Originally Posted by truracer1000
door panels have the same basic prcedure...the reason the door panel you pictured above is cracked is not only because it isnt think enough to withstand the pressures of being opened and closed everyday, but this guy obviously didnt check to make sure the door panel cleared the dash when the door is closed. their are a buch of little thing that you have to think about before getting started...im not trying to say i know everything if thats what anyone is getting out of this im just saying that you have to think ahead and plan..all of these things can be prevented!!!
Yea this guy knows what he is talking about. I just have some things to add. First to simplify the process I recomend making the box in 2 sections (I have done this only for a box that the bottom isn't seen, even though im sure there is a way to do it for doorpanels... i just havent tried yet.) First just use a scrap piece of plywood for the base and completely cover it in masking tape. The blue painters tape works perfectly. Make sure to criss cross the layers to make sure no resin soaks through. Then if you want add a layer of aluminum foil and cover that in the same process with the tape. You will see why I do this in a second. Next cut a "ring" (the middle is cut out leaving the edge about 1 inch think) the shape of the bottom of your box. Cut your speaker rings that the subwoofer will be mounted to. Use 3/4 inch MDF. The speakers usually come with a template. If not the users manual will state the diameter of the hole. Also at this time you can cut a seperate ring to the outer diameter (only if you want the beveled look) Mount the ring(s) onto the pegs at the desired hieght and angle. At this time you should also build the rest of the framing now Make sure to construct a port if you want one. Remember ported enclosures always play about 3db louder. Use screws when attaching to the plywood, remember you willl not be using this piece. Then use a good strong glue to hold down the fleece, I prefer 3M, and stretch the 100% polyester fleece starting at the ring and working down getting the desired shape. Countinue wroking the flece all the way down past the base MDF ring and onto the taped up plywood. This is to insure uniform thickness. you will trim off this extra later. Now it is time to apply your resin. Use a paintbrush trimmed short. This helps with applying the resin. Use a dabbing/stabbing motion. This helps eliminate air bubbles which as we all know results in cracks. After doing this allow the resin to cure and then aplly a second coat, also using the stabbing motion. Now apply the first layer of mat to the outside of the box in 1/4 inch strips. Make sure to continue onto the plywood just like with your resin and fleece. This just makes it easier to work with. After letting that cure it is time to remove the temporary scrap plywood. Remove the screws and pull off the plywood. It should pop right off if you did your tape right. Use some sandpaper to remove any tape from the mdf ring and trim away the extra. Now for the reason why the box is in 2 parts. You can now flip your box upside down and apply fiberglass to the inside of your box. This makes it a lot less time consuming and a lot less messy. A good inch and a half of air bubble free matting will be good for any 1000 watt subwoofer. Add more matting if the power is higher. Now after letting that cure for a couple hours cut out the fleece and stray fiberglass/resin form the speaker hole and port (if you have one). Now for the bottom of the box just trace the base onto some 3/4 inch MDF and cut it out. Stack the box onto this cutout with glue inbetween. When the clue has cured cover the seam with silicone. The result will be an air tight box. Unless you have a port that is. If you would like you can use some spray adheasive and some polyfil stuffing to cover the inside edges of the box. This will stop and resonance or echo inside the box that decreases sound quality. Now just use kitty hair filler and regular body filler in that order to smooth out the exterior and then paint or cover your box. Drill a hole for the speaker wire and then seal it up around the hole and your done. After you install the sub of course.