intermediate installation information

[DRCinc]

Intermediate installation

• Ohms law
  
• Basic custom fab
  
• Box building
  
• 
  

• Ohms law:
  

Ohms law applies to anything with a circuit.

Ive found a very good refrence website that can help you out a lot.

http://openbookproject.net/electricCircuits/DC/DC_2.html

This site basically shows you the basics of OHMs law. How to find resistance(or impedance/ohms )

It also explains how to find voltage and how to find amp’s so it can come in handy when going over your electrical system. It also comes in major handy when wiring anything having to do with speakers. Just in case those of you who don’t have a DMM need to find out exactly what you are wired at or if your stock electrical can handle what you want to put in your car.

http://www.hamuniverse.com/ohmchart.gif

For those of you not willing to read ill give a basic breakdown.

The picture above displays a triangle with amps, current, and resistance

If you need to find any of those three you do a simple math equation

• V=volts
  
• I=amps
  
• R=ohm’s
  

• Volts = amps x ohm’s or V=IxR
  
• Ohms = V/I or volts divided by amps
  
• Amps=volts divided by OHMS or V/R
  

Basic custom fab

Custom fabrication has a lot of aspects to consider. In this case I will be going over the basics (I.e. A pillars, door panels, and subwoofer boxes)

Most of the time you either have a space designated for you to work with either you will have a body panel to work off of or you will have a spot to fill.

Body panels- most times for a basic build you will have a body panel to work off of.

Ill do it by steps, step one(pre fab work) if it is ABS plastic your working with you’ll want to scuff it to make anything you have to apply later stick better a light pass over with some sand paper will suffice you don’t have to gash holes in it because in the end you’ll be creating more work for yourself than you want.. Also if you sand ABS too much you’ll get little flakes in it that could possibly stick up through the bondo and other things. This rule applies even if you are going to be we-wrapping the piece which ill go over a little later in the reading.

After your ABS is nice and scuffed your going to want to rub it down with acetone. This is to get an little particles that could prevent anything sticking to it later on. Its all about making sure your preparation is as thorough as possible that way you wont have to do double work.

Assess the area your going to want to work with and if you are doing multiple panels the same way you are going to want to work on them at the same time that way they don’t look too lopsided the idea is to make it look as factory as possible without fucking anything up. Make sure you have access to a decent amount of tools because you are going to need wooden framing(skeleton) I have used the ABS skeleton rods and they are not that good. Even low temp plastic can be very aggressively temper mental if not used correctly. No matter what you do having a wood background always helps in the long run.

Jigsaw. Great tool for eliminating excess wood from a large portion of a specific area

( cutting from full sheets can give you the smaller pieces you will need to work with for other tools)

Table saw- you will need this if you need absolutely straight cuts, they can also do a number of other things/9i.e. 45’s and specific angles if used properly)

Router- probably one of the most underrated tools in a audio installers arsenal. With a router you can easily multiply the number of specific shapes you have made out of wood. This eliminates you having to cut 2 or 3 pieces by hand and have someone thing slightly different. It will also help with making perfect circles

Drill- almost any drill will work. I like to use a dewalt 12v impact drill personally but if you’ve got to it will work. you’ll need to drill pilot holes in the ring for mounting the speaker and you will most often have to drill holes in the plastic itself to give the body filler something to grab a hold of once you start getting to the dirty parts

First off you are going to have to create something for your speakers to mount to. I am going to use speaker install as an example for this talk because it is the most basic you can get as far as customization. You first have to make the MDF rings for your speakers. Mobile solutions makes a ring set that works wonders and you can put it right on the router and have perfect circles.

You also have an option to flush mount the speaker. For that I find that its better to use ¾” for the bottom half and make a ring that fits right around the outside diamitar out of ¼” MDF, once you have both line them up against one another and glue/ staple them together . Test fit it with the speaker to make sure everything fit’s the way its supposed to .

Once you have that done you are going to have to suspend the trim rings over the plastic piece so that once you get some fleece on it you can see the shape of the fiberglass.

http://s1104.photobucket.com/albums/h336/DRCinc/?action=view&current=27bfa7ac.jpg

These are the trim rings I made for my set of door panels

This is a good example of suspending the trim rings so you can get the shape you want. It helps to have a history with wrapping boxes and such once you get into the stretching portion of the fleece

http://s1104.photobucket.com/albums/h336/DRCinc/?action=view&current=0011b3ec.jpg

People like to use popsicle sticks some people use scrap pieces of MDF and some use the ABS plastic rods. Its just a matter of personal preference at that point.

Stretch your fleece. Get it as tight as you can so that the shape takes over and you can already see exactly what your finished product will look like

http://s1104.photobucket.com/albums/h336/DRCinc/?action=view&current=fbc57070.jpg

Use CA glue or any type of adhesive you can to get the edges to wrap around the back to secure the back portion of the fleece. Staples will also work depending on the application of course

Next you’ll have to start mixing your resin. You can easily look up a chart for catalyst to resin measurements.

Its fairly simple you can buy a gallon of the 3M resin with catalyst at home depot for about $50. I like using that stuff, mixes easily and goes on pretty well.

if you are using fleece that is thick enough you wont really need the fiberglass matte. I have had A LOT of people tell me that this simply wont do because you need the matte. Realistically you do not need it provided your fleece is thick enough and you use enough resin you will have all the structure you need, it will take A LOT more than a swift kick while hopping in your car to break this stuff.

Lay down a nice coat of resin so that you have something for the matte to stick to, after that layer is done start laying on the matte. You want to use smaller pieces and keep everything as uniform as possible, once you have a nice layer of matte on the piece( all of it don’t cheap out) you want to pat it down with some more resin, this will take the color out of the matte so it will no longer appear white it will be more of a hazy glossed clear. Repeat with more matte until you have achieved the structural integrity you want.

Let dry overnight

Once everything is dry you are going to want to get some body filler. Ive found that bondo works just fine your only going to use it to smooth things out so when you paint/wrap the piece it doesn’t look all funky.

Once you are happy with the general shape and coverage of the Bondo you are going to want to take a couple more steps to make sure your piece is fully prepared for paint or fabric.

That being said there are 2 basic options for you project once all is said and done. You will want to lay down a thick coat of pulpier(its what I use and it works wonders), you are going to want to see ripples in the primer. that’s okay! Do not freak out. The idea is to fill all the little pinholes in the bondo and fill in the little scrape lines from the sand paper as well. Once your poly is dry you want to just throw some black over it so that you can see exactly where you need to sand. Fiberglassing is not quick but its fairly easy to get the overall idea. It is far more difficult to make right. That being said get to sanding!

Once you are happy with how it came out you are going to want to primer it again. If you can still see dips in it you wanna add more and keep sanding. don’t forget to start at the more abrasive sandpaper and continue up into the finer stuff. That way you wont have any serious scuff marks in your finished product.

If you are going to be wrapping the piece with a fabric you wont have to make everything absolutely perfect. If you are going to be painting the piece everything HAS TO BE FLAWLESS! Any imperfections in the bodyworks/glasswork will be brutally showed in the finished product every single bubble, dip, and imperfection will be amplified and show up.

Box building

I wont be going over box design in this section just because it takes a lot more than most people think to design a box. That being said ill go over basic box building.

Most times you are going to use ¾” MDF for basic car audio applications some people like to use birch wood but I personally have never tried it so I cannot say whether it is better or worse.

First of all you are going to need to assess the amount of space you are willing to lose for the box(I.E. wall, most of the trunk, all of the trunk etc etc)

After that is done you are going to want to take measurements and get a box design. If you don’t already know how to do so you are going to want to find someone who is willing to do it for you. In most cases a box design with a cut sheet will be around $10-$20 depending on the person.

After you know exactly what you are going to be doing you are going to want to cut the wood up. Easily done with a table saw and more skillfully with a jigsaw. Map everything out on the full sheet and cut accordingly. After you have gotten everything cut you are going to do what I call a dry mock this just means putting everything together without glue or nails. Just to make exactly sure how everything will work. Most times I try to do this within the portion of the car that the box will be in. just to make sure you clear all rods or anything like that. Once that is done you can start with the box build. I start with the bottom portion and the sides, I find that you can use a nail gun or countersink screws, there is a number of different ways to do it my preference is to lay glue down on the two intersecting joints and shoot nails into it once you have them properly lined up. Clamps also help a great deal with this because they can act as a second set of hands if need be. Most times ill get a friend or coworker to help me with this step just because its almost impossible to hold 2 pieces of wood tightly together and shoot nails into it simultaneously. Get the sides done and attached to the bottom, then if you are going to be doing 45’s you are going to want to add those as well because it will be significantly harder to get those in the box once the top is on. I would say save the portion the sub will mount to for last just because it is the easiest way to do it. If that means completing the box without a face do so. If it means no top even better. Without the hole cutout it will make applying resin fiberglass or bondo a lot easier. Do any sealing out you need to do while the box is still slightly apart even if its just a little bead of wood glue along all the edges. I NEVER recommend letting a box leak. It is not excusable. You are already there. Take the time to do it right or you will be doing it again

[DRCinc]

i kept this somewhat short. just like the last one if someone feels something specific needs to be added

[c.director]

Good read.