Help me build a simple speaker box. - Finished!

Edit: Photos of the finished product here!

So, I ride my bicycle. A lot. I also enjoy my music. A couple years ago I decided to build myself a stereo for my bicycle.

I've now gone through 3 different iterations of the stereo, changing it for the better each time, but there is still one issue with it that I want to solve. Here's the current version of the stereo, built into a trunk bag:

IMAGE(http://i135.photobucket.com/albums/q133/serengeti000/null_zps3a9a5161.jpg)

This version has 2 main flaws. 1. The bag is fabric and flexible, so it's not as "punchy" as a rigid box would be. 2. The equipment inside weighs about 11 lbs, which isn't a lot, but over time it means the bag takes a beating. Too many bumps and bangs and you end up with the seams coming apart:

IMAGE(http://i135.photobucket.com/albums/q133/serengeti000/null_zps3c3632c5.jpg)

I'm currently on my 3rd bag. They only cost $20, so it's not a huge deal, but it's a major hassle cutting them and cramming all the gear inside. As such, I've decided to (hopefully) solve both issues by building a fiberglass box for the stereo.

One problem, I've never worked with fiberglass before.

My current thought is that I'll put together a simple wooden box of the appropriate dimensions and then just cover it with 3 or 4 layers of fiberglass. Once it's all cured and painted, I'll use my dremel to cut out the speaker holes and other bits and call it good.

I've ordered some biaxial fabric and some vinyl ester resin for the fiberglass and I'm thinking that with the strength of the fiberglass, I can just use the lightest wood I can find for the initial box, as it will be acting primarily as a mold, except that I won't be removing it afterwards. I don't see this being very complicated, and I'm pretty handy, so I expect it will all go pretty smoothly, but if anyone has worked with fiberglass before and has any tips on the process, I'd be glad for any input.

I also intend to take a bunch of pics and notes along the way so that I can put together a bit of a how-to doc for some of my friends, and I'll be sure to post those here too.

Some of the things I'm not 100% certain about:

- What type of wood should I use for the inner box. 1/4" MDF? It's kinda flexible, but that won't be a problem once it's covered in fiberglass, right?
- How many layers of fiberglass? I'm thinking 3 or 4 would be plenty with the fabric I've ordered.
- Fiberglass eventually breaks down in sunlight, so I'll want to paint it. What type of paint do I use?
- Do I need to add cross-beams inside to reinforce the fiberglass where the speakers are mounted? Couldn't hurt to add a little more strength, I suppose.
- It needs to be waterproof. I assume the fiberglass will take care of that nicely, and the speakers are waterproof already, so I think I'm good.

Does it have to be a stereo?

Is space an issue?

Now that is out of the way.

I am wondering what your experience is in working with fiber glass. It is not the easiest thing to work with molding and shaping.

No experience whatsoever. It'll be an adventure

Build a good form first and make sure it is precisely the interior shape you want.

Covering wood with resin and cloth will make it heavy.

Can I ask why you're looking at this approach?

Molding it would let you use just the cured fibreglass, but it's much harder.

There are UV resistant resins.

Have lots of acetone on hand for cleanup.

Check out some boat building forums.

Depending on the thickness and weave of the cloth you're using, 3 layers will be overkill. If you're glassing a box, you're basically waterproofing it, right?

If you mix it really hot, it can flash on you. THAT is an adrenaline rush.

I did want to also add. You might be able to get away with using a leather Motorcycle tail bag or saddle bag.

IMAGE(http://www.vikingbags.com/images_products/viking-cruise-sissy-bar-bag-1275lar.jpg)

Ghostship wrote:

Covering wood with resin and cloth will make it heavy.

Can I ask why you're looking at this approach?

Molding it would let you use just the cured fibreglass, but it's much harder.

Primarily because I'd like it to be a single, solid box. No lid or openings other than the holes for the speakers and switches. I'm not really sure how I'd go about doing that with a mold. Maybe build some kind of internal mold that can be broken down into pieces once the fiberglass has hardened and then removed piece by piece via the speaker holes, but that seems pretty complicated. That's why I was leaning towards just building a box out of the lightest wood I could find and leaving it inside.

Ghostship wrote:

Depending on the thickness and weave of the cloth you're using, 3 layers will be overkill. If you're glassing a box, you're basically waterproofing it, right?

Waterproofing and strengthening. It's going to take a lot of abuse.

[quote=Serengeti]

Primarily because I'd like it to be a single, solid box. No lid or openings other than the holes for the speakers and switches. I'm not really sure how I'd go about doing that with a mold. quote]

Styrofoam and plastic wrap.

What about prefab hardshell panniers like BikeBins?

edit: Oh, no lid. I'd think access to the electronics would be a good thing though. Or is this mostly a cosmetic issue? I believe fiberglass is generally laid on a form. Making a closed cube seems like it would be pretty difficult. I imagine what you'd do is make two halves and them join them afterwards with a fiberglass patch of sorts.

Looked at the bike bins before. They would work, except I'd be giving up a lot of cargo space. The goal is to keep the stereo as a rack top unit so I can still use front and rear panniers. Here's what the current stereo looks like, though I didn't have my front rack on for this pic:

IMAGE(http://i135.photobucket.com/albums/q133/serengeti000/IMG_2017.jpg)

The electronics would be accessible by removing a speaker. There would generally be no reason to get inside unless there was a problem.

Paleocon wrote:

Styrofoam and plastic wrap.

Ooh, then just carve it out afterward. That could work!

What about a hard insert inside the cloth bag?

Glassing a box would be much easier than making a mold.

I think you'll be fine with one layer of a fine cloth. There's a gauge of cloth for decking wood boats that vanishes when it's wet down with resin. Having refinished a 10ft hydroplane, I used 1/4" plywood, with one layer of cloth, and strip reinforcing at the seams. I used West System epoxy, instead of polyester resin, but same thing structurally. I think a speaker would be OK with a thin wood veneer, and one layer of a decking cloth.

If you did want to consider it:
There's a prop builder who has a video on making a helmet. you put the resin in a mold and tumble it until it's cured. Might be a good one piece box method. Making the initial mold would be easy, since it's just a box. You would probably tumble a finish coat or two, then go inside and use a chopped strand mat for strength. The access hole would be the speaker cut out. Make it small for the tumble, cut it larger to reinfoce the inside after.

for pure entertainment value

Making a parting mould is pretty straight forward.

Serengeti wrote:

Looked at the bike bins before. They would work, except I'd be giving up a lot of cargo space. The goal is to keep the stereo as a rack top unit so I can still use front and rear panniers. Here's what the current stereo looks like, though I didn't have my front rack on for this pic:

IMAGE(http://i135.photobucket.com/albums/q133/serengeti000/IMG_2017.jpg)

The electronics would be accessible by removing a speaker. There would generally be no reason to get inside unless there was a problem.

Paleocon wrote:

Styrofoam and plastic wrap.

Ooh, then just carve it out afterward. That could work!

It would be easier to melt/cut the styrofoam into pieces using a hot knife through the speaker hole. Make sure your form is hollow so that it is easier to dismantle once the glass hardens.

Yes. I have done this before.

I urge you to stop while you are ahead!

You are going to find yourself sliding down at break neck speed, that slippery slope of "just one more upgrade."

IMAGE(http://www.geekologie.com/2008/08/18/bike-system-4.jpg)

What about thin gauge stainless steel? Won't be too heavy and you can make a lid that is lockable, add a grate over the speaker for it's protection, and add hooks and loops near the bottom edge to fasten the panniers to.

FSeven wrote:

What about thin gauge stainless steel? Won't be too heavy and you can make a lid that is lockable, add a grate over the speaker for it's protection, and add hooks and loops near the bottom edge to fasten the panniers to.

Thought about that, but I feel like without any welding skills or equipment it would be difficult to make that waterproof.

Serengeti wrote:
FSeven wrote:

What about thin gauge stainless steel? Won't be too heavy and you can make a lid that is lockable, add a grate over the speaker for it's protection, and add hooks and loops near the bottom edge to fasten the panniers to.

Thought about that, but I feel like without any welding skills or equipment it would be difficult to make that waterproof.

Well it's your lucky day! I happen to run a metal shop. Give me some dimensions on a box and what size the cutout needs to be for the speaker. Even better, if you can find a schematic of the speaker online with speaker size and the distances between mounting holes, I can make a box for you. I'd only charge you the cost of the material ($0.50 per pound so it would probably be under $5.00 in material) and then whatever the cost would be to ship to you. I can also procure some gasket material to put on the lid and around the speaker hole. All seams would be welded. It would basically be a waterproof/indestructible/lockable box.

And in the event I made it and you decided you didn't want it, I'd keep it for myself.

Give it some thought.

FSeven wrote:
Serengeti wrote:
FSeven wrote:

What about thin gauge stainless steel? Won't be too heavy and you can make a lid that is lockable, add a grate over the speaker for it's protection, and add hooks and loops near the bottom edge to fasten the panniers to.

Thought about that, but I feel like without any welding skills or equipment it would be difficult to make that waterproof.

Well it's your lucky day! I happen to run a metal shop. Give me some dimensions on a box and what size the cutout needs to be for the speaker. Even better, if you can find a schematic of the speaker online with speaker size and the distances between mounting holes, I can make a box for you. I'd only charge you the cost of the material ($0.50 per pound so it would probably be under $5.00 in material) and then whatever the cost would be to ship to you. I can also procure some gasket material to put on the lid and around the speaker hole. All seams would be welded. It would basically be a waterproof/indestructible/lockable box.

And in the event I made it and you decided you didn't want it, I'd keep it for myself.

Give it some thought.

I will have to keep that in mind for my numerous projects.

Why not just a wooden box? Wood is a great speaker material, you can work it pretty easily with only a few tools, and it can be made waterproof. You can use inexpensive wood like poplar and paint it or you could use some nice teak (which is already pretty waterproof) that would look great.

If you do a metal box would it affect the sound? Could you line it if so?

Another thing to think about is that the cloth bag affords the components some cushion over rough terrain. Would you need to cushion the components with a solid (wood, metal, fiberglass) box?

FSeven wrote:
Serengeti wrote:
FSeven wrote:

What about thin gauge stainless steel? Won't be too heavy and you can make a lid that is lockable, add a grate over the speaker for it's protection, and add hooks and loops near the bottom edge to fasten the panniers to.

Thought about that, but I feel like without any welding skills or equipment it would be difficult to make that waterproof.

Well it's your lucky day! I happen to run a metal shop. Give me some dimensions on a box and what size the cutout needs to be for the speaker. Even better, if you can find a schematic of the speaker online with speaker size and the distances between mounting holes, I can make a box for you. I'd only charge you the cost of the material ($0.50 per pound so it would probably be under $5.00 in material) and then whatever the cost would be to ship to you. I can also procure some gasket material to put on the lid and around the speaker hole. All seams would be welded. It would basically be a waterproof/indestructible/lockable box.

And in the event I made it and you decided you didn't want it, I'd keep it for myself.

Give it some thought.

Well holy crap, that would be awesome! I'll whip up a drawing and get back to you.

Ok, here's the speaker diagram:

IMAGE(http://i135.photobucket.com/albums/q133/serengeti000/speakers_zps6c3db718.png)

As for the box, I'm thinking 7" wide, 12" long, 8" or 9" high (the speakers are 7 3/16" tall, so might have to go taller if there's going to be a lid) with the speakers on the 8x12 sides. That would be roughly the same dimensions as my current bag, which I can fit on the rack without blocking the panniers.

On the inside I was going to build a little cubby to hold the battery securely at one end of the box, the cubby would need to be 4 1/2" wide (internal), 2 3/8" long (internal) and 4" tall. I'd leave the top of the cubby open for wiring and I figured I'd just use some velcro tape in the bottom to prevent the battery from bouncing. Here's a top-down view of what I'm talking about:

IMAGE(http://i135.photobucket.com/albums/q133/serengeti000/214da648-23d9-46c7-925e-b55abb8321a7_zps8799e75c.jpg)

The speaker lines in that diagram are from direct measurement, so the battery box won't interfere with the speakers.

What do you think, doable?

I know it's not really what you were asking, but after reading what you're trying to do I couldn't help but think about how I'd go about it.

Build a frame out of wood or perhaps even better use perforated angle steel which can be bolted together much like an Erector Set and then cover it with molded Kydex panels. Kydex is cheap, durable as hell, and waterproof. Better yet Kydex won't crack or shatter if you drop, and it would be a heck of a lot lighter.

You wouldn't get the rigidity of fiberglass, but it would be a lot better than cloth, and I doubt the bass response would suffer all that badly.

This is definitely doable.

I noticed you had a small panel on the front which has what looks like a power switch and a headphone jack.

Do you need some sort of rectangular cutout to mount that panel?

Given that you seem to update/change your electronics and speakers occassionally, would you want the speaker cutouts/mounting holes to be on panels that are separate from the main box and then just bolt those panels onto the box? That way, when you change gear you just need new panels and don't have to mess with the overall container.

FSeven wrote:

This is definitely doable.

I noticed you had a small panel on the front which has what looks like a power switch and a headphone jack.

Do you need some sort of rectangular cutout to mount that panel?

Nah, the reason that panel was there was for rigidity for the switch and audio input. If the box is metal, I wouldn't need that panel at all. I can drill out the holes for the switch/audio myself.

Lent wrote:

Given that you seem to update/change your electronics and speakers occassionally, would you want the speaker cutouts/mounting holes to be on panels that are separate from the main box and then just bolt those panels onto the box? That way, when you change gear you just need new panels and don't have to mess with the overall container.

I think I'm at the point now where I'm satisfied with the components, so I don't intend to swap anything out going forward. Well, I may switch up the amp maybe, but the speakers I have now are awesome, so permanent mounts are fine.

Should have a Solidworks model for you this afternoon. I'll post up pics and you can tweak it however you want. I'm currently trying to decide on a lid design. Not sure if I should go with hinges (susceptible to leaking) or a slip on lid with two lockable clamps on the non-speaker sides.

Sweet. I don't tend to let rain stop me when I'm riding, so leakproof would be ideal, though really all the components except the amp can take a bit of moisture without issue.

FSeven wrote:

Should have a Solidworks model for you this afternoon. I'll post up pics and you can tweak it however you want. I'm currently trying to decide on a lid design. Not sure if I should go with hinges (susceptible to leaking) or a slip on lid with two lockable clamps on the non-speaker sides.

I say put an ammo box clamp and rubber o ring on it just for the cool factor.

Paleocon wrote:
FSeven wrote:

Should have a Solidworks model for you this afternoon. I'll post up pics and you can tweak it however you want. I'm currently trying to decide on a lid design. Not sure if I should go with hinges (susceptible to leaking) or a slip on lid with two lockable clamps on the non-speaker sides.

I say put an ammo box clamp and rubber o ring on it just for the cool factor.

That's not far from what I had in mind.

Here's a rough model. There will obviously be speaker cutouts on both sides.

IMAGE(http://i.imgur.com/mtrjfxl.png)

I made the flanges turn in on top because as Paleocon alluded to, there will be a rubber gasket on there which will allow the box to be sealed up nice and tight. All seams will be welded. Water will not get inside this thing.

IMAGE(http://i.imgur.com/8ZTr68e.png)

I would make it a piano hinge and a ammo box clamp.

Looks awesome!

IMAGE(http://images.lazygamer.net/2012/10/shut-up-and-take-my-money.jpg)

Picture with the compressing clamp.

IMAGE(http://i.imgur.com/SkaMUJl.png)