) use a laminating resin. general purpose and finishing resins often have short working times and a wax compond included. the wax dries nice and glossy, but new fiberglass layers will not bond to it. an iso resin is ideal becuase it has more tolerance to heat.
2.) fiberglass will not bond to duct tape or aluminum foil.
3.) fiberglass is an irritant. if you get it on you, well, unhappy until you can get to some:
4.) acetone will help get resin from your hand.
5.) curves are important. move curves means more strength. the flat points of a fiberglass structure will be the weakest.
6.) keep sharp angles to a minimum. fiberglass will not take kindly to going around 90 degress edges.
7.) use 2 pair of latex gloves. this stuff will eat through 1 layer without much problem.
8.) try for 4-6 layers of mat. cloth is expensive and you never seem to get done because it adds little mass. 4-6 layers should be as sturdy as MDF that is 2-3 times as thick.
9.) strength depends on the geometry, number of layers, amount of air-pockets (bad), the ratio of resin to glass, and the number of free ester chains in the resin. vinyl ester has more and is stronger then polyester, but with 4-6 layers it should not matter.
10.) VERY IMPORTANT -- all surfaces in the car must be covered. covered with plastic or with foil or with duct tape. this stuff will not ever come out of your carpeting
the typical fiberglass install is 2 parts -- part 1 is making the boundary mould. this is where the fiberglass molds into the vehicles contours. use a few layers are you will not be able to add layers later without losing form.
part 2 involves the speaker mounts (speaker rings) and amprack mounts. you can build a wooden tray for an amplifier is desired. make sure to have room to run wires or run wires through pipes... for woofers, a wooden support frame is usually made for large projects. for smaller projects stiff metal mesh is used along with picture frame tape (metal strip with holes) to make a form for the inside. some users will opt to make this structure from MDF instead of fiberglass. for kick-panels a polyurethane foam is applied and carved to get a desired form. from there a layer of fleech is uses. t-shirts can be used. basically it is a layer that can add support for the extra 4-6 layers without folding.
my plan is to make the bottom and the back out of the fiberglass as that is where the most curves are. for the top ill just use MDF. Would it be groovy just using liquid nails to join the 2 pices to eachother? making it air tight of course...
ive been looking at this guide for a while now: http://web.njit.edu/~cas1383/proj/main/
ive been looking at this guide for a while now: http://web.njit.edu/~cas1383/proj/main/
It's relatively easy to make fibreglass acoustically dead. As mentioned, part of the "trick" is to make as little of the flat parts out of it as possible.
How I generally make my fibreglass enclosures is to build all the flat parts from MDF first, and assemble them, with the exception of the "face" plate, typically where the woofer will sit. No flat surface will be made up of fibreglass.
If you use standard automotive or marine resins, you can use multiple layers, but you cannot allow full curing time between them. Allow just enough time for the resin to not be tacky to the touch.
Tips: Buy lots of inexpensive paint brushes. Bristle brushes, not foam. The cheapest ones you can find will be fine, as you will not be able to re-use them. Buy lots, you'll end up using one for every batch of resin that you make. While you're at it, buy a box of disposable latex gloves.
If it's a hot day, make your batches small, or you'll be throwing out a lot of hardened resin in the shape of the disposable aluminum pie plate that you'll be using to mix the resin in.
Cut smallish strips of fibreglass matt (or cloth) before you start, because you won't have time to cut it once you've mixed the resin. I find that a size about 3" by 6" is about perfect (And fits into your disposable pie plate very nicely.)
Use lots of layers of aluminum foil and/or duct tape to protect the interior of your car and the backing area where you are going to be laying your fibreglass. If there's a hole in there that the resin gets into, you'll tear something apart trying to get your box out to fit the woofer. Cover an area that is larger than the intended area.
Overlap the fibreglass onto the ends of the MDF about 3" or more. This will make sure that they never separate. You can also "paint" the inside of the MDF with fibreglass resin. This will add strength to the MDF as well as seal it to make it airtight.
Cover anything and everything in the interior of the car that even remotely might get fibreglass resin dripped onto it.
If you will be working inside the vehicle with a polyester based resin (Which a vast majority of fibreglass resins are) then wear a respirator! I cannot stress this enough. It's bad enough what you're going to do to your hearing once you've installed a killer subwoofer, don't kill off the brain cells, too.
Enjoy!
How I generally make my fibreglass enclosures is to build all the flat parts from MDF first, and assemble them, with the exception of the "face" plate, typically where the woofer will sit. No flat surface will be made up of fibreglass.
If you use standard automotive or marine resins, you can use multiple layers, but you cannot allow full curing time between them. Allow just enough time for the resin to not be tacky to the touch.
Tips: Buy lots of inexpensive paint brushes. Bristle brushes, not foam. The cheapest ones you can find will be fine, as you will not be able to re-use them. Buy lots, you'll end up using one for every batch of resin that you make. While you're at it, buy a box of disposable latex gloves.
If it's a hot day, make your batches small, or you'll be throwing out a lot of hardened resin in the shape of the disposable aluminum pie plate that you'll be using to mix the resin in.
Cut smallish strips of fibreglass matt (or cloth) before you start, because you won't have time to cut it once you've mixed the resin. I find that a size about 3" by 6" is about perfect (And fits into your disposable pie plate very nicely.)
Use lots of layers of aluminum foil and/or duct tape to protect the interior of your car and the backing area where you are going to be laying your fibreglass. If there's a hole in there that the resin gets into, you'll tear something apart trying to get your box out to fit the woofer. Cover an area that is larger than the intended area.
Overlap the fibreglass onto the ends of the MDF about 3" or more. This will make sure that they never separate. You can also "paint" the inside of the MDF with fibreglass resin. This will add strength to the MDF as well as seal it to make it airtight.
Cover anything and everything in the interior of the car that even remotely might get fibreglass resin dripped onto it.
If you will be working inside the vehicle with a polyester based resin (Which a vast majority of fibreglass resins are) then wear a respirator! I cannot stress this enough. It's bad enough what you're going to do to your hearing once you've installed a killer subwoofer, don't kill off the brain cells, too.
Enjoy!
Body filler is not so good for *exposed*, large gaps. If it's in a place where the corner of whatever you are hauling in the truck could possibly zap it, you will have a gouge out of your nice new box. You can glass over the outside. If you use fiberglass cloth and not too much resin for the exterior layer it makes a texture that you may or may not like. You can always try liquid nails and silicon first, if you want and if you feel more comfortable with it... if it is good enough for you, then it is good enough, period.
Wear a mask when sanding body filler. Wear a mask and preferably goggles when you sand glass. You do not want to breathe little bits of glass.
If you can smell fresh resin through your respirator, exit and re-fit the respirator
Flat panels of glass can be made MUCH more rigid if you include a bit of skinny rope in between layers, with enough resin to soak it. It makes the flat, curvy. I built the flats on my box this way, and knocking on the side is like knocking on a solid chunk of wood. Dead.
I used clear packing tape to mask in my car. It didn't leave adhesive residue and didn't pull up much carpet. make sure it lays down smooth though or it will be one with the your box!
Wear a mask when sanding body filler. Wear a mask and preferably goggles when you sand glass. You do not want to breathe little bits of glass.
If you can smell fresh resin through your respirator, exit and re-fit the respirator
Flat panels of glass can be made MUCH more rigid if you include a bit of skinny rope in between layers, with enough resin to soak it. It makes the flat, curvy. I built the flats on my box this way, and knocking on the side is like knocking on a solid chunk of wood. Dead.
I used clear packing tape to mask in my car. It didn't leave adhesive residue and didn't pull up much carpet. make sure it lays down smooth though or it will be one with the your box!
a buddy of mine used cheap cloth to map out his mold on the bottom of his floorboard using the resin. then he used the mold outside the car to build the box. he said this way there is less exposure to fiberglass in getting all over you car. plus he said the cloth is easier to manipulate in tight areas. i believe he said he used a sweatshirt type cloth due to its thickness. it was his first time messing with fiber glass, but it sounded like a good idea.
good luck.
i might try it myself in the future.
good luck.
i might try it myself in the future.
If it were me I would make the bottom out of fibreglass as you intended and make the rest out od mdf, once it is all made just fibreglass the 2 halves together on the inside and presto, you have a molded box.
Once this has been done you could line the inside of the bottom with a damping material such as dynamat....
And as others have said be careful with the fibres as they aren't real good for you, wear gloves etc
Once this has been done you could line the inside of the bottom with a damping material such as dynamat....
And as others have said be careful with the fibres as they aren't real good for you, wear gloves etc
theChris said:
Can one use general purpose or finishing resins and sand the hardened surfaces between fiberglass layers?
Does fiberglass bond/react well with rigid foam (insulation)?
I either want build some home speakers using some rigid foam sandwiched between a few fiberglass layers on each side or I will have to construct some sort of honeycomb sandwich between the fiberglass layers, which will be harder. Which is a better idea?
It depends on if you use a polyester or epoxy resin.
Regular styrofoam and an epoxy resin is fine, and will make something lightweight and strong. Polyester resin will probably melt the styrofoam, but it does depend on the foam composition. I'd test it before doing a lot of building.
Oh, and whichever one will melt the styrofoam from heat if you mix in too much hardener.
Corrugated cardboard would be fairly safe as a medium, and come out reasonably rigid. The fibreglass itself will be fine if you make enough layers of it though, take up less time, and be easier to work with.
I made an MDF frame for my subwoofer enclosures, then moulded aluminum oven tray liners to be the outside of the enclosure. I laid the fibreglass in that, then when it was done, peeled the aluminium off, leaving me with a very nice fibreglass surface.
Regular styrofoam and an epoxy resin is fine, and will make something lightweight and strong. Polyester resin will probably melt the styrofoam, but it does depend on the foam composition. I'd test it before doing a lot of building.
Oh, and whichever one will melt the styrofoam from heat if you mix in too much hardener.
Corrugated cardboard would be fairly safe as a medium, and come out reasonably rigid. The fibreglass itself will be fine if you make enough layers of it though, take up less time, and be easier to work with.
I made an MDF frame for my subwoofer enclosures, then moulded aluminum oven tray liners to be the outside of the enclosure. I laid the fibreglass in that, then when it was done, peeled the aluminium off, leaving me with a very nice fibreglass surface.
Jimmy154 said:
Finishing resin (polyester) has a wax included that rises to the surface during cure. This would have to be stripped and then the polyester surface sanded for maximum adhesion. Sanding the waxed surface would grind some of the wax into the surface.
Laminating resin is best for polyester lay-ups, since it is made for making decent bonds between new and partially cured layers. Fully cured layers need to be sanded before additional layers are added, if you want maximum available strength.
Be warned that MEK, the common catalyst for curing polyester resin, can cause blindness if splashed into the eye. Take no chances.
Epoxy helps mediate some of the layup concerns, and can develop full bond strength between layers that aren't laminated at the same time. Existing layers in the 'green cure' stage will fully bond with additional layers. They are easily trimmed with a sharp razor knife at that time as well.
Be warned skin becomes sensitized to epoxy resin with exposure. At the point when tolerance is exhausted, it will cause an intense allergic reaction. Once this happens, exposure to even tiny amounts of epoxy can cause the reaction to reoccur. The amount of exposure required to cause this is unique to individual biology. It can happen the first time you mess with it, or the millionth time.
If you want to use epoxy, wear gloves and don't take my pitiful explanation as the only truth -read up on the warnings. If you can't find any info, email me and I'll find some links.
Lastly, for various honeycomb sandwiches, core materials, balsa laminates, and other neat stuff check out:
http://www.nida-core.com/
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