Whiterabbit's 2015 Mercedes GLA 45 AMG

[Whiterabbit]

Oh golly, I have always done things my way, and my IASCA scores for install showed it. A little creativity and practice yield lots of capability. I'm also lucky to have been around for the Maker Movement before it blew up and became this weird corporate burning man thing. When it was starting, it was just a collection of tinkers showing off their home projects on folding tables in a warehouse. Lots of free flowing ideas from amateurs.

This car is a shadow of wild ideas executed in the past. Last car had a 4x12 processor in the form of two DCX2496's converted to 12V operation. fed by a DEQ2496 with digital EQ, compression/expansion, 100 db/oct filters for feedback control (but were amazing notch filters), etc. I ran a Nakamichi CD player who's design was based on all the faceplate buttons being on a resistor ladder. So I installed no less than 15 buttons in my steering wheel and ran them through the same clockspring wire as the existing steering wheel controls and hacked the Nak unit so I could control 100% of the CD player (21 buttons or so) from the steering wheel. I could go on for days about the alarm.

This car I keep simple, mostly because it's an AMG TOO fancy in the aftermarket messes up the flow of the car. And at the end of the day, the flow of the car is what it's all about!

[Justin Zazzi]

But after three layers, it was so clear that this layup was SO RIDICULOUSLY OVERKILL I abandoned that. I made my box:

twill
x-mat
x-mat
coremat
x-mat
twill

And it will survive the nuclear holocaust. The strength is ridiculous, and because there is no wasted resin in the panel, it's light. I save the weight for the 2" thick MDF walls

So you made a composite ... composite? Very cool, I like how you chose the best material for each sub-job.

[Whiterabbit]

Ends up cheap too because its just a yard of each.

most important is zero post-layup sanding. Zero. Been there, done that, destroyed the t-shirt.

[Ge0]

Ends up cheap too because its just a yard of each.

most important is zero post-layup sanding. Zero. Been there, done that, destroyed the t-shirt.

So let's talk Resin. I'm thinking about glassing a sub box for my Porsche install. However, was also considering switching over to Epoxy resin vs. Polyester due to the reduction in dangerous out-gasing. Do you have an opinion one way or another?

Ge0

[Whiterabbit]

No opinion from me. Use what floats your boat. We aren't using these resins for their unique properties, and all are strong enough. We're not making surfboards that take a UV beating, or protecting fine woodworking and need a clear color, and 99% of us are not using the right glass-to-resin ratio for optimum strength, so we don't even need to consider strength since we're using the Russian principle of 'overbuild it' anyways.

I think the next box I glass might not even use fiberglass cloth, just a slurry of cheap resin, chopped fibers, and cab-o-sil. Then just paint it on. How bad could it turn out?

[Ge0]

No opinion from me. Use what floats your boat. We aren't using these resins for their unique properties, and all are strong enough. We're not making surfboards that take a UV beating, or protecting fine woodworking and need a clear color, and 99% of us are not using the right glass-to-resin ratio for optimum strength, so we don't even need to consider strength since we're using the Russian principle of 'overbuild it' anyways.

I think the next box I glass might not even use fiberglass cloth, just a slurry of cheap resin, chopped fibers, and cab-o-sil. Then just paint it on. How bad could it turn out?

I won't have a lot of space to build up numerous layers. So, the layers that I do lay down must be solid. I watched a few of the TAP Plastics tutorial videos. Between that and your write-up I think I have an idea. Iit will be a tight squeeze but I think I can make it work. Worse case, I go back to my baffle.

Ge0

[Whiterabbit]

Easy. You can get away with < 1/4" I am sure. 1/4 is overkill when you do it right.

Use standard woven fabric, and try to get the 70%/30% glass-to-resin ratio for max strength. You don't have to weigh anything, just squeegee it untill you barely (but completely) wet the cloth. That will give you maximum strength with no waste. if you see resin pooling anywhere, it's wasted material, doesn't help strength, and just weighs you down. 70/30 is essentially glass fibers close-packed with resin in between and no

If you do it this way, you have to do the whole layup in one shot or you're done, so you have to make sure your glass is all cut and ready for layup. Not sure how many layers will do it, my guess is 5-7 depending on what thickness fabric you choose. You'll want a middleweight so you can layerup for your thin overall thickness. Maybe 6 or 8 ounce?

The resins I like for this are the kind without a wax for surface cure, and SLOW cure with long pot time, to ease your layups. I prefer not to add thinners, that's just an opinion. I still don't worry about epoxy vs polyester. If you want it to be maximum pretty, you pick medium cure epoxy or surfboard resin. Both cure clear, unlike the resin I picked which cures baby-shit brown.

[mumbles]

Nice work, I applaud your skills!

For your next all-out older car, do you have a vehicle in mind? I've always been fascinated by the thought gutting a vehicle to use solely as a car audio platform.

[Whiterabbit]

I've been dreaming or a rear or mid-engine car. VW bug up to Porche-anything. Karmann Ghia. I think it would be so neat to put the subwoofer under the hood in a really fancy 6th order band-pass box, with the port "ported" into the cabin. Ditto for midbass placement, utilizing space far, far forward, with unlimited space for backwave management.

It'll never happen. But a guy can let his imagination fly high.

[Jscoyne2]

Ends up cheap too because its just a yard of each.

most important is zero post-layup sanding. Zero. Been there, done that, destroyed the t-shirt.

I am curious about actual price comparison. I did the math..well maybe...im actually trash at math but if im right. The Knytex is .75oz for around $0.68 a square foot. I can get 1.5oz chopped strand from a local boat repair shop for around $0.72 per square foot. So basically the same price but my local stuff is twice as thick...and your way is actually more expensive per SqFt when you start factoring in excessive shipping cost.

For something like a 100% FG sub enclosure where you need 5-8 layers of chopped mat to get the desired 1/4" thickness, do you think that Knytex/coremat/twill would end up being cheaper even with the Knytex being half as thick as mat? Would total resin consumption of knytex/coremat vs mat offset the costs towards your way?